Foto personale

Pagina personale di Alessandro GUALTIERI

Dipartimento di Scienze Chimiche e Geologiche
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

A. Gualtieri, M. Boccaletti, I. Zanatto ( ) - Concrete mixture comprising thermally inactivated cement- asbestos [Brevetto (285) - Brevetto]
Abstract

This invention regards the transformation of cement-asbetsos at 1200 °C to produce a secondary raw material to be recycled as pozzolanic material in the production of concrete

A. GUALTIERI ( ) - Formulazione di un impasto ceramico da gres porcellanato cotto a bassa temperatura [Brevetto (285) - Brevetto]
Abstract

L’invenzione riguarda la formulazione di un impasto innovativo per la produzione di piastrelle ceramiche, con le caratteristiche del grès porcellanato ma cotto a bassa temperatura, ed il relativo processo di cottura industriale. La temperatura massima di cottura di questo impasto innovativo è di 950 °C ed il ciclo di cottura ha una durata complessiva non superiore a 60 min. L’invenzione nasce dalla considerazione che la serie di reazioni chimiche (trasformazioni mineralogiche) e fisiche (sinterizzazione, greificazione, ecc) che portano alla formazione di una piastrella di grès porcellanato, può essere riprodotta partendo da una miscela di materie diverse, in un intervallo di temperatura più basso rispetto a quello utilizzato per la produzione di grès porcellanato (circa 1200 °C). La temperatura massima di cottura di questo impasto innovativo è circa 250 °C più bassa rispetto a quella normalmente utilizzata nei cicli industriali. Il ciclo di cottura è realizzabile in un comune forno a rulli da piastrelle che utilizza la tecnologia esistente. Per far avvenire reazioni di greificazione a queste basse temperature è necessario utilizzare un fondente sintetico, cioè una fritta basso-fondente che promuova, in sinergia con altre fasi, la greificazione. Il prodotto, con caratteristiche molto vicine a quello del grès porcellanato extra-white, risulta estremamente competitivo e si colloca in una fascia di costo più vicina a quello della tipologia super-white. I vantaggi di questa nuova tecnologia produttiva sono: (i) la cottura a 900 °C che permette di ottenere gamme di colori in massa diverse da quelle che si ottengono per il grès porcellanato; (ii) un risparmio dal punto di vista energetico; (iii) un risparmio su altre voci relative al processo di cottura nel forno a 900 °C quali: riduzione drastica dell’usura del forno, riduzione drastica dell’usura dei rulli, utilizzo di rulli più economici; (iiii) aumento della produttività. La produttività di questa miscela ceramica è più alta rispetto a quella di un grès porcellanato poiché il ritiro medio si attesta sul 4% rispetto al valore medio di mercato del grès porcellanato di circa 7-8%.

A. Gualtieri, M. Boccaletti e I. Zanatto ( ) - miscela di calcestruzzo comprendente cemento-amianto inertizzato termicamente [Brevetto (285) - Brevetto]
Abstract

Invenzione che descriver la trasformazione termica del cemento-amianto a 1200 °C per la realizzazione di una materia prima secondaria da utilizzare come legante nelle miscele per la produzione di calcestruzzo.

A. GUALTIERI ( ) - Processo per la trasformazione termica di lastre di cemento- amianto utilizzando un forno continuo [Brevetto (285) - Brevetto]
Abstract

Processo di lavorazione industriale per la trasformazione termica diretta di pacchi sigillati in materiale plastico, contenenti lastre di cemento-amianto derivanti da normali operazioni di rimozione e che, in alternativa, verrebbero conferiti in discarica controllata. Il processo di trasformazione termica diretta dell’intera confezione di lastre avviene utilizzando un forno industriale continuo “a tunnel”, generalmente usato per la produzione di laterizio, di lunghezza non inferiore a 50 m. Il ciclo di cottura per ottenere la completa trasformazione delle fasi dell’amianto (sia amianto di serpentino che amianto di anfibolo) in fasi silicatiche di calcio, alluminio, magnesio e ferro, innocue per la salute dell’uomo e degli animali, prevede una rampa di riscaldamento da temperatura ambiente ad una temperatura compresa fra 1200 e 1300 °C in non meno di 12 ore, una permanenza in condizioni isotermiche alla temperatura raggiunta nello step precedente non inferiore a 20 ore in modo da ottenere una temperatura al cuore del pacco di non meno di 1000 °C per 20 ore. Infine, un raffreddamento non forzato in un tempo non inferiore a 18 ore. Il forno industriale deve assicurare il completo isolamento del materiale in cottura dall’ambiente esterno e deve essere dotato di un sistema di post-combustione, con una temperatura interna non inferiore a 1200 °C, attraverso il quale devono passare tutti i fumi derivanti dai processi di trasformazione della confezione di lastre (combustione della confezione medesima, processi di disidratazione, decarbonatazione, deossidrilazione).Questo processo di lavorazione industriale è altamente innovativo perché non prevede intervento meccanico prima della cottura come la macinazione del materiale contenente amianto, operazione pericolosa che può comportare la dispersione di fibre di amianto nell’ambiente.Il forno verrà alimentato a metano al fine di contenere le emissioni in atmosfera di gas di combustione. Lo stesso impianto potrà essere utilizzato per la trasformazione termica dell’amianto friabile, di manufatti di vario tipo contenenti amianto e di amianto inglobato in materiale plastico. Dopo il trattamento, in perfetto accordo con le tecniche di trasformazione cristallochimica (modificazione chimica e ceramizzazione) descritte nella Tabella B del Decreto Ministero dell’Ambiente 29 luglio 2004, nr. 248, l’amianto è trasformato in un materiale a matrice silicatica, non fibroso, innocuo che sarà macinato a secco, omogeneizzato ed eventualmente riutilizzato come materia prima per svariate applicazioni industriali.

A. GUALTIERI; ZANATTO I ( ) - Processo per la trasformazione termica di lastre di cemento-amianto utilizzando un forno industriale continuo [Brevetto (285) - Brevetto]
Abstract

This patent describes an industrial process for the direct complete temperature induced transformation (decomposition and recrystallization) of packages of plastic material containing roofing cement-asbestos slates or other asbestos containing wastes such as friable asbestos. The industrial firing process ensures a complete transformation of both the package and the asbestos containing material via a decomposition reaction of the organic compounds and a decomposition and recrystallization of all the inorganic mineral phases including the asbestos minerals.The firing process which ensures the total transformation of the packages and the mineral assemblage including the asbestos phases is accomplished using an industrial continuous tunnel kiln, with a technology comparable to that employed for the production of bricks or sanitary-wares. The length of the industrial kiln should be within 100 and 150 m to guarantee the proper firing cycle and total decomposition and recrystallization of both the hazardous serpentine and amphibole species of asbestos. The transformation via decomposition and recrystallization of these minerals leads to the formation of non hazardous crystalline Si-, Ca-; Mg-rich silicates. To this aim, the steps of the firing cycle which are required are:Step 1: a heating non-isothermal run up to the maximum firing temperature of 1200-1300 °C not shorter than 8 h;Step 2: an isotherm at the maximum firing temperature of 1200-1300 °C not shorter than 12 h;Step 3: a slow cooling non-isothermal run down to room temperature not shorter than 6 h.During the firing cycle, the industrial kiln must ensure complete isolation of the packages to be treated from the environment outside the kiln. All the volatile compounds and the asbestos fibres eventually released during the preliminary stage (Step 1) of the firing process inside the kiln will be conveyed to a post-combustion system (a supplementary heater at the top of the kiln) operating at temperature not lower than 1100 °C, to guarantee their complete thermal transformation and decomposition. The hot smokes and particulate from the post-combustor system will be successively cooled down to a temperature lower than 150 °C to allow the flow through double absolute HEPA filters before they are released in air.This industrial process is highly innovative and unique because it makes possible a safe direct thermal transformation of the packages containing the asbestos materials. The packages are not opened nor mechanically ground before the firing process. In this way, such pre-firing operations, highly dangerous because of possible dispersion of asbestos fibres in air, are avoided.The energy to the kiln will be supplied using natural gas.This industrial system will be capable to operate either with cement-asbestos sheets and friable asbestos and/or synthetic glass/wool fibers.As consequence of the thermal treatment, in agreement with the actual laws concerning the treatment and recycling of transformed asbestos containing wastes (see Table B Italian Minister Decree nr. 248, July 29th 2004), the product of transformation, composed of a mixture of innocuous non-fibrous crystalline silicates can be milled and recycled as a raw material for the formulation of a number of different industrial products such as traditional ceramics, pigments, cements and bricks.

Sciancalepore, C.; Gualtieri, A. F.; Scardi, P.; Flor, A.; Allia, P.; Tiberto, P.; Barrera, G.; Messori, M.; Bondoli, F. ( 2018 ) - Structural characterization and functional correlation of Fe3O4 nanocrystals obtained using 2-ethyl-1,3-hexanediol as innovative reactive solvent in non-hydrolytic sol-gel synthesis - MATERIALS CHEMISTRY AND PHYSICS - n. volume 1 - pp. da 337 a 349 ISSN: 0254-0584 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An original non-hydrolytic sol-gel approach, using 2-ethyl-1,3-hexanediol as reactive solvent, was proposed to synthetize nanostructured magnetite. Iron-oxide nanoparticles were prepared and studied as a function of the precursor-to-solvent ratio. The crystallization degree of nanoparticles was followed by the combined Rietveld and Reference Intensity Ratio method. This procedure has allowed the determination of both amorphous and crystalline content of nanomagnetite, using hematite as suitable internal standard. The results of Rietveld method show that the crystalline content decreases as the precursor-to-solvent is increased, ranging from 67 to 60 wt%. Information on the crystallite size-strain distribution and microstructural evolution of nanocrystals was supplied by line profile analysis of the powder diffraction patterns, employing the Whole Powder Pattern Modeling analysis: the obtained log-normal distribution curves become increasingly narrow and symmetrical, while nanoparticle microstrain increases as the precursor concentration is increased. The dimensional analysis of the Transmission Electron Microscopy images has allowed to obtain the nanoparticle grain-size distribution. Nanoparticle dimensions decreases from 15 to 9 nm increasing the precursor concentration. The comparison between the results of X-ray diffraction and microscopic characterization techniques highlighted the effect of several factors, such as size, shape and microstructure of magnetite nanoparticles, on their functional magnetic response. Magnetic characterizations show that magnetite nanoparticles are not in the superparamagnetic phase even at room temperature, independent of the precursor concentration. On the other hand, the room-temperature saturation magnetization, ranging from 73 to 60 emu/g, is a function of the nanoparticle average size, decreasing as the precursor concentration increases.

Nistor, M. M.; Cheval, S.; Gualtieri, A. F.; Dumitrescu, A.; Boţan, V. E.; Berni, A.; Hognogi, G.; Irimuş, I. A.; Porumb-Ghiurco, C. G. ( 2017 ) - Crop evapotranspiration assessment under climate change in the Pannonian basin during 1991–2050 - METEOROLOGICAL APPLICATIONS - n. volume 24 - pp. da 84 a 91 ISSN: 1469-8080 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The impact of climate on crop evapotranspiration (ETc) was assessed in the Pannonian basin for the present (1991–2020) and future (2021–2050). Annual temperature, annual precipitation and monthly potential evapotranspiration are the main climate data used in the present study. The European land cover database was used for the spatial recognition of terrain vegetation of the countries which are found in the Pannonian basin. A difference of maximum annual temperature from 19.9 to 20.8∘C was observed in the investigated area between 1991–2020 and 2021–2050. Precipitation rates decrease from west (1800 mm) to east (below 400 mm), and the potential evapotranspiration varies from 500 to 800 mm. Four stages of crop growth were identied and for each stage the crop co-efcients were assessed. For present projections of climate data, the annual c rop evapotranspiration variability is from 105 to 1087 mm and records the highest values in mid-season stage, ove r 630 mm. Future projections indicate that in the central and southern part of the Pannonian basin the annual crop evapotranspiration will increase. For both present and future projections, the lowest crop evapotranspiration was found in the cold season, because of lack of heat and lower values of the crop co-efficient.

Ballirano, P.; Bloise, A.; Gualtieri, A. F.; Lezzerini, M.; Pacella, A.; Perchiazzi, N.; Dogan, M.; Dogan, A. U. ( 2017 ) - Crystal structure of mineral fibres. ( - Mineral fibres: crystal chemistry, chemical-physical properties, biological interaction and toxicity. ) - n. volume 18 - pp. da 17 a 64 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This chapter deals with the crystal structure of regulated and unregulated mineral fibres. The aim is to provide readers, both specialists and researchers broadly interested in environmental problems, with up-to-date information on a topic that is expanding daily. The chapter describes specifically the structure of the fibrous modification whenever available and outlines possible differences from the corresponding prismatic variety. Details of the experimental techniques used for structure determination/refinement are reported also, if appropriate, to outline the experimental difficulties faced due to the small dimensions, sensitivity and chemical complexity of mineral fibres.

Gualtieri, Alessandro F. ( 2017 ) - Introduction [Mineral fibres] ( - Mineral fibres: crystal chemistry, chemical-physical properties, biological interaction and toxicity: university textbook ) (European Mineralogical Union London GBR ) - pp. da 1 a 16 ISBN: 9780903056656 ISSN: 1417-2917 [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This introductory chapter presents the state of the art in the multidisciplinary research field of asbestos and mineral fibres in general. The book describes the world of mineral fibres with its huge complexity and poorly understood, detrimental bio-chemical interaction with the human body. The approach of the chemist/mineralogist/ crystallographer adopts the perspective of the fibre itself (the invader of the body) whereas the approach of the bio-chemist/toxicologist/physician adopts the perspective of the organism (the invaded) interacting with the fibre. Both perspectives must be considered in synergy in an attempt to outline a conclusive model explaining the toxicity of mineral fibres, and provide a robust scientific basis that can be used by political and social partners to resolve finally the global issue of asbestos.

Viani, A.; Zbiri, M.; Bordallo, H. N.; Gualtieri, A. F.; Mácová, P. ( 2017 ) - Investigation of the Setting Reaction in Magnesium Phosphate Ceramics with Quasielastic Neutron Scattering. - JOURNAL OF PHYSICAL CHEMISTRY. C - n. volume 121 - pp. da 11355 a 11367 ISSN: 1932-7447 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Magnesium phosphate ceramics are a class of acid-base cements for bioengineering and civil engineering applications. We report on quasielastic neutron scattering results focusing on the evolution of the state of water in the system during the setting reaction, to shed light on the reaction mechanisms and the nature of the products. In the first few minutes, a consistent fraction of water molecules appears as immobile, and after a transient time, they start to be progressively bound into a reaction product. The kinetics of this last process has been described with an equation combining an Avrami model and a first-order reaction model with apparent activation energies of 18 and 6 kJ/mol, respectively. The results indicate that during the reaction the water molecules experience confinement effects inside a restricted space. The size of the confining volume decreases as the reaction progresses. It is proposed that an amorphous precursor with high surface area, bonding a relevant fraction of water, but also hosting mobile water, forms first. After an induction period, this phase undergoes further transformation into a product, still amorphous, considered as a further precursor of the final crystalline phase. With the reaction being kinetically driven, nonclassical mechanisms of nucleation and growth may lead to the formation of prenucleation clusters developing the first intermediate compound by coalescence. The mutating pH conditions trigger the transformation of the precursors, which likely contain structural motifs of the crystalline phase, similar to those observed in Ca and Zn, phosphate hydrate systems.

Gualtieri, Alessandro F.; Bursi Gandolfi, Nicola; Pollastri, Simone; Burghammer, Manfred; Tibaldi, Eva; Belpoggi, Fiorella; Pollok, Kilian; Langenhorst, Falko; Vigliaturo, Ruggero; Gorandražić, ( 2017 ) - New insights into the toxicity of mineral fibres: A combined in situ synchrotron μ-XRD and HR-TEM study of chrysotile, crocidolite, and erionite fibres found in the tissues of Sprague-Dawley rats - TOXICOLOGY LETTERS - n. volume 274 - pp. da 20 a 30 ISSN: 0378-4274 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Along the line of the recent research topic aimed at understanding the in vivo activity of mineral fibres and their mechanisms of toxicity, this work describes the morpho-chemical characteristics of the mineral fibres found in the tissues of Sprague-Dawley rats subjected to intraperitoneal/intrapleural injection of UICC chrysotile, UICC crocidolite and erionite-Na from Nevada (USA). The fibres are studied with in situ synchrotron powder diffraction and high resolution transmission electron microscopy to improve our understanding of the mechanisms of toxicity of these mineral fibres. In contact with the tissues of the rats, chrysotile fibres are prone to dissolve, with leaching of Mg and production of a silica rich relict. On the other hand, crocidolite and erionite-Na fibres are stable even for very long contact times within the tissues of the rats, showing just a thin dissolution amorphous halo. These findings support the model of a lower biopersistence of chrysotile with respect to crocidolite and erionite-Na but the formation of a silica-rich fibrous residue after the pseudo-amorphization of chrysotile may justify a higher cytotoxic potential and intense inflammatory activity of chrysotile in the short term in contact with the lung tissues.

Aretusini, S.; Mittempergher, S.; Plümper, O.; Spagnuolo, E.; Gualtieri, A. F.; Di Toro, G. ( 2017 ) - Production of nanoparticles during experimental deformation of smectite and implications for seismic slip - EARTH AND PLANETARY SCIENCE LETTERS - n. volume 463 - pp. da 221 a 231 ISSN: 0012-821X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Nanoparticles and amorphous materials are common constituents of the shallow sections of active faults. Understanding the conditions at which nanoparticles are produced and their effects on friction can further improve our understanding of fault mechanics and earthquake energy budgets. Here we present the results of 59 rotary shear experiments conducted at room humidity conditions on gouge consisting of mixtures of smectite (Ca-montmorillonite) and quartz. Experiments with 60, 50, 25, 0 wt.% Ca-montmorillonite, were performed to investigate the influence of variable clay content on nanoparticle production and their influence on frictional processes. All experiments were performed at a normal stress of 5 MPa, slip rate of , and at a displacement of 3 m. To monitor the development of fabric and the mineralogical changes during the experiments, we investigated the deformed gouges using scanning and transmission electron microscopy combined with X-ray powder diffraction quantitative phase analysis. This integrated analytical approach reveals that, at all slip rates and compositions, the nanoparticles (grain size of 10–50 nm) are partly amorphous and result from cataclasis, wear and mechanical solid-state amorphization of smectite. The maximum production of amorphous nanoparticle occurs in the intermediate slip rate range (), at the highest frictional work, and is associated to diffuse deformation and slip strengthening behavior. Instead, the lowest production of amorphous nanoparticles occurs at co-seismic slip rates (), at the highest frictional power and is associated with strain and heat localization and slip weakening behavior. Our findings suggest that, independently of the amount of smectite nanoparticles, they produce fault weakening only when typical co-seismic slip rates (>0.1 ms−1) are achieved. This implies that estimates of the fracture surface energy dissipated during earthquakes in natural faults might be extremely difficult to constrain.

Gualtieri, A. F. ( 2017 ) - Sharing different perspectives to understand asbestos-induced carcinogenesis: A comment to Jiang et al. (2016) - CANCER SCIENCE - n. volume 108 - pp. da 156 a 157 ISSN: 1349-7006 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This letter reports some constructive observations on the recent findings by Jiang et al. Cancer Sci (2016) that have inspired a more general comment on how the research on asbestos should take advantage of the different existing multidisciplinary perspectives so to flow into a final comprehensive model of asbestos-induced carcinogenesis.

Pollastri, Simone; Perchiazzi, Natale; Gigli, Lara; Ferretti, Paolo; Cavallo, Alessandro; Bursi Gandolfi, Nicola; Pollok, Kilian; Gualtieri, Alessandro F. ( 2017 ) - The crystal structure of mineral fibres. 2. Amosite and fibrous anthophyllite - PERIODICO DI MINERALOGIA - n. volume 86 - pp. da 55 a 65 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This study reports for the frst time crystal-structure data for amosite and fibrous anthophyllite. The chemical composition of the two fibre species was determined from EMPA. Crystal structures were refned using powder-diffraction data, using both laboratory sources and synchrotron radiation. Results were compared with the available literature data for the non-fibrous varieties grunerite and anthophyllite, respectively. The calculated site-occupancies for all samples are in agreement with the chemical compositions calculated from EMPA. The existing structure models of grunerite and orthorhombic anthophyllite also applies to the corresponding fibrous varieties amosite and fibrous anthophyllite, respectively. In amosite, both Fe 2+ and Fe 3+ atoms are found at the sites M(1), M(2) and M(3) and Fe 2+ ions is the only atomic species found at site M(4). Mg is disordered over the C sites with a preference for site M(2). Minor Ca and Na have been assigned to the A site. In fibrous anthophyllite, Mg is the only atomic species found at the M1, M2 and M3 sites. Fe 2+ , Mg (and minor Mn) have been assigned to the M4 site, whereas minor Ca has been assigned to the A site. In both structures, the environment at the M(4) site in amosite and M4 site in fibrous anthophyllite is highly distorted. This work can be considered a basis for studies aimed at understanding the potential toxicity/pathogenicity of these mineral fibres.

Pollastri, Simone; Gigli, Lara; Ferretti, Paolo; Andreozzi, Giovanni B.; Bursi Gandolfi, Nicola; Pollok, Kilian; Gualtieri, Alessandro F. ( 2017 ) - The crystal structure of mineral fibres. 3. Actinolite asbestos - PERIODICO DI MINERALOGIA - n. volume 86 - pp. da 89 a 98 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The present work reports chemical and structural data of actinolite asbestos from Aurina Valley, Bolzano (Italy). The chemical composition was determined using EMPA and TG analysis, and the Fe3+/Fetot ratio was accurately evaluated with independent 57Fe Mössbauer spectroscopy. Morphology and crystallinity were also investigated through SEM and TEM investigations. Crystal structure was refined using high-resolution synchrotron XRPD data. The iron content of Aurina Valley sample is lower compared to two representative asbestiform actinolite samples (with structure refinement) taken from the literature (FeOtot 7.77 wt% against 12÷13 wt%, respectively), accounting for the reduced cell volume here measured (910.29 ų against 912÷918 ų, respectively). Refined site scattering values of Aurina Valley sample are in agreement with those calculated from chemical compositions, and the optimized structural formula is: K0.02Na0.05(Na0.08Ca1.92)Ʃ=2.00(Mg3.80Fe2+0.79Fe3+0.11Al0.20Mn0.05Ni0.02Cr0.01)Ʃ=4.98(Si7.67Al0.25)Ʃ=7.92O21.69(OH)2.31. The C sites M(1), M(2) and M(3) are occupied by Mg and Fe in a proportion of ~4:1, whereas the M(4) site contains mainly Ca and a very small amount of Na. Iron exclusively occupies the octahedral C sites, with Fe 2+ ions occurring at the M(1,2,3) sites and the small amount of Fe 3+ (13% of Fe tot) ordered at the M(2) site. The refined crystal structure and cation distribution are fully consistent with results previously obtained on asbestiform and non-asbestiform samples belonging to the tremolite-actinolite-ferro– actinolite substitutional series.

Bloise, A.; Kusiorowski, R.; Lassinantti Gualtieri, M.; Gualtieri, A. F. ( 2017 ) - Thermal behaviour of mineral fibres ( - Mineral fibres: crystal chemistry, chemical-physical properties, biological interaction and toxicity. ) - pp. da 215 a 260 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This chapter deals with the synthesis and thermal stability ofmineral fibres. The different structural assemblages within mineral fibres and their resistance to high temperature changes fromspecies to species. In general, the formation of such minerals takes place in hydrothermal environments. The thermal decomposition process consists of three main stages: the loss of water adsorbed on the surface of the fibre and the zeolitic water below 200250ºC; the removal of the structure water (the hydroxyl groups) in the range 5001100ºC and recrystallization into new stable crystalline phases. The thermal stability of chrysotile, amphiboles fibres and erionite will be described in detail and will be followed by specific sections describing how the concept of thermal decomposition is used for the remediation of wastes containing asbestos to produce secondary raw materials to be recycled in various industrial application.

Gualtieri, A. F.; Mossman, B. T.; Roggli, V. L. ( 2017 ) - Towards a general model to predict the toxicity and pathogenicity of mineral fibres. ( - Mineral fibres: crystal chemistry, chemical-physical properties, biological interaction and toxicity. ) - pp. da 501 a 532 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

This chapter provides a comprehensive description of the physical, chemical, biological and mineralogical parameters that play a role in determining the toxicity and pathogenicity of mineral fibres. The first steps towards a general toxicity/pathogenicity model of mineral fibres are described here. Eventually the model can be generalized and may be applied to biodurable man-made mineral fibres and other natural and synthetic fibres in addition to silicates. Because of the complexity of the topic, a truly multidisciplinary approach is essential. A concept that will be stressed in the final notes of the chapter is that a full understanding of the toxicity/pathogenicity of mineral fibres aimed at finding effective solutions for the prevention and treatment of asbestos-related diseases can only be the outcome if an holistic approach is applied which takes advantage of synergistic research activity and communication between biochemists, mineralogists/crystallographers, pathologists, physicians, physicists and toxicologists, all sharing their distinct but interrelated perspectives. This is a great challenge for all such scientific individuals to work together to resolve and develop predictivemodels that incorporate their research findings and conclusions.

Bursi gandolfi, N.; Gualtieri, A. F.; Pollastri, S.; Tibaldi, E.; Belpoggi, F. ( 2016 ) - Assessment of asbestos body formation by high resolution FEG-SEM after exposure of Sprague-Dawley rats to chrysotile, crocidolite, or erionite - JOURNAL OF HAZARDOUS MATERIALS - n. volume 306 - pp. da 95 a 104 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work presents a comparative FEG-SEM study of the morphological and chemical characteristics of both asbestos bodies and fibres found in the tissues of Sprague-Dawley rats subjected to intraperitoneal or intrapleural injection of UICC chrysotile, UICC crocidolite and erionite from Jersey, Nevada (USA), with monitoring up to 3 years after exposure.Due to unequal dosing based on number of fibres per mass for chrysotile with respect to crocidolite and erionite, excessive fibre burden and fibre aggregation during injection that especially for chrysotile would likely not represent what humans would be exposed to, caution must be taken in extrapolating our results based on instillation in experimental animals to human inhalation. Notwithstanding, the results of this study may help to better understand the mechanism of formation of asbestos bodies.For chrysotile and crocidolite, asbestos bodies are systematically formed on long asbestos fibres. The number of coated fibres is only 3.3% in chrysotile inoculated tissues. In UICC crocidolite, Mg, Si, and Fe are associated with the fibres whereas Fe, P and Ca are associated with the coating. Even for crocidolite, most of the observed fibres are uncoated as coated fibres are about 5.7%. Asbestos bodies do not form on erionite fibres. The crystal habit, crystallinity and chemistry of all fibre species do not change with contact time, with the exception of chrysotile which shows signs of leaching of Mg.A model for the formation of asbestos bodies from mineral fibres is postulated. Because the three fibre species show limited signs of dissolution in the tissue, they cannot act as source of elements (primarily Fe, P and Ca) promoting nucleation and growth of asbestos bo dies. Hence, the limited number of coated fibres should be due to the lack of nutrients or organic nature.

Nistor, ; M., -M.; Gualtieri, A. F.; Cheval, S.; Dezsi, Ş.; Boţan, V. E. ( 2016 ) - Climate change effects on crop evapotranspiration in the Carpathian Region from 1961 to 2010 - METEOROLOGICAL APPLICATIONS - n. volume 23 - pp. da 462 a 469 ISSN: 1469-8080 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this study, the annual and seasonal crop evapotranspiration at the spatial level of the Carpathian Region were evaluated over 1961–2010. The temperature, precipitation and actual evapotranspiration grid monthly climate data and land cover were analysed and processed on a seasonal basis to compute the annual crop evapotranspiration. The land cover evapotranspiration rate was assigned through evapotranspiration coefficients from the literature. Geographical Information System (GIS) techniques, such as conversions from vector to raster data and the ‘Raster Calculator’ function, were used to assess the spatial distribution of the crop evapotranspiration at a regional scale. In particular, two datasets from different periods (1961–1990 and 1990–2010) were used to compute the seasonal and annual crop evapotranspiration for the Carpathian region. The results of climate parameters indicate a rise in temperature and crop evapotranspiration values between the first and the second period. In addition, significant spatial changes were observed with a shift of maximum values from south to north.

Carbone, Michele; Kanodia, Shreya; Chao, Ann; Miller, Aubrey; Wali, Anil; Weissman, David; Adjei, Alex; Baumann, Francine; Boffetta, Paolo; Md, ; Buck, Brenda; de Perrot, Marc; Umran Dogan, A.; Gavett, Steve; Gualtieri, Alessandro; Hassan, ; Hesdorffer, Mary; Hirsch, Fred R.; Larson, David; Mao, Weimin; Masten, Scott; Pass, Harvey I.; Peto, Julian; Pira, Enrico; Steele, Ian; Tsao, Anne; Alida Woodard, Gavitt; Yang, Haining; Malik, Shakun ( 2016 ) - Consensus Report of the 2015 Weinman International Conference on Mesothelioma - JOURNAL OF THORACIC ONCOLOGY - n. volume 11 - pp. da 1246 a 1262 ISSN: 1556-0864 [Articolo in rivista (262) - Articolo su rivista]
Abstract

On November 9 and 10, 2015, the International Conference on Mesothelioma in Populations Exposed to Naturally Occurring Asbestiform Fibers was held at the University of Hawaii Cancer Center in Honolulu, Hawaii. The meeting was cosponsored by the International Association for the Study of Lung Cancer, and the agenda was designed with significant input from staff at the U.S. National Cancer Institute and National Institute of Environmental Health Sciences. A multidisciplinary group of participants presented updates reflecting a range of disciplinary perspectives, including mineralogy, geology, epidemiology, toxicology, biochemistry, molecular biology, genetics, public health, and clinical oncology. The group identified knowledge gaps that are barriers to preventing and treating malignant mesothelioma (MM) and the required next steps to address barriers. This manuscript reports the group's efforts and focus on strategies to limit risk to the population and reduce the incidence of MM. Four main topics were explored: genetic risk, environmental exposure, biomarkers, and clinical interventions. Genetics plays a critical role in MM when the disease occurs in carriers of germline BRCA1 associated protein 1 mutations. Moreover, it appears likely that, in addition to BRCA1 associated protein 1, other yet unknown genetic variants may also influence the individual risk for development of MM, especially after exposure to asbestos and related mineral fibers. MM is an almost entirely preventable malignancy as it is most often caused by exposure to commercial asbestos or mineral fibers with asbestos-like health effects, such as erionite. In the past in North America and in Europe, the most prominent source of exposure was related to occupation. Present regulations have reduced occupational exposure in these countries; however, some people continue to be exposed to previously installed asbestos in older construction and other settings. Moreover, an increasing number of people are being exposed in rural areas that contain noncommercial asbestos, erionite, and other mineral fibers in soil or rock (termed naturally occurring asbestos [NOA] ) and are being developed. Public health authorities, scientists, residents, and other affected groups must work together in the areas where exposure to asbestos, including NOA, has been documented in the environment to mitigate or reduce this exposure. Although a blood biomarker validated to be effective for use in screening and identifying MM at an early stage in asbestos/NOA-exposed populations is not currently available, novel biomarkers presented at the meeting, such as high mobility group box 1 and fibulin-3, are promising. There was general agreement that current treatment for MM, which is based on surgery and standard chemotherapy, has a modest effect on the overall survival (OS), which remains dismal. Additionally, although much needed novel therapeutic approaches for MM are being developed and explored in clinical trials, there is a critical need to invest in prevention research, in which there is a great opportunity to reduce the incidence and mortality from MM.

Ventruti, Gennaro; Ventura, Giancarlo Della; Corriero, Nicola; Malferrari, Daniele; Gualtieri, Alessandro F.; Susta, Umberto; Lacalamita, Maria; Schingaro, Emanuela ( 2016 ) - In situ high-temperature X-ray diffraction and spectroscopic study of fibroferrite, FeOH(SO4)·5H2O - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 43(8) - pp. da 587 a 595 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal dehydration process of fibroferrite, FeOH(SO4)·5H2O, a secondary iron-bearing hydrous sulfate, was investigated by in situ high-temperature synchrotron X-ray powder diffraction (HT-XRPD), in situ high-temperature Fourier transform infrared spectroscopy (HT-FTIR) and thermal analysis (TGA-DTA) combined with evolved gas mass spectrometry. The data analysis allowed the determination of the stability fields and the reaction paths for this mineral as well as characterization of its high-temperature products. Five main endothermic peaks are observed in the DTA curve collected from room T up to 800 °C. Mass spectrometry of gases evolved during thermogravimetric analysis confirms that the first four mass loss steps are due to water emission, while the fifth is due to a dehydroxylation process; the final step is due to the decomposition of the remaining sulfate ion. The temperature behavior of the different phases occurring during the heating process was analyzed, and the induced structural changes are discussed. In particular, the crystal structure of a new phase, FeOH(SO4)·4H2O, appearing at about 80 °C due to release of one interstitial H2O molecule, was solved by ab initio real-space and reciprocal-space methods. This study contributes to further understanding of the dehydration mechanism and thermal stability of secondary sulfate minerals.

Viani, A.; Peréz-Estébanez, M.; Pollastri, S.; Gualtieri, A. F. ( 2016 ) - In situ synchrotron powder diffraction study of the setting reaction kinetics of magnesium-potassium phosphate cements - CEMENT AND CONCRETE RESEARCH - n. volume 79 - pp. da 344 a 352 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work reports a kinetic study of the formation of magnesium-potassium phosphate cements accomplished using in-situ synchrotron powder diffraction. The reaction: MgO + KH 2 PO 4 + 5H 2 O → MgKPO 4 · 6H 2 O was followed in situ in the attempt of contributing to explain the overall mechanism and assess the influence of periclase (MgO) grain size and calcination temperature (1400-1600 °C) on the reaction kinetics. Numerical kinetic parameters for the setting reaction have been provided for the first time. The best fit to the kinetic data was obtained using a weighted nonlinear model fitting method with two kinetic equations, representing two consecutive, partially overlapping processes. MgO decomposition could be described by a first order (F1) model followed by a Jander diffusion (D3) controlled model. Crystallization of the product of reaction was modelled using an Avrami model (A n ) followed by a first order (F1) chemical reaction. A reaction mechanism accounting for such results has been proposed.

Gualtieri, A. F.; Ricchi, A.; Lassinantti Gualtieri, M.; Maretti, S.; Tamburini, M. ( 2016 ) - Kinetic study of the drying process of clay bricks - JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY - n. volume 123 - pp. da 153 a 167 ISSN: 1388-6150 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work deals with the drying kinetics of three red clays with different mineralogical composition and grain size distribution used for the production of clay bricks. The kinetic study was performed using thermo-gravimetry (TG) in both non-isothermal and isothermal mode in the 50-200 °C range. To the knowledge of the authors, this is the first time that the drying process of clay bricks is studied using the TG method to present a general model at molecular scale of the phenomenon. The observed drying mechanism is composed of a fast initial step and a slow final step. The former is characterized by an Avrami-like mechanism with an Avrami coefficient n 1 comprised between 1 and 2. This kinetic parameter indicates a diffusive control in three dimensions with instantaneous or deceleratory nucleation and refers to desorption of adsorbed water from the surface of all mineral phases. The second step is also characterized by an Avrami-like mechanism with n 2 = 1 and points to a diffusion-controlled reaction in two dimensions, with instantaneous nucleation. This step involves dehydration of plastic clay minerals such as illite, smectite and IS through diffusion of water molecules within the two-dimensional interlayer. The apparent activation energies related to the first fast mechanism have similar values ( < 32 kJ mol -1 ) for all samples. The apparent activation energy E a for the second slower step is dependent upon the mineralogical composition and is > 35 kJ mol -1 . The dependency of the apparent activation energies on grain size distribution and sample mass was also assessed.

Conedera, M.; Bursi Gandolfi, N.; Ferretti, P.; Gualtieri, A. F.; Rocchetti, I. ( 2016 ) - Miniera di Pralongo. Una mineralizzazione cuprifera presso canal San Bovo (Valle del Vanoi, Trento). - RIVISTA MINERALOGICA ITALIANA - n. volume 2 - pp. da 90 a 119 ISSN: 0391-9641 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Miniera di Pralongo. Una mineralizzazione cuprifera presso canal San Bovo (Valle del Vanoi, Trento).

Nistor, M. M.; Har, N.; Marchetti Dori, S.; Bigi, S.; Gualtieri, A. F. ( 2016 ) - Progress in mineralogical quantitative analysis of rock samples: Application to quartzites from Denali National Park, Alaska Range (USA) - POWDER DIFFRACTION - n. volume 31 - pp. da 31 a 39 ISSN: 0885-7156 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work deals with the determination of the mineralogical composition of three quartzite samples, selected as case study to verify the viability and accuracy of various experimental techniques commonly used in geometallurgy and petrography for the determination of the mineralogical composition of rock samples. The investigated samples are from the North-Eastern side of the Denali National Park (Alaska Range, USA). The mineralogical phase abundance of the samples was determined by digitally assisted optical modal point counting, scanning electron microscopy (SEM) + energy dispersive spectroscopy (EDS) modal and digital image analysis, normative calculation from bulk chemistry calculation, and modal Rietveld X-ray powder diffraction. The results of our study indicate that the results provided by modal optical and SEM digitalized counting seem less accurate than the others. The determination with EDS mapping was found to be inaccurate only for one sample. Agreement was found between the X-ray diffraction estimates and bulk chemistry calculation. For both modal optical and SEM digitalized counting, the statistics was probably insufficient to provide accurate results. The estimates obtained from the various methods are compared with each other in the attempt to attain general indications on the precision, accuracy, advantages/disadvantages of each method.

Sturini, Michela; Speltini, Andrea; Maraschi, Federica; Profumo, Antonella; Tarantino, Serena; Gualtieri, Alessandro F.; Zema, Michele ( 2016 ) - Removal of fluoroquinolone contaminants from environmental waters on sepiolite and its photo-induced regeneration - CHEMOSPHERE - n. volume 150 - pp. da 686 a 693 ISSN: 0045-6535 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Sepiolite is studied as sorbent for removal of Fluoroquinolone (FQ) contaminants from water. Marbofloxacin (MAR) and Enrofloxacin (ENR) were chosen as model FQs since they are the two most commonly employed veterinary FQs in livestock farming in northern Italy. Adsorption experiments on two sepiolites (SP-1 and SSE16) were carried out in tap water at pH 7.5 to better mimic real conditions. The sorption experimental data were fitted by Freundlich, Langmuir and S-Logistic1 models. The latter better described MAR and ENR adsorptions. Adsorption capacities of SP-1 and SSE16, respectively, were 132 mg g−1 and 121 mg g−1 for MAR, and 112 mg g−1 and 93 mg g−1 for ENR. X-ray powder diffraction, performed on clay samples enriched with each FQ and on the pristine clays, showed no substantial differences between the two sepiolites and evidenced no significant structural changes after FQs uptake, as also verified by infrared spectroscopy. This indicates that adsorption occurs only on the external surface of the mineral and not in the intracrystalline microporosity, likely due to the interaction between the FQ carboxylic group and the sepiolite surface. For the first time solid-state photodegradation of the adsorbed FQs was investigated for regenerating the sorbent. Results showed that the adsorbed drugs are effectively photodegraded by solar light, thus allowing sepiolite to be reused. The efficiency of this material for remediation of contaminated water was proved on ditch water, collected downstream a swine farm, containing some tens of ng L−1 of MAR and ENR.

Pollastri, Simone; Gualtieri, Alessandro F.; Vigliaturo, Ruggero; Ignatyev, Konstantin; Strafella, Elisabetta; Pugnaloni, Armanda; Alessandrocroce, ( 2016 ) - Stability of mineral fibres in contact with human cell cultures. An in situ μXANES, μXRD and XRF iron mapping study - CHEMOSPHERE - n. volume 164 - pp. da 547 a 557 ISSN: 0045-6535 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Relevant mineral fibres of social and economic importance (chrysotile UICC, crocidolite UICC and a fibrous erionite from Jersey, Nevada, USA) were put in contact with cultured diploid human non-tumorigenic bronchial epithelial (Beas2B) and pleural transformed mesothelial (MeT5A) cells to test their cytotoxicity. Slides of each sample at different contact times up to 96 h were studied in situ using synchrotron XRF, μ-XRD and μ-XAS (I18 beamline, Diamond Light Source, UK) and TEM investigations. XRF maps of samples treated for 96 h evidenced that iron is still present within the chrysotile and crocidolite fibres and retained at the surface of the erionite fibres, indicating its null to minor mobilization in contact with cell media; this picture was confirmed by the results of XANES pre-edge analyses. μ-XRD and TEM data indicate greater morphological and crystallinity modifications occurring in chrysotile, whereas crocidolite and erionite show to be resistant in the biological environment. The contact of chrysotile with the cell cultures seems to lead to earlier amorphization, interpreted as the first dissolution step of these fibres. The formation of such silica-rich fibre skeleton may prompt the production of HO in synergy with surface iron species and could indicate that chrysotile may be much more reactive and cytotoxic in vitro in the (very) short term whereas the activity of crocidolite and erionite would be much more sluggish but persistent in the long term.

Bloise, Andrea; Catalano, Manuela; Barrese, Eugenio; Gualtieri, Alessandro; Bursi Gandolfi, Nicola; Capella, Silvana; Belluso, Elena ( 2016 ) - TG/DSC study of the thermal behaviour of hazardous mineral fibres - JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY - n. volume 123 - pp. da 2225 a 2239 ISSN: 1388-6150 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper reports a systematic and comparative study of the thermal behaviour of fibres of social, health, economic and industrial relevance using thermogravimetric and differential scanning calorimetry (TG/DSC). The mineral fibres selected for the study are: three chrysotile samples, crocidolite, tremolite asbestos, amosite, anthophyllite asbestos and asbestiform erionite. Powder X-ray diffraction and scanning electron microscopy were used for the characterization of the mineral fibres before and after heating at 1000 or 1100 °C to identify the products of the thermal decomposition at a microscopic and structural scale and characterize their thermal behaviour. TG/DSC data allowed the determination of the structural water content and temperature stability. Furthermore, thermal analysis provided a sensitive and reliable technique for the detection of small quantities of different mineral phases occurring as impurities. After thermal treatment, fibrous samples were completely transformed into various iron oxide, cristobalite and other silicate phases which preserved the original overall fibrous morphology (as pseudomorphosis). Only crocidolite at 1100 °C was partially melted, and an amorphous surface was observed.

Pollastri, Simone; Perchiazzi, Natale; Lezzerini, Marco; Plaisier, Jasper R.; Cavallo, Alessandro; Chiara Dalconi, Maria; Bursi Gandolfi, Nicola; Gualtieri, Alessandro F. ( 2016 ) - The crystal structure of mineral fibres. 1. Chrysotile - PERIODICO DI MINERALOGIA - n. volume 85 - pp. da 249 a 259 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work reports the results of the structural study of three representative chrysotile samples of different provenance (Canadian UICC, and Italian Balangero and Valmalenco). Chemical composition was determined using EMPA and TG data. An innovative wet cryo-milling procedure was used to powder the flexible and durable chrysotile fibres. X-ray powder diffraction patterns were collected using both conventional and nonconventional sources. Collected data were used for Rietveld structural refinements and results were compared with available literature data. The three samples display similar structure models, although small differences were detected in the position of the oxygen atoms. Both the structural refinements and spectroscopic investigations confirms that Fe 2+ and Fe 3+ atoms in chrysotile are located in the octahedral cavities only, substituting for Mg 2+ . Regarding the atom coordinates, UICC chrysotile is the closest to the model reported by Falini et al. (2004). About the lattice parameters, the Valmalenco chrysotile is the closest, if compared with the Balangero and UICC, to both the model proposed by Whittaker (1956a,b) and Falini et al. (2004). This work is intended as a basis for subsequent studies aimed at understanding the toxicity of these mineral fibres.

Bloise, A.; Barca, D.; Gualtieri, A. F.; Pollastri, S.; Belluso, E. ( 2016 ) - Trace elements in hazardous mineral fibres - ENVIRONMENTAL POLLUTION - n. volume 216 - pp. da 314 a 323 ISSN: 0269-7491 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Both occupational and environmental exposure to asbestos-mineral fibres can be associated with lung diseases. The pathogenic effects are related to the dimension, biopersistence and chemical composition of the fibres. In addition to the major mineral elements, mineral fibres contain trace elements and their content may play a role in fibre toxicity. To shed light on the role of trace elements in asbestos carcinogenesis, knowledge on their concentration in asbestos-mineral fibres is mandatory. It is possible that trace elements play a synergetic factor in the pathogenesis of diseases caused by the inhalation of mineral fibres. In this paper, the concentration levels of trace elements from three chrysotile samples, four amphibole asbestos samples (UICC amosite, UICC anthophyllite, UICC crocidolite and tremolite) and fibrous erionite from Jersey, Nevada (USA) were determined using inductively coupled plasma mass spectrometry (ICP-MS). For all samples, the following trace elements were measured: Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Sb, Cs, Ba, La, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U. Their distribution in the various mineral species is thoroughly discussed. The obtained results indicate that the amount of trace metals such as Mn, Cr, Co, Ni, Cu and Zn is higher in anthophyllite and chrysotile samples, whereas the amount of rare earth elements (REE) is higher in erionite and tremolite samples. The results of this work can be useful to the pathologists and biochemists who use asbestos minerals and fibrous erionite in-vitro studies as positive cyto- and geno-toxic standard references.

Gualtieri, A. F.; Nicola Bursi, Gandolfi; Simone, Pollastri; Kilian, Pollok; Falko, Langenhorst ( 2016 ) - Where is iron in erionite? A multidisciplinary study on fibrous erionite-Na from Jersey (Nevada, USA) - SCIENTIFIC REPORTS - n. volume 6 - pp. da 37981 a 37981 ISSN: 2045-2322 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Fibrous erionite is a mineral fibre of great concern but to date mechanisms by which it induces cyto- and geno-toxic damage, and especially the role of iron associated to this zeolite species, remain poorly understood. One of the reasons is that we still don’t know exactly where iron is in natural erionite. This work is focused on fibrous erionite-Na from Jersey (Nevada, USA) and attempts to draw a general model of occurrence of iron in erionite and relationship with toxicity mechanisms. It was found that iron is present as 6-fold coordinated Fe3+ not part of the zeolite structure. The heterogeneous nature of the sample was revealed as receptacle of different iron-bearing impurities (amorphous iron-rich nanoparticles, micro-particles of iron oxides/hydroxides, and flakes of nontronite). If iron is not part of the structure, its role should be considered irrelevant for erionite toxicity, and other factors like biopersistence should be invoked. An alternative perspective to the proposed model is that iron rich nano-particles and nontronite dissolve in the intracellular acidic environment, leaving a residue of iron atoms at specific surface sites anchored to the windows of the zeolite channels. These sites may be active later as low nuclearity groups.

Viani, A.; Pollastri, S.; Macova, P.; Palermo, A.; Peréz-Estébanez, M.; Gualtieri, A. F. ( 2016 ) - XANES and micro-Raman spectroscopy study of the barium titanosilicates BaTiSi2O7 and BaTiSi4O11 - APPLIED PHYSICS. A, MATERIALS SCIENCE & PROCESSING - n. volume 122 - pp. da 372 a 379 ISSN: 0947-8396 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The coordination environment around Ti4+ in the photoluminescent compound BaTiSi2O7 and in BaTiSi4O11 was investigated with X-ray absorption near-edge structure spectroscopy and micro-Raman spectroscopy. The presence of VTi in TiO5 pyramidal units with one short Ti–O bond involving the apical oxygen was detected in both compounds. Interpretation of the vibrational signal from the silicate framework suggested that BaTiSi4O11 is a metasilicate containing building units of SiO4 tetrahedra, which are larger than in other barium titanosilicates. These results confirmed the same structural environment of Ti4+ as recently disclosed by structure refinement of BaTiSi2O7 and provided new insights into the unknown structure of BaTiSi4O11 in the light of the study of its physical properties as potential functional material.

Ferretti, P.; Gualtieri, A. F.; Rocchetti, I.; Vecchi, F. ( 2015 ) - Cava Pralongo. Nuove segnalazioni dalle pegmatiti della Valle del Vanoi (Canal San Bovo, Trento). - RIVISTA MINERALOGICA ITALIANA - n. volume 3 - pp. da 164 a 185 ISSN: 0391-9641 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cava Pralongo. Nuove segnalazioni dalle pegmatiti della Valle del Vanoi (Canal San Bovo, Trento).

Remitti, F.; Smith, S. A. F.; Mittempergher, S.; Gualtieri, A. F.; Di Toro, G. ( 2015 ) - Frictional properties of fault zone gouges from the J-FAST drilling project (Mw9.0 2011 Tohoku-Oki earthquake) - GEOPHYSICAL RESEARCH LETTERS - n. volume 42 - pp. da 2691 a 2699 ISSN: 0094-8276 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Smectite-rich fault gouges recovered during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project (J-FAST)) from the plate boundary slip zone of the 2011 Mw 9.0 Tohoku-Oki earthquake were deformed at slip velocities of 10 µm s−1 to 3.5 m s−1 and normal stresses up to 12 MPa. Water-dampened gouges (1) are weaker (apparent friction coefficient, μ* <0.1) than room-humidity gouges (apparent friction coefficient, μ* ~0.1–0.35) at all slip velocities, (2) are velocity insensitive to velocity weakening at all slip velocities, unlike room-humidity gouges that are velocity strengthening at intermediate velocities (V = 0.001–0.1 m s−1), and (3) have negligible peak μ* at high slip velocities (V > 0.1 m s−1). A significant amount of amorphous material formed in room-humidity experiments at low- and high-slip velocities, likely by comminution and disordering of smectite. Our results indicate that the frictional properties of water-dampened gouges could have facilitated propagation of the Tohoku-oki rupture to the trench and large coseismic slip at shallow depths.

Ventruti, G.; Della Ventura, G.; Scordari, F.; Susta, U.; Gualtieri, A. F. ( 2015 ) - In situ high-temperature XRD and FTIR investigation of hohmannite, a water-rich Fe-sulfate, and its decomposition products - JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY - n. volume 119 - pp. da 1793 a 1802 ISSN: 1388-6150 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal dehydration of hohmannite, Fe 2 [O(SO 4 ) 2 ]·8H 2 O, a secondary iron-bearing hydrous sulfate, was investigated by in situ high-temperature X-ray powder diffraction and in situ high-temperature Fourier transform infrared spectroscopy. Combination of the data from both techniques allowed determining the stability fields and reaction paths for this mineral and its high temperature products. Five main dehydration/transformation steps for hohmannite have been identified in the heating range of 25-800 °C. Temperature behavior of the different phases was analyzed, and the heating-induced structural changes are discussed.

Tobaldi, D. M.; Pullar, R. C.; Gualtieri, A. F.; Belen Jorge, A.; Binions, R.; Mcmillan, P. F.; Seabraa, M. P.; Labrincha, J. A. ( 2015 ) - Influence of sol counter-ions on the anatase-to-rutile phase transformation and microstructure of nanocrystalline TiO2 - CRYSTENGCOMM - n. volume 17 - pp. da 1813 a 1825 ISSN: 1466-8033 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Amongst nanomaterials, metal oxides play an increasingly dominant role, with titanium dioxide (titania, TiO2) being widely used for various applications, such as light-to-energy conversion and storage, and photocatalysis. In this work, TiO2 has been synthesised via an aqueous sol–gel method, using three different mineral acids (HNO3, HCl and HBr) to peptise the sol, and hence provide counter-ions. Dried sols were thermally treated at three different temperatures (450, 600 and 800 °C), using three different dwell times (2, 4, and 8 h). Advanced X-ray methods were used to monitor the effect that the counter-ions had on the anatase-to-rutile phase transformation (ART). Quantitative phase analysis (QPA) using the Rietveld method was applied to assess the true amount of crystalline phases in the systems, and the amount of amorphous phase. Furthermore, the average crystalline domain diameter was also investigated, using whole powder pattern modelling (WPPM). With the advanced XRPD data (actual crystalline phase weight fraction in the samples and their average domain diameter and size distribution), it was possible to carry out a semi-quantitative study of the ART transformation kinetics. At a low temperature of 75 °C, the Cl− counter-ion was the most favourable to obtain anatase as the major crystalline phase, delaying the onset of the ART. Conversely, the Br− ions, maintained more anatase at 450 °C, with a lower ART rate. In general, halides were more effective in delaying the ART than NO3− counterions. Moreover, we observed an inverse linear relationship between the lattice volume expansion of rutile and the increase of its crystalline domain size at 450 and 600 °C isotherms. As the domain sizes increased with temperature, this effect reversed and became a direct linear dependence at the 800 °C isotherm, suggesting a critical size limit <90 nm for this effect.

Tobaldi, D. M.; Pullar, R. C.; Gualtieri, A. F.; Otero-Iruruet, G.; Singh, M. K.; Seabra, M. P.; Labrincha, J. A. ( 2015 ) - Nitrogen-modified nano-titania: True phase composition, microstructure and visible-light induced photocatalytic NOx abatement - JOURNAL OF SOLID STATE CHEMISTRY - n. volume 231 - pp. da 87 a 100 ISSN: 0022-4596 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Titanium dioxide (TiO2) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting ∼5% of the solar spectrum. Nitrification of titania to form N-doped TiO2 has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO2 to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO2 lattice using our green sol–gel nanosynthesis method, used to create 10 nm TiO2 NPs. Two parallel routes were studied to produce nitrogen-modified TiO2 nanoparticles (NPs), using HNO3+NH3 (acid-precipitated base-peptised) and NH4OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 °C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NOx) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NOx abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 °C, and NPs heated to 450 °C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO2 NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects of four simultaneous occurrences: (i) loss of OH groups and water adsorbed on the photocatalyst surface; (ii) growth of crystalline domain sizes with decrease in specific surface area; (iii) onset and progress of the ART; (iv) the increasing instability of the nitrogen in the titania lattice.

Lassinantti Gualtieri, E.M.; Romagnoli, M.; Gualtieri, A. ( 2015 ) - Preparation of phosphoric acid-based geopolymer foams using limestone as pore forming agent - Thermal properties by in situ XRPD and Rietveld refinements - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 35 - pp. da 3167 a 3178 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work, geopolymer foams were obtained by reacting metakaolin with phosphoric acid and using natural calcite/dolomite as foaming agent. Total porosity and thermal conductivity were ca. 70% and 0.083 ± 0.008 W/mK, respectively. Rietveld refinements, using both ex- and in situ XRPD data, were performed in order to elucidate the phase stability of the formed binder up to 1200°C. The results showed that the amorphous matrix partially crystallized in tridymite and cristobalite type structures of AlPO4-SiO2 solid solutions at about 700°C. At 1000 °C, 3:2 mullite started to crystallize, possibly from unreacted metakaolinite, resulting in co-crystallization of SiO2 cristobalite. At the same time, the amount of tridymite-type structure decreased, possibly due to selective phase transformation of AlPO4 tridymite to cristobalite, leaving behind the SiO2 isostructure. The geopolymer paste composition allows to tailor the mullite content in the refractory foam.

Sciancalepore, Corrado; Bondioli, Federica; Manfredini, Tiziano; Gualtieri, Alessandro ( 2015 ) - Quantitative phase analysis and microstructure characterization of magnetite nanocrystals obtained by microwave assisted non-hydrolytic sol–gel synthesis - MATERIALS CHARACTERIZATION - n. volume 100 - pp. da 88 a 97 ISSN: 1044-5803 [Articolo in rivista (262) - Articolo su rivista]
Abstract

An innovative preparation procedure, based on microwave assisted non-hydrolytic sol-gel synthesis, to obtain spherical magnetite nanoparticles was reported together with a detailed quantitative phase analysis and microstructure characterization of the synthetic products. The nanoparticle growth was analyzed as a function of the synthesis time and was described in terms of crystallization degree employing the Rietveld method on the magnetic nanostructured system for the determination of the amorphous content using hematite as internal standard. Product crystallinity increases as the microwave thermal treatment is increased and reaches very high percentages for synthesis times longer than 1 h. Microstructural evolution of nanocrystals was followed by the integral breadth methods to obtain information on the crystallite size-strain distribution. The results of diffraction line profile analysis were compared with nanoparticle grain distribution estimated by dimensional analysis of the transmission electron microscopy (TEM) images. A variation both in the average grain size and in the distribution of the coherently diffraction domains is evidenced, allowing to suppose a relationship between the two quantities. The traditional integral breadth methods have proven to be valid for a rapid assessment of the diffraction line broadening effects in the above-mentioned nanostructured systems and the basic assumption for the correct use of these methods are discussed as well.

Pugnaloni, Armanda; Lucarini, Guendalina; Rubini, Corrado; Smorlesi, Arianna; Tomasetti, Marco; Strafella, Elisabetta; Armeni, Tatiana; Gualtieri, Alessandro F. ( 2015 ) - Raw and thermally treated cement asbestos exerts different cytotoxicity effects on A549 cells in vitro - ACTA HISTOCHEMICA - n. volume 117 - pp. da 29 a 39 ISSN: 0065-1281 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Raw cement asbestos (RCA) undergoes a complete solid state transformation when heated at high temperatures. The secondary raw material produced, high temperatures-cement asbestos (HT-CA) is composed of newly-formed crystals in place of the asbestos fibers present in RCA. Our previous study showed that HT-CA exerts lower cytotoxic cell damage compared to RCA. Nevertheless further investigations are needed to deepen our understanding of pathogenic pathways involving oxidative and nitrative damage. Our aim is to deepen the understanding of the biological effects on A549 cells of these materials regarding DNA damage related proteins (p53, its isoform p73 and TRAIL) and nitric oxide (NO) production during inducible nitric oxide synthase (iNOS)-mediated inflammation. Increments of p53/p73 expression, iNOS positive cells and NO concentrations were found with RCA, compared to HT-CA and controls mainly at 48 h. Interestingly, ferrous iron causing reactive oxygen species (ROS)-mediated DNA damage was found in RCA as a contaminant. HT-CA thermal treatment induces a global recrystallization with iron in a crystal form poorly released in media. HT-CA slightly interferes with genome expression and exerts lower inflammatory potential compared to RCA on biological systems. It could represent a safe approach for storing or recycling asbestos and an environmentally friendly alternative to asbestos waste.

Viani, A.; Palermo, A.; Zanardi, S.; Demitri, N.; Petrícek, V.; Varini, F.; Belluso, E.; Ståhl, K.; Gualtieri, A. F. ( 2015 ) - Structure and stability of BaTiSi2O7 - ACTA CRYSTALLOGRAPHICA. SECTION B - n. volume 71 - pp. da 153 a 163 ISSN: 1600-5740 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Due to their optical, photo-luminescence (PL), and afterglow properties, barium titanosilicates are compounds of great interest for functional materials and light-emitting devices. Among them, BaTiSi2O7 (BTS2) is certainly one of the most intriguing; it displays peculiar properties (e.g. PL orange emission) whose exhaustive explanation has been hampered to date by the lack of a structure model. In this work, BTS2 and the related compound BaTiSi4O11 (BTS4) were synthesized through conventional solid-state reaction methods. BTS2 invariably shows complex twinning patterns. Thus, its structure solution and Rietveld structure refinement were attempted using synchrotron powder diffraction. BTS2 was found to be an intergrowth of monoclinic and triclinic crystals. The monoclinic phase has the space group P21/n and unit cell a = 7.9836 (3), b = 10.0084 (4), c = 7.4795 (3) Å, and [beta] = 100.321 (3)°, whereas the triclinic phase has the space group P\bar 1 and unit cell a = 7.99385 (4), b = 10.01017 (5), c = 7.47514 (3) Å, [alpha] = 90.084 (8), [beta] = 100.368 (8) and [gamma] = 89.937 (9)°. These lattices can be seen as a distortion of that of tetragonal synthetic [beta]-BaVSi2O7 with Ti in place of V. The structure models obtained from this study confirm the presence of fivefold coordinated Ti atoms in a distorted pyramidal configuration. The proposed solution supports existing theories for the explanation of the PL orange colour in BTS2.

Pollastri, Simone; D’Acapito, Francesco; Trapananti, Angela; Colantoni, Ivan; Andreozzi, Giovanni B.; Gualtieri, Alessandro F. ( 2015 ) - The chemical environment of iron in mineral fibres. A combined X-ray absorption and Mössbauer spectroscopic study - JOURNAL OF HAZARDOUS MATERIALS - n. volume 298 - pp. da 282 a 293 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Although asbestos represents today one of the most harmful contaminant on Earth, in 72% of the countries worldwide only amphiboles are banned while controlled use of chrysotile is allowed. Uncertainty on the potential toxicity of chrysotile is due to the fact that the mechanisms by which mineral fibres induces cyto- and geno-toxic damage are still unclear. We have recently started a long term project aimed at the systematic investigation of the crystal-chemistry, bio-interaction and toxicity of the mineral fibres. This work presents a systematic structural investigation of iron in asbestos and erionite (considered the most relevant mineral fibres of social and/or economic-industrial importance) using synchrotron X-ray absorption and Mössbauer spectroscopy. In all investigated mineral fibres, iron in the bulk structure is found in octahedral sites and can be made available at the surface via fibre dissolution. We postulate that the amount of hydroxyl radicals released by the fibers depends, among other factors, upon their dissolution rate; in relation to this, a ranking of ability of asbestos fibres to generate hydroxyl radicals, resulting from available surface iron, is advanced: amosite > crocidolite ≈ chrysotile > anthophyllite > tremolite. Erionite, with a fairly high toxicity potential, contains only octahedrally coordinated Fe3+. Although it needs further experimental evidence, such available surface iron may be present as oxide nanoparticles coating and can be a direct cause of generation of hydroxyl radicals when such coating dissolves.

GUALTIERI, Alessandro; Riva, Vincenzo; Bresciani, Andrea; Maretti, Stefano; Tamburini, Marco; Viani, Alberto ( 2014 ) - Accuracy in quantitative phase analysis of mixtures with large amorphous contents. The case of stoneware ceramics and bricks - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 47 - pp. da 835 a 846 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

For the first time, this work inspects the accuracy of quantitative phase analysis of both crystalline and amorphous components of stoneware tiles and bricks. A number of variables were considered: the nature of the internal standard, experimental conditions and counting statistics. The so-called G-factor method has also been applied. The results of the X-ray powder diffraction analysis have been compared with the results obtained with optical microscopy and image analysis. Only the mixtures spiked with corundum and silicon yielded accurate weight estimates of the amorphous fraction, whereas the use of highly X-ray absorbing internal standards (such as fluorite, rutile and zincite) resulted in gross underestimations. In fact, microabsorption effects are found to drastically reduce the accuracy of the results when standards with linear X-ray absorption coefficients higher than 100 cm-1 are employed. It was found that very low counting statistics reduced the calculated amorphous fractions in both bricks and stoneware tiles owing to partial masking of the major peak of the internal standard, namely corundum. The application of the G-factor method to the systems investigated was also evaluated. The results are poorer than those obtained using the internal standard.

Secco, Michele; Peruzzo, Luca; Palasse, Laurie; Artioli, Gilberto; Viani, Alberto; GUALTIERI, Alessandro ( 2014 ) - Crystal chemistry of clinker relicts from aged cementitious materials - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 47 - pp. da 1626 a 1637 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Despite the general tendency to consider Portland cement virtually fully hydrated within a few years, the occurrence of non-reacted clinker phases in cementitious materials that are several decades old is rather common. In this work, the integration of microstructural analysis by scanning electron microscopy and quantitative microchemical and micromineralogical characterization techniques, such as electron microprobe analysis and electron backscatter diffraction, allowed the definition of the crystal-chemical properties of partially hydrated cement residuals within different types of aged cementitious materials. The results on several clinker relicts show that the calcium silicate phases are transformed systematically and pervasively by hydration reactions, whereas the aluminate and ferrite phases do frequently persist in the anhydrous state. These relict phases may be distinguished through their peculiar chemical, mineralogical and textural features. These observations raise interesting questions concerning the long-term hydration kinetics of clinker phases and the durability behaviour of cementitious materials in operating conditions.

GUALTIERI, Alessandro; POLLASTRI, SIMONE; RONCHETTI, Francesco; Gandolfi, N. B.; Albonico, C.; Cavallo, A.; Zanetti, G.; Marini, P.; Sala, O. ( 2014 ) - Determination of the concentration of asbestos minerals in highly contaminated mine tailings: An example from abandoned mine waste of Cretaz and Emarese (Valle d'Aosta, Italy) - AMERICAN MINERALOGIST - n. volume 99 - pp. da 1233 a 1247 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

For the first time, this work reports concentration maps of asbestos minerals in contaminated mine tailings drawn using the results of Rietveld quantitative phase analysis (QPA). The investigated sites are located in the Valle d’Aosta region (Italy): Crètaz, the most important Italian magnetite mine, active until 1979 and Emarèse, one the most important chrysotile asbestos mines in Italy, active until 1968. The results of the study permit to draw the spatial distribution of the asbestos (chrysotile and tremolite in this specific case) concentration, useful to plan reclamation of the sites, with priority given to the areas with the highest asbestos concentration. Because of the complexity of the mineral assemblage, which includes, among the others, antigorite, chlorite, talc, and tremolite, the concentration of chrysotile was cross-checked using different experimental techniques such as X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), polarized light optical microscopy (PCOM), and differential thermal analysis (DTA). The accuracy of the results was validated by analyzing standard samples with known concentrations of chrysotile and tremolite. The comparison allowed to point out the advantages and disadvantages of each experimental method. At Crètaz, chrysotile ranges from 4.4 to 22.8 wt% and tremolite from 1.0 to 10.3 wt%, whereas at Emarèse the concentration of chrysotile varies from 3.3 to 39.5 wt% and tremolite from 5.9 to 12.4 wt%. Antigorite and chlorite are the major accompanying phases with variable amounts of other accessory minerals including magnetite, carbonates, talc, olivine, pyroxene, talc, and brucite. The results of our study are of key importance for the local environmental policies as the knowledge of the spatial distribution of the asbestos concentration allows to plan a detailed reclamation agenda of the contaminated sites. The spots with the highest surface contamination of both chrysotile and tremolite were identified and classified as priority areas in the reclamation plan.

Remitti, F.; Smith, S.; Gualtieri, A.; Di Toro, G.; Nielsen, S. ( 2014 ) - Frictional properties of fault rocks along the shallow part of the JapanTrench décollement: insights from samples recovered during the Integrated Ocean Drilling Project Expedition 343 (the JFAST project). ( EGU General Assembly 2014 - Wien - 27 April – 02 May 2014) ( - EGU General Assembly 2014 ) - GEOPHYSICAL RESEARCH ABSTRACTS - n. volume 16 [Abstract in rivista (266) - Abstract in Rivista]
Abstract

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Magdalena Lassinantti Gualtieri;Marcello Romagnoli;Simone Pollastri;Alessandro F. Gualtieri ( 2014 ) - Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties - CEMENT AND CONCRETE RESEARCH - n. volume 67 - pp. da 259 a 270 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties.

E. Zepeda-Alarcon, H. Nakotte; GUALTIERI, Alessandro; G. King, K. Page, S. C. Vogel, H.-W. Wang and H.-R. Wenk ( 2014 ) - Magnetic and nuclear structure of goethite (α-FeOOH): a neutron diffraction study - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 47 - pp. da 1983 a 1991 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The magnetic structure of two natural samples of goethite ([alpha]-FeOOH) with varying crystallinity was analyzed at 15 and 300 K by neutron diffraction. The well crystallized sample has the Pb'nm color space group and remained antiferromagnetic up to 300 K, with spins aligned parallel to the c axis. The purely magnetic 100 peak, identifying this color space group, was clearly resolved. The nanocrystalline sample shows a phase transition to the paramagnetic state at a temperature below 300 K. This lowering of the Néel temperature may be explained by the interaction of magnetic clusters within particles. The nuclear structure, refined with the Rietveld and pair distribution function methods, is consistent with reports in the literature.

Viani, Alberto; GUALTIERI, Alessandro ( 2014 ) - Preparation of magnesium phosphate cement by recycling the product of thermal transformation of asbestos containing wastes - CEMENT AND CONCRETE RESEARCH - n. volume 58 - pp. da 56 a 66 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Asbestos containing wastes have been employed for the first time in the formulation of magnesium phosphate cements. Two samples were mixed with magnesium carbonate and calcined at 1100 and 1300 °C. Under these conditions, complete destruction of asbestos minerals is known to occur. The product, containing MgO, after reaction with water-soluble potassium di-hydrogen phosphate, led to the formation of hydrated phases at room temperature. Crystalline and amorphous reaction products were detected, with the latter being likely the metastable precursor of the former. Measured strengths were found to be in line with data from the literature, suggesting that this material may be used as cement. The process here described represents a viable recycling opportunity for this class of hazardous wastes. Simultaneous destruction of asbestos minerals and formation of reactive MgO during thermal treatment, bring benefits in terms of energy requirements and preservation of natural resources in cement manufacturing.

Tobaldi, D. M.; Piccirillo, C.; Pullar, R. C.; GUALTIERI, Alessandro; Seabra, M. P.; Castro, P. M. L.; Labrincha, J. A. ( 2014 ) - Silver-Modified Nano-titania as an Antibacterial Agent and Photocatalyst - JOURNAL OF PHYSICAL CHEMISTRY. C - n. volume 118 - pp. da 4751 a 4766 ISSN: 1932-7447 [Articolo in rivista (262) - Articolo su rivista]
Abstract

With the increasing demand for nanomaterials, it is essential that they are produced, where possible, by sustainable or “green” synthesis methods, avoiding environmentally harmful processes and solvents, with the aim of reducing the production of hazardous byproducts and wastes and minimizing environmental impact. In this work, Ag-modified titania nanoparticles (NPs) were synthesized via a green aqueous sol–gel method. The products of the synthesis were thermally treated at 450 and 600 °C, and their photocatalytic (in liquid–solid and gas–solid phases) and antibacterial properties were assessed using both UV- and visible-light exposure. The microstructure and phase composition of the prepared samples were also characterized using advanced X-ray powder diffraction methods (whole powder pattern modeling). Results showed that both the amount of Ag and the thermal treatment greatly influenced not only the phase composition and microstructure but also the functional properties of the TiO2. The increasing levels of Ag retarded the anatase-to-rutile phase transition to a greater extent, and 2 mol % was the optimum amount of Ag for methylene blue photodegradation with both UV- and visible-light irradiation. When using a UV-light source, samples showed a much greater antibacterial activity toward Escherichia coli (E. coli; Gram-negative) than methicillin-resistant Staphylococcus aureous (Gram-positive). It was observed that UV light caused a change in the oxidation state of silver, from ionic silver to metallic (Ag+ → Ag0 NPs), this being detrimental for the antibacterial activity. However, under artificial white light irradiation this did not occur and the material kept its excellent antibacterial properties (higher activity than commercial P25); because of this, it could be suitable for use in health care, helping to greatly reduce the spread of Gram-negative type bacteria such as E. coli.

POLLASTRI, SIMONE; GUALTIERI, Alessandro; GUALTIERI, Eva Magdalena; HANUSKOVA', Miriam; Cavallo, Alessandro; Gaudino, Giovanni ( 2014 ) - The zeta potential of mineral fibres - JOURNAL OF HAZARDOUS MATERIALS - n. volume 276 [Articolo in rivista (262) - Articolo su rivista]
Abstract

For the first time, the zeta (ξ) potential of pathogenic mineral fibres (chrysotiles, amphiboles and erionite) was systematically investigated to shed light on the relationship between surface reactivity and fibre pathogenicity. A general model explaining the zeta potential of chrysotile, amphiboles and erionite has been postulated. In double distilled water, chrysotiles showed positive values while crocidolite and erionite showed negative values. In contact with organic solutions, all fibres exhibited negative values of zeta potential. The decrease of the surface potential is deemed to be a defensive chemical response of the macrophage cells to minimize hemolytic damage. Negatively charged surfaces favour the binding of collagen and redox activated Fe-rich proteins, to form the so-called asbestos bodies and prompt the formation of HO via the reaction with peroxide (H2O2+e(-)→HO+HO(-)). An additional mechanism accounting for higher carcinogenicity is possibly related to the Ca(2+) sequestration by the fibres with surface negative potential, impairing the mitochondrial apoptotic pathway. It was also found that with a negative zeta potential, the attractive forces prevailed over repulsions and favoured processes such as agglomeration responsible of a tumorigenic chronic inflammation.

Bernasconi, Andrea; Dapiaggi, Monica; GUALTIERI, Alessandro ( 2013 ) - Accuracy in quantitative phase analysis of mixtures with large amorphous contents. The case of zircon-rich sanitary-ware glazes - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 47 - pp. da 136 a 145 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The accuracy of quantitative phase analysis (QPA) of samples with dominant amorphous content, reproducing zircon-rich sanitary-ware glazes, has been investigated. X-ray powder diffraction (XRPD) methods were applied using both conventional Cu K[alpha] radiation and high-resolution synchrotron data. In this work, a combination of the reference intensity ratio (RIR) and Rietveld methods was applied to an artificial mixture (90 wt% glass, 10 wt% zircon), taking into account some of the most common effects that may affect the accuracy in amorphous quantification, such as the degree of crystallinity of the phases, microabsorption and sample preparation. Certified NIST SRM 676a ([alpha]-Al2O3) [Cline, Von Dreele, Winburn, Stephens & Filliben (2011). Acta Cryst. A67, 357-367] was used to quantify the amorphous content in zircon and in the different internal standards commonly used when a certified standard is not available or not applicable: the results show that all of the phases invariably contain amorphous material in the range 2.0-15.0 wt%. If the amorphous content of the standard is taken into account, the accuracy of the QPA of the artificial mixture is improved. It was observed that the Brindley correction for microabsorption does not significantly improve the results. Care must be applied if grinding time is increased, since this may increase the amorphous content in the sample. Finally, the sensitivity of the RIR-Rietveld method to the addition of a small amount of zircon (~1 wt%) has been considered, showing that accurate results can be achieved if great care is taken in the sample preparation and refinement strategy.

Marcello Romagnoli;Magdalena Lassinantti Gualtieri;Alessandro F. Gualtieri; Reimondas Šliteris; Rymantas Kažys; Giuliano Tari ( 2013 ) - Anisotropy of green stoneware evaluated by ultrasound measurements in combination with texture analyses - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 33 - pp. da 2785 a 2792 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Anisotropic microstructure of uniaxially pressed powders has been reported in the literature, and is often reflected in direction-dependent physical properties such as thermal conductivity and firing shrinkage. Quantification of direction-dependency could be an important tool to predict such physical variations. For the first time, an ultrasound technique in combination with a microstructural investigation were applied to access anisotropy in green uniaxially pressed stoneware tiles. The longitudinal ultrasound wave velocity was measured parallel and perpendicular to the pressing direction. The sample microstructure was investigated by scanning electron microscopy, porosimetry and X-ray powder diffraction analyses in combination with crystallographic texture analyses using the Rietveld method. It was found that the anisotropic character, quantified as the ratio between the velocities measured perpendicular and parallel to the pressing direction, increased with increasing compact density. Based on the microstructure analyses, these results were attributed to texture of the porous structure as well as the constituting minerals.

Viani, A.; GUALTIERI, Alessandro; Secco, M.; Peruzzo, L.; Artioli, G.; Cruciani, G. ( 2013 ) - Crystal chemistry of cement-asbestos - AMERICAN MINERALOGIST - n. volume 98 - pp. da 1095 a 1105 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

A study of a representative number of cement-asbestos (CA) samples removed from different localities in Italy has been accomplished with a combination of analytical techniques, including XRF, XRPD, SEM/EDS, micro-Raman, and electron backscattered diffraction (EBSD), to elucidate the mineralogical and chemical variability of this class of building materials on a large scale. We describe a complex mineralogy including phases of cement hydration, residual non-hydrated components, and a relevant fraction attributed to various processes of deterioration. With the aid of the CaO-MgO-SiO2 compositional diagram, three groups of CAs have been identified on the basis of their chemical parameters. This result is important for environmental and waste management issues.

Viani, Alberto; GUALTIERI, Alessandro; POLLASTRI, SIMONE; Rinaudo, Caterina; Croce, Alessandro; URSO, Giancarlo ( 2013 ) - Crystal chemistry of the high temperature product of transformation of cement-asbestos - JOURNAL OF HAZARDOUS MATERIALS - n. volume 248-249 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work, the high-temperature inertization product of a representative batch of samples of cement-asbestos (CA) from different localities in Italy have been characterized with a multidisciplinary approach. All the raw CA samples were heated at 1200°C for 15 min. After firing, they underwent a series of solid state reactions leading to global structural changes of the matrix. Effects of annealing time and temperature on the crystallization kinetics were thoroughly investigated. Both factors acted in favour of equilibrium. Three classes of CA were identified with the aid of phase diagrams and of specific plots relating chemical and mineralogical parameters. This result was considered of importance in view of the potential use of transformed cement-asbestos as a secondary raw material. In principle, the content of CA packages removed from the environment and their corresponding heat-treated products can be classified simply using XRF. This method allows for the selection of appropriate fractions in function of the most suitable recycling solution adopted. Samples belonging to the class called larnite-rich, turned out to be of great interest as possible candidate for substituting a fraction of cement in many building materials and innovative green cement productions.

GUALTIERI, Alessandro; Canovi, Lorenzo; Viani, Alberto; Bertocchi, Paolo; Corradini, Cecilia; Gualtieri, Eva Magdalena; GAZZADI, Gian Carlo; ZAPPAROLI, Mauro; Berthier, Serge ( 2013 ) - Mechanism of lustre formation in scheelite-based glazes - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 33 - pp. da 2055 a 2064 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work elucidates the mechanism responsible for the lustre effect of scheelite-based glazes for single-firing wall tiles. The surface decoration is obtained with a thin film composed of a Si–Ca–Zn–Al–K–B frit and 10 wt% WO3 on zircon-engobed substrates for single-firing wall tiles (maximum temperature of 1130 °C for 50 min). The observed lustre effect is sub-adamantine and pearlescent. It is sub-adamantine because scheelite nanocrystals at the surface, with a relatively high refractive index (n = 1.93), cause considerable reflection of light. The lustre is also weakly pearlescent because the nano-crystals oriented with the (004) plane parallel to the surface give interference with the underlying glassy layer (n ≈ 1.5), where randomly dispersed scheelite crystals occur. This model apparently applies to the glazes decorated with ceria, although the latter exhibits iridescence due to the high refractive index of ceria (n = 2.05) which yields stronger interference effect with the underlying glassy substrate.

Tobaldi, D.M.; Pullar, R.C.; GUALTIERI, Alessandro; Seabra, M.P.; Labrincha, J.A. ( 2013 ) - Phase composition, crystal structure and microstructure of silver and tungsten doped TiO2 nanopowders with tuneable photochromic behaviour - ACTA MATERIALIA - n. volume 61 - pp. da 5571 a 5585 ISSN: 1359-6454 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Titanium dioxide exists in a large number of polymorphs, the most common ones being, in order of abundance, rutile, anatase and brookite. Recently, there has been an increasing degree of attention on TiO2, due to its photocatalytic and antibacterial properties. In this work, titania nanopowders synthesized via an aqueous sol–gel method were modified with silver and/or tungsten, with potential application as photocatalysts and antibacterial agents. The dried gels were thermally treated at two temperatures, and the occurrence of amorphous phase—in both dried and calcined gels—was obtained using the Rietveld method. In powders calcined at 600 °C, the crystal structure of rutile was determined with the Rietveld method on the full profile fitting of the X-ray powder diffraction patterns, while microstructural information was achieved by means of Williamson–Hall plots and line broadening analysis methods. The photochromic property of the Ag and W/Ag modified samples—when subjected to both UV- and visible-light irradiation and for different time exposures—was also investigated via UV–Vis spectroscopy. Powders were shown to possess a tuneable photochromism due to the surface plasmon resonance of the added silver, depending on the firing temperature, light (and time) exposure, and on whether or not tungsten was present in the nanopowders.

GUALTIERI, Alessandro, C. Giacobbe, C. Rinaudo, A. Croce, M. Allegrina, G. Gaudino, H. Yang, M, Carbone ( 2013 ) - Preliminary results of the spectroscopic and structural characterization of mesothelioma inducing crocidolite fibers injected in mice - PERIODICO DI MINERALOGIA - n. volume 82(2) - pp. da 299 a 312 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

To investigate the structure and microstructure changes of crocidolite asbestos incorporated in biological tissues, fibers of this mineral phase were injected in mice peritoneum. Histological sections of different organs of mice developing mesothelioma after crocidolite inoculation were prepared and analysed by optical microscopy. The tumours developed within the peritoneal cavity, wrapped around the surrounding organs. Many fibres were observed in the fibrotic areas of the peritoneum lining pancreas and spleen. The raw fibers before inoculation and those embedded in mice tissues were characterized using Micro-Raman spectroscopy and in situ synchrotron X-ray diffraction at ESRF- Grenoble. Preliminary results indicate shifts of some bands on the Raman spectra and enlargement of the X-Ray diffraction peaks of the fibers localized in the mice tissue sections. A preliminary structural picture of the fibers incorporated in mice tissues suggests inter-crystalline migration of the iron and sodium ions.

Gualtieri, Alessandro ( 2013 ) - Recycling asbestos containing material (ACM) from construction and demolition waste (CDW) ( - Handbook of Recycled Concrete and Demolition Waste ) (Woodhead Publishing Cambridge (UK) GBR ) - pp. da 500 a 525 ISBN: 0857096907 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Asbestos containing materials (ACMs) are a class of hazardous waste ...

Viani, Alberto; GUALTIERI, Alessandro ( 2013 ) - Recycling the product of thermal transformation of cement-asbestos for the preparation of calcium sulfoaluminate clinker - JOURNAL OF HAZARDOUS MATERIALS - n. volume 260 [Articolo in rivista (262) - Articolo su rivista]
Abstract

According to recent resolutions of the European Parliament (2012/2065(INI)), the need for environmentally friendly alternative solutions to landfill disposal of hazardous wastes, such as asbestos-containing materials, prompts their recycling as secondary raw materials (end of waste concept). In this respect, for the first time, we report the recycling of the high temperature product of cement-asbestos, in the formulation of calcium sulfoaluminate cement clinkers (novel cementitious binders designed to reduce CO₂ emissions), as a continuation of a previous work on their systematic characterization. Up to 29 wt% of the secondary raw material was successfully introduced into the raw mix. Different clinker samples were obtained at 1250 °C and 1300 °C, reproducing the phase composition of industrial analogues. As an alternative source of Ca and Si, this secondary raw material allows for a reduction of the CO₂ emissions in cement production, mitigating the ecological impact of cement manufacturing, and reducing the need for natural resources.

Tobaldi, D.M.; Pullar, R.C.; GUALTIERI, Alessandro; Seabra, M.P.; Labrincha, J.A. ( 2013 ) - Sol–gel synthesis, characterisation and photocatalytic activity of pure, W-, Ag- and W/Ag co-doped TiO2 nanopowders - CHEMICAL ENGINEERING JOURNAL - n. volume 214 - pp. da 364 a 375 ISSN: 1385-8947 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Tungsten, silver and tungsten/silver co-doped titania nanopowders were synthesised via an aqueous sol–gel method. The size distribution and zeta potential of the starting sols were determined via photon correlation spectroscopy (PCS). The dried gels were thermally treated at two different temperatures, and the occurrence of amorphous phase was assessed using the combined Rietveld–RIR X-ray powder diffraction method. A systematic study of the optical properties of the powders was made with diffuse reflectance spectroscopy (DRS), and the energy band gaps were calculated using the differential reflectance method; while their morphology was investigated using electron microscopy analysis (TEM). The photocatalytic activity of the samples was assessed in liquid–solid phase, under UVA-light and visible-light irradiation, monitoring the degradation of an organic dye. The influence of the phase composition, optical properties, dimensions, and specific surface area of the powders on the photocatalytic activity was thoroughly discussed.

Ventruti, Gennaro; Scordari, Fernando; Ventura, Giancarlo Della; Bellatreccia, Fabio; GUALTIERI, Alessandro; Lausi, Andrea ( 2013 ) - The thermal stability of sideronatrite and its decomposition products in the system Na2O–Fe2O3–SO2–H2O - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 40 - pp. da 659 a 670 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal stability of sideronatrite, ideally Na2Fe3+(SO4)2(OH)·3(H2O), and its decomposition products were investigated by combining thermogravimetric and differential thermal analysis, in situ high-temperature X-ray powder diffraction (HT-XRPD) and Fourier transform infrared spectroscopy (HT-FTIR). The data show that for increasing temperature there are four main dehydration/transformation steps in sideronatrite: (a) between 30 and 40 °C sideronatrite transforms into metasideronatrite after the loss of two water molecules; both XRD and FTIR suggest that this transformation occurs via minor adjustments in the building block. (b) between 120 and 300 °C metasideronatrite transforms into metasideronatrite II, a still poorly characterized phase with possible orthorhombic symmetry, consequently to the loss of an additional water molecule; X-ray diffraction data suggest that metasideronatrite disappears from the assemblage above 175 °C. (c) between 315 and 415 °C metasideronatrite II transforms into the anhydrous Na3Fe(SO4)3 compound. This step occurs via the loss of hydroxyl groups that involves the breakdown of the [Fe3+(SO4)2(OH)] ∞ 2− chains and the formation of an intermediate transient amorphous phase precursor of Na3Fe(SO4)3. (d) for T > 500 °C, the Na3Fe(SO4)3 compound is replaced by the Na-sulfate thenardite, Na2SO4, plus Fe-oxides, according to the Na3Fe3+(SO4)3 → 3/2 Na2(SO4) + 1/2 Fe2O3 + SOx reaction products. The Na–Fe sulfate disappears around 540 °C. For higher temperatures, the Na-sulfates decomposes and only hematite survives in the final product. The understanding of the thermal behavior of minerals such as sideronatrite and related sulfates is important both from an environmental point of view, due to the presence of these phases in evaporitic deposits, soils and sediments including extraterrestrial occurrences, and from the technological point of view, due to the use of these materials in many industrial applications.

PADOVANI, VERONICA; Buckler, Carlyn S.; GUALTIERI, Alessandro;VESCOGNI, Alessandro ( 2013 ) - To Teach is To Learn: High-School Students, Local University and Informal Science Educators Collaborate in Communicating Science to the Public - EVOLUTION - n. volume 6 - pp. da 7 a 11 ISSN: 1936-6434 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Background: Informal education, especially if in collaboration with formal education, can be an important vehicle for communicating current research in science to the public as well as significant in drawing the young nearer to science and helping them to understand the inherent processes. Methods: In this paper we describe an international collaboration between a group of high-school students in Italy and Earth scientists and museum professionals from Italy and the US to plan and implement a scientific exhibition on symmetry, a topic chosen because of its connections to both Earth science and evolution. Results: By directly involving the high-school students in the design and implementation of the exhibition, they were given ownership of the project as well as ‘hands-on’ experience of communicating science to the public. The students involved helped design the content and layout of the exhibition, as well as with the design and fabrication of exhibition elements, marketing of the exhibition and evaluation. The design allowed the project manager to collect input from the students on how to make exhibitions more ‘user friendly’ to their age demographic, as well as to children and young adults in general. Although more research on similar projects is needed, evaluation results from this project showed that the response of the students - and of visitors - to the exhibition was significantly positive, and suggest that the project was engaging, cost effective and easy to implement. Conclusions: This project may serve as a template for other formal and informal educators to develop these types of collaborations, using informal science education as a bridge to link science researchers and middle- and high-school students in creating an environment where students learn through actively participating in the public communication of science.

Magdalena Lassinantti Gualtieri; Marcello Romagnoli; Paola Miselli; Maria Cannio; Alessandro F. Gualtieri ( 2012 ) - Full quantitative phase analysis of hydrated lime using the Rietveld method - CEMENT AND CONCRETE RESEARCH - n. volume 42(9) - pp. da 1273 a 1279 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Full quantitative phase analysis (FQPA) using X-ray powder diffraction and Rietveld refinements is a well-established method for the characterization of various hydraulic binders such as Portland cement and hydraulic limes. In this paper, the Rietveld method is applied to hydrated lime, a non-hydraulic traditional binder. The potential presence of an amorphous phase in this material is generally ignored. Both synchrotron radiation and a conventional X-ray source were used for data collection. The applicability of the developed control file for the Rietveld refinements was investigated using samples spiked with glass. The results were cross-checked by other independent methods such as thermal and chemical analyses. The sample microstructure was observed by transmission electron microscopy. It was found that the consistency between the different methods was satisfactory, supporting the validity of FQPA for this material. For the samples studied in this work, the amount of amorphous material was in the range 2–15 wt.%.

Alessandro F. Gualtieri; Alberto Viani; Giulia Sgarbi; Gigliola Lusvardi ( 2012 ) - In vitro biodurability of the product of thermal transformation of cement–asbestos - JOURNAL OF HAZARDOUS MATERIALS - n. volume 205-206 - pp. da 63 a 71 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

To safely recycle the product of the thermal transformation of cement–asbestos as secondary raw material,its toxicity potential should be assessed by in vitro biodurability tests. In this work, the acellularin vitro biodurability of the products of transformation of cement–asbestos at 1200 ◦C (named KRY·AS)was tested using both inorganic and organic simulated lung fluids at pH 4.5. The dissolution kineticswere followed using chemical, mineralogical and microstructural analyses. The total dissolution timeestimated from the experiments with inorganic HCl diluted solution is one order of magnitude higherthan that determined from the experiments with buffered Gamble solution (253 days vs. 20 days). Thekey parameter determining the difference in dissolution rate turns out to be the solidus/liquidus ratiowhich prompts a fast saturation of the solution with monosilicic acid. The calculated dissolution rateconstants showed that the biodurability in vitro of KRY·AS is much lower with respect to that of standardchrysotile asbestos (total estimated dissolution time of 20 days vs. 298 days, respectively). This proves alow potential toxicity of this secondary raw material.

GUALTIERI, Alessandro ( 2012 ) - Mineral fibrebased building materials and their health hazards ( - Toxicity of building materials ) (Woodhead Publishing Cambridge (UK) GBR ) - pp. da 166 a 195 ISBN: 0857096354 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

Asbestos minerals have always been considered somehow magic ...

Tobaldi, David M.; Gao, Lian; GUALTIERI, Alessandro; Škapin, Andrijana Sever; Tucci, Antonella; Giacobbe, Carlotta ( 2012 ) - Mineralogical and Optical Characterization of SiO2-, N-, and SiO2/N-Co-Doped Titania Nanopowders - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 95 - pp. da 1709 a 1716 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silica, nitrogen, and nitrogen-plus-silica co-doped titania powders were synthesized via sol–gel method. The products of the synthesis were thermally treated in air and under ammonia flow. The determination of Si and/or N into the TiO2 lattice, and the doped samples' crystal structure, was made by means of X-ray powder diffraction, whilst the occurrence of amorphous phase was obtained using the combined Rietveld-RIR method. The optical properties of the powders were obtained by diffuse reflectance spectroscopy and their energy band gaps were calculated using the differential reflectance method. The photocatalytic activity of the doped samples was assessed in gas phase under UV-light and visible-light irradiation, monitoring the degradation of an organic compound. In addition, the morphology of the samples was further on characterized by means of HRTEM. Nitrogen, silica, and co-doping shifted the anatase-to-rutile (A [RIGHTWARDS ARROW] R) phase transition toward higher temperatures. Silica was found to enter the anatase lattice, and nitrogen was presumed to enter the titania crystal structure as well. Nitrogen doping and SiO2/N-co-doping shifted the light absorption toward the visible region.

GUALTIERI, Alessandro; Veratti, Linda; Tucci, Antonella; Esposito, Leonardo ( 2012 ) - Recycling of the product of thermal inertization of cement-asbestos in geopolymers - CONSTRUCTION AND BUILDING MATERIALS - n. volume 31 - pp. da 47 a 51 ISSN: 0950-0618 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials has become a priority of waste handling in the worldwide environmental agenda. A novel secondary raw material of great importance is the product of the thermal transformation of cement-asbestos, which is chemically comparable to a Mg-rich clinker. Recently, this secondary raw material called KRY•AS has been successfully used for the production of concrete. In this work it has been used for the production of geopolymers. Geopolymers represent a class of synthetic alumino-silicate based materials potentially used in several industrial fields, and in particular in substitution of cements or mortars, with the positive advantage of reducing the emissions of carbon dioxide developed during the clinkering phase. Geopolymers are the result of a reaction of an alumino-silicate, usually metakaolinite, activated with an alkaline silicate solution at room temperature. In the present work, geopolymers obtained from alumino-silicate natural materials mixed with KRY•AS were prepared and characterized. The composition with 2.5 wt.% of KRY•AS presents the best physical and mechanical properties. The presence of KRY•AS introduces about 30 wt.% of amorphous phase in the system. The crystalline component of KRY•AS decomposes in strong basic conditions releasing elements such as calcium and silicon that promote the formation of calcium precipitates and/or minor paracrystalline silicate hydrates. These are responsible for the improved technological performances.

GUALTIERI, Alessandro; PADOVANI, VERONICA editori; autori capitoli: R. Bertolani, A.I. Telloni, A.F. Gualtieri, V. Padovani, F. Catellani Degani, C. Jacoboni, A. Forni, A. Vescogni, A. Chiesi, R. Mattioli, B. Salvarani ( 2012 ) - Symmetria frammenti di armonia universale (Edizioni il Fiorino Modena ITA ) - pp. da 1 a 125 ISBN: 978-88-7549-417-9 ISSN: - [Monografia o trattato scientifico (276) - Monografia/Trattato scientifico]
Abstract

non diponibile

GUALTIERI, Alessandro; Giacobbe, C.; Viti, C. ( 2012 ) - The dehydroxylation of serpentine group minerals - AMERICAN MINERALOGIST - n. volume 97 - pp. da 666 a 680 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal transformation, stability field, and reaction kinetics of serpentine minerals (antigorite, chrysotile, and lizardite) have been studied to draw a comprehensive model for their dehydroxylation and recrystallization reactions. In situ X-ray powder diffraction (XRPD) and kinetic studies were combined with transmission electron microscopy (TEM) observations to describe the mechanisms of dehydroxylation and later high-temperature crystallization. During dehydroxylation, a metastable transition phase with a characteristic peak around 9 Å was observed in antigorite and, to a minor extent, in lizardite. Rietveld refinements confirmed that the 9 Å phase actually possesses a talc-like structure. The appearance of this phase is controlled by structure and kinetic factors. The kinetic parameters and reaction mechanism for lizardite and antigorite dehydroxylation in air at ambient pressure were calculated using the Avrami models and compared to those of chrysotile. For both lizardite and antigorite, the kinetics of dehydroxylation is controlled by diffusion. Apparent activation energy of the reaction in the temperature range 612–708 °C was 221 and 255 kJ/mol for lizardite and antigorite, respectively. The reaction sequences of chrysotile, lizardite, and antigorite leading to the formation of stable high-temperature products (i.e., forsterite and enstatite) are described taking into account previous topotactic and dissolution-recrystallization models.

F. Scordari; G. Ventruti; A.F. Gualtieri; A. Lausi ( 2011 ) - Crystal structure of Na3Fe(SO4)3: a high-temperature product (ca. 400 °C) of sideronatrite [Na3Fe(SO4)2OH•3H2O]. - AMERICAN MINERALOGIST - n. volume 96 - pp. da 1107 a 1111 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The iron sulfate Na3Fe(SO4)3 studied here has been obtained as a high-temperature (HT) product (∼400 °C) from the thermal decomposition of sideronatrite from Sierra Gorda (Chile) having compositionNa2Fe(SO4)2(OH)⋅3H2O. The structure determination was carried out using synchrotron X‑ray powder diffraction. Structural data refined by the Rietveld method, up to Rp = 11.95%, are: space group R3, lattice parameters a = b = 13.6231(1) Å and c = 9.0698(1) Å, V = 1457.76(2) Å3, and Z = 6. The structure of Na3Fe(SO4)3 can be described in terms of FeO6 octahedra connected to sulfate tetrahedra by corner-sharing to form infinite chains [Fe(SO4)3]∞, running along c. These chains are joined together by Na atoms to build up a three-dimensional network of strong (Fe-O-S) and weak (Na-O) bonds. The topological relationships of Na3Fe(SO4)3 to the structure of some analog minerals are also discussed.

M. Lassinantti Gualtieri; M. Romagnoli; A.F. Gualtieri ( 2011 ) - Influence of body composition on the technological properties and mineralogy of stoneware: A DOE and mineralogical–microstructural study - JOURNAL OF THE EUROPEAN CERAMIC SOCIETY - n. volume 31 - pp. da 673 a 685 ISSN: 0955-2219 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper reports a systematic and comprehensive investigation of the effects of the starting mixture composition on the mineralogy and propertiesof porcelain stoneware tiles using mixture design and full quantitative phase analyses by the Rietveld method. Functional relationships betweenproperties and the raw material mixture proportions were obtained and related to the mineralogical composition of the fired product. Mullitecrystallisation depended on the chemical environment. Dissolved quartz mounted to 10 wt% of the dry body regardless on initial amount, indicatingsaturation of the surrounding melt. The paramount role of the amorphous content on the stoneware properties was disclosed quantitatively. Openporosity decreased with increasing amount of amorphous content, and consequently both the stain and wear resistance increased. The CIE-Labcolour parameters a* and b* increased with increased amorphous content due to interaction with surface iron in hematite. The mullite contentincreased wear resistance, thus supporting the mullite strengthening theory.

C. Viti; C. Giacobbe; A.F. Gualtieri ( 2011 ) - Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations. - AMERICAN MINERALOGIST - n. volume 96 - pp. da 1003 a 1011 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

There is increasing concern about the health hazard of asbestos from natural geologic deposits such as greenstones [natural occurring asbestos (NOA)]. Therefore, quantitative determination of the chrysotile asbestos content within massive serpentinites is a recurrent requirement of recent asbestos-inherent law regulations, due to the possible health hazard associated with the release of chrysotile fibers. Unfortunately, the obtainment of accurate and precise quantitative figures of the actual chrysotile content is strongly complicated by typical serpentinite textures, consisting of fine-to-ultrafine intergrowths of fibrous and non-fibrous serpentine minerals, often difficult to identify by conventional methods, such as X-ray diffraction or microanalytical approaches.In this paper, we propose a reliable and straightforward method for the quantitative determination of chrysotile asbestos within bulk massive serpentinites, based on thermal analysis data and, specifically, on the distinctive thermal behavior of chrysotile, lizardite, and antigorite during dehydroxylation at 500–800 °C. Deconvolution processing of DTA endothermic signals in the dehydroxylation temperaturerange revealed good linear correlation between peak area ratios and chrysotile content, for both lizardite + chrysotile and antigorite + chrysotile samples. The DTA correlation curves have been used to determine the chrysotile content in two test serpentinites, revealing surprisingly high-chrysotile content. This novel method is of vast importance as it represents one of the most promising tools for chrysotile quantitative determinations in massive serpentinites, providing unbiased and accurate responses to recent asbestos-related law requirements.

A. F. Gualtieri; M. Boccaletti ( 2011 ) - Recycling of the product of thermal inertization of cement-asbestos for the production of concrete. - CONSTRUCTION AND BUILDING MATERIALS - n. volume 25 - pp. da 3561 a 3569 ISSN: 0950-0618 [Articolo in rivista (262) - Articolo su rivista]
Abstract

A novel field of research in materials science is the recycling of secondary raw materials for constructionand building materials such as concrete. This paper describes the successful recycling of as much as20 wt% of the product of thermal transformation of cement–asbestos for the formulation of concrete.The main mineralogical phases present in the product of transformation of cement–asbestos are C2S, ferrite,and Al-, Ca-, Mg-rich silicates such as akermanite (ideally Ca2MgSi2O7) and merwinite (ideallyCa3Mg2Si2O8). The behavior of this secondary raw material, termed KRYAS, in commercial concretewas investigated using five different mixtures in which various portions (0, 5, 10, 15 and 20 wt%) ofcement were substituted by KRYAS. The results of preliminary technological tests (slump test, compressivestrength, flexural strength after 28 days, and depth of penetration of water under pressure after28 days) were discussed and interpreted with the aid of chemical, mineralogical and SEM analyses.One of the major results is that after 28 days, although all the concrete samples are invariably classifiedas ‘‘ordinary concrete’’ according to the UNI 6132 tests, those diluted with KRYAS display a lower resistanceto compression with respect to the standard. On the other hand, they recover compressive strengthand display values identical to that of the standard after 90 days. The addition of the secondary raw materialhas the effect to slow down the kinetics of setting/hardening because the main cement phase presentin KRYAS is C2S which has a slower rate of hydration with respect to C3S.

Alessandro F. Gualtieri;Carlotta Giacobbe;Lorenza Sardisco;Michele Saraceno;Magdalena Lassinantti Gualtieri; Gigliola Lusvardi;Cinzia Cavenati; Ivano Zanatto ( 2011 ) - Recycling of the product of thermal inertization of cement–asbestosfor various industrial applications - WASTE MANAGEMENT - n. volume 31 - pp. da 91 a 100 ISSN: 0956-053X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials is a priority of waste handling in the countries of the Europeancommunity. A potentially important secondary raw material is the product of the thermal transformationof cement–asbestos, produced by prolonged annealing at 1200–1300C. The product is chemically comparableto a Mg-rich clinker. Previous work has assured the reliability of the transformation process. Thecurrent challenge is to find potential applications as secondary raw material. Recycling of thermally treatedasbestos-containing material (named KRY-AS) in traditional ceramics has already been studied withsuccessful results.The results presented here are the outcome of a long termed project started in 2005 and devoted to therecycling of this secondary raw materials in various industrial applications. KRY-AS can be added in medium-high percentages (10–40 wt%) to commercial mixtures for the production of clay bricks, rock-woolglasses for insulation as well as Ca-based frits and glass–ceramics for the production of ceramic tiles. Thesecondary raw material was also used for the synthesis of two ceramic pigments; a green uvarovite-basedpigment [Ca3Cr2(SiO4)3] and a pink malayaite-based pigment [Ca(Sn,Cr)SiO5]. The latter is especiallyinteresting as a substitute for cadmium-based pigments. This work also shows that KRY-AS can replacestandard fillers in polypropylene plastics without altering the properties of the final product. For eachapplication, a description and relevant results are presented and discussed.

Alessandro Francesco Gualtieri; Giovanni B. Andreozzi; Carlotta Giacobbe;Gigliola Lusvardi;Cecilia Viti ( 2011 ) - Structural and spectroscopic characterization of anorthite synthesized from secondary raw materials - PERIODICO DI MINERALOGIA - n. volume 80,2 - pp. da 231 a 245 ISSN: 0369-8963 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Recycling of secondary raw materials is a priority of waste handling in the countries of theEuropean community. A virtual secondary raw material of great importance is the product ofthe thermal transformation of cement – asbestos. This work illustrates the study of calcinationproducts obtained starting from the product of the thermal transformation of cement-asbestosat 1200 °C, added to primary raw materials (kaolin, aluminum hydroxide) and boric acid asmineralizing agent. The calcination has been conducted at 1200 °C for 1 hour. Thecrystallization kinetics has been monitored using in situ high temperature X-ray powderdiffraction. The microscopic characterization of the final product of calcination has beenconducted with SEM and TEM imaging supported by X-ray microanalysis. The structurerefinement was conducted on the powder sample using the Rietveld method. The results arecompared with the spectroscopic characterization including Mössbauer and UV-Visspectroscopies. The final product of the calcination is essentially anorthite (about 89 wt%)with minor spinel (11 wt%). All experimental data converge to support the hypothesis thatthe anorthite is stoichiometric, and the small amounts of iron detected (1.32 wt%) is Fe3+hosted in the structure of spinel

Federica, Giantomassi; Gualtieri, Alessandro; Lory, Santarelli; Marco, Tomasetti; Lusvardi, Gigliola; Guendalina, Lucarini; Mario, Governa; Armanda, Pugnaloni ( 2010 ) - Biological effects and comparative cytotoxicity of thermal transformed asbestos-containing materials in a human alveolar epithelial cell line - TOXICOLOGY IN VITRO - n. volume 24 - pp. da 1521 a 1531 ISSN: 0887-2333 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Asbestos fibres can be transformed into potentially non-hazardous silicates by high-temperature treatmentvia complete solid-state transformation.A549 cells were exposed to standard concentrations of raw cement asbestos (RCA), chrysotile and cement asbestos subjected to an industrial process at 1200C (Cry_1200 and KRY-AS, respectively),raw commercial grey cement (GC). Cell growth rate and viability (MTT test) were detected in vitro. RCA and KRY-AS subjected to comprehensive microstructural study by electron microscopy were furtherin vitro assayed to compare their cytotoxic potential by morphostructural studies, proliferation index (Ki-67 antigen), apoptosis induction (AO/EB staining) assays and detection of intracellular reactive oxygen species (ROS) with the fluorescent DCFA dye. More severe cytotoxic damage was induced by RCA than by KRY-AS after each incubation period. Exposure to KRY-AS and GC resulted in comparable cell growth rates and cytotoxic effects. Cells incubated with RCA showed greater apoptotic induction and ROS production and a lower cell proliferation index than those exposed to KRY-AS. Chrysotile asbestos and RCA subjected to heat treatment underwent complete microstructure transformation. The final productof heat treatment of cement asbestos, KRY-AS, was considerably more inert and had lower cytotoxic potential than the original asbestos material in all in vitro tests

M. SOLDATI; M. BARBIERI; S. BIOLCHI; F. BULDRINI; S. DEVOTO; E. FORTE; S. FURLANI; A. GUALTIERI; S. LUGLI; M. MANTOVANI; A. MOCNIK; V. PADOVANI; A. PASUTO; D. PIACENTINI; M. PRAMPOLINI; F. REMITTI; J. SCHEMBRI; C. TONELLI; A. VESCOGNI ( 2010 ) - Multidisciplinary geological excursion in the open-air laboratory of the Island of Malta. 11-18 November 2010. Field-Trip Guide. (Dipartimento di Scienze della Terra, Università degli Studi di Modena e Reggio Emilia Modena ITA ) - pp. da 1 a 41 ISBN: 9788890009495 ISSN: - [Monografia o trattato scientifico (276) - Monografia/Trattato scientifico]
Abstract

Si tratta della guida all'escursione geologica multidisciplinare tenutasi a Malta dall'11 al 18 novembre 2010, nell'ambito del progetto di internazionalizzazione dell'Università di Modena e Reggio Emilia dal titolo "Multidisciplinary research in the open-air laboratory of the island of Malta: an internazional network for landslide hazard assessment in coastal areas" (2008-2010) finanziato dalla Fondazione Cassa di Risparmio di Modena e Reggio Emilia, per i Corsi di Laurea Triennale in Scienze Geologiche e Magistrale in Scienze e Tecnologie Geologiche.

A.F. Gualtieri; C. Giacobbe; M. Tonelli; C. Viti ( 2010 ) - Se Plinio avesse un diffrattometro… le trasformazioni ad alta temperatura del serpentino rivelate. - ATTI DELLA SOCIETÀ DEI NATURALISTI E MATEMATICI DI MODENA - n. volume 141 - pp. da 61 a 71 ISSN: 0365-7027 [Articolo in rivista (262) - Articolo su rivista]
Abstract

La famiglia dei minerali del serpentino comprende principalmente il crisotilo (o amianto bianco), la lizardite e l’antigorite. Il più famoso di questi è sicuramente l’amianto bianco che grazie alle sue eccezionali proprietà è noto sin dall’antichità. Plinio il vecchio nel Naturalis Historiae (36, 139 D.C.) ne descrive la capacità di resistere al fuoco. Oggi siamo in grado di comprendere a fondo questa proprietà e definire fino a che punto la struttura molecolare è in grado di resistere al fuoco.In questo lavoro, è stato studiato il campo di stabilità in temperatura dei minerali del serpentino, i relativi prodotti di trasformazione e le cinetiche di reazione dei tre principali polimorfi per una migliore comprensione dei fenomeni petrologici e delle applicazioni in campo industriale ed ambientale.

Alessandro F. Gualtieri; Dario Mangano; Magdalena Lassinantti Gualtieri; Anna Ricchi; Elisabetta Foresti; Giorgio Lesci; Norberto Roveri; Mauro Mariotti; Giovanni Pecchini ( 2009 ) - Ambient monitoring of asbestos in selected Italian living areas - JOURNAL OF ENVIRONMENTAL MANAGEMENT - n. volume 90 - pp. da 3540 a 3552 ISSN: 0301-4797 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper presents the results of an intensive monitoring activity of the particulate, fall-out and soil of selected living areas in Italy with the aim to detect the asbestos concentration in air and subsequent risk of exposure for the population in ambient living environments, and to assess the nature of the other mineral phases composing the particulate matrix. Some areas were sorted out because of the presence of asbestos containing materials on site whereas others were used as blank spots in the attempt to detect the background environmental concentration of asbestos in air. Because the concentration of asbestos in ambient environments is presumably very low, and it is well known that conventional low-medium flow sampling systems with filters of small diameter (25 mm) may collect only a very small fraction of particulate over a short period, for the first time here, an intense monitoring activity was conducted with a high flow sampling system. The high flow system requires the use of large cellulose filters with the advantage that, increasing the amount of collect dust, the probability to collect asbestos fibers increases. Both the protocol of monitoring and analysis are novel and prompted by the need to increase the sensitivity towards the small number of expected fibers. With this goal, the collection of fall-out samples (the particulate falling into a collector filled with distilled water during the monitoring shift) and soil samples was also accomplished. The analytical protocol of the matrix particulate included preliminary X-ray powder diffraction (XRPD), optical microscopy and quantitative electron microscopy (SEM and TEM). Correlations with climatic trends and PM10 concentration data were also attempted.The surprising outcome of this work is that, despite the nature of the investigated site, the amount of dispersed asbestos fibers is very low and invariably lower than the theoretical method detection limits of the SEM and TEM techniques for identification and counting of asbestos fibers. The results are compared to the literature data worldwide and an updated model for asbestos fibers dispersion in ambient environment is proposed.

Lassinantti Gualtieri, Magdalena; Prudenziati, Maria; Gualtieri, Alessandro F ( 2009 ) - Annealing effects on plasma-sprayed Ni: An XRPD study - SURFACE & COATINGS TECHNOLOGY - n. volume 203 - pp. da 345 a 349 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The variation of the size of coherently-diffracting domains and strain due to annealing at moderate temperature (500 °C) has been estimated for plasma-sprayed Ni using X-ray Powder Diffraction (XRPD) and line broadening analysis in conjunction with classical and modified Williamson-Hall methods. It was found that annealing provokes a narrowing of Ni diffraction peaks which was basically associated to a decrease in dislocations present in the as-sprayed material. The evolution of the microstructure with temperature of plasma-sprayed Ni was studied by in situ X-ray Powder Diffraction (XRPD). It was found that the breadth of the Ni profiles continuously decreased with heating up to 500 C, mainly due to healing of dislocations. These results were used to explain the irreversible decrease in electrical resistance of plasma-sprayed Ni resistors after annealing which was previously observed in our laboratory.

Gualtieri A.F. ( 2008 ) - A 15 anni dal bando dell’amianto in Italia. Stato dell’arte e prospettive per una soluzione dell’emergenza - AMBIENTE TERRITORIO - n. volume 2 - pp. da 36 a 41 ISSN: 1971-5455 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Siamo a 15 anni dal bando dell’amianto in Italia. In questo arco di tempo, è continuato costante il numero di decessi per malattie amianto-correlate, sviluppate soprattutto per inalazione di fibre in ambito professionale. Accorciare i tempi di questa lunga scia di morte, eliminando la coda dovuta al contributo di esposizione ambientale, dipende essenzialmente dall’efficacia delle politiche e delle azioni intraprese per fronteggiare l’emergenza. Che speranze ci sono e quali sono le soluzioni concrete per arrivare alla soluzione definitiva del problema amianto in Italia?

M. Lassinantti Gualtieri; M. Prudenziati; A. F. Gualtieri ( 2008 ) - Annealing effects on plasma-sprayed Ni: and XRPD study - SURFACE & COATINGS TECHNOLOGY - n. volume 201 - pp. da 2984 a 2989 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Plasma-sprayed alumina coatings mainly consist of γ-alumina with minor amounts of α-alumina due to incorporation of incompletely fusedpowder. The presence of amorphous materials has also been mentioned in the literature, but not quantified. In this work, X-ray powder diffractionand Rietveld refinements were explored as potential tools for the determination of the amorphous content in plasma sprayed alumina coatings. Tocross-check the accuracy of the Rietveld analysis, standard additions of amorphous alumina were performed. Both approaches provided consistentresults supporting the validity of the Rietveld method for routine quantification of the amorphous phase in plasma-sprayed alumina. For the assprayedcoatings studied in the present work, the amount of amorphous alumina was found to be 12.0±0.7 wt.%.

E. Galli; A.F. Gualtieri ( 2008 ) - Direnzoite, [NaK6MgCa2(Al13Si47O120)•36H2O], a new zeolite from Massif Central (France): Description and crystal structure - AMERICAN MINERALOGIST - n. volume 93 - pp. da 95 a 102 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystal structure of direnzoite, a new natural zeolite found in the cavities of a xenolitic rock from the Massif Central (France) is reported. Apparently, direnzoite was formed throughout a process of hydrothermal crystallization within the vugs of a highly porphyric basalt. The determination of the crystal structure of this new zeolite was at the limits of the existing experimental techniques because of the paucity of available specimen, mainly composed of three tiny aggregates of fibrous microcrystals. The structure of direnzoite, solved by powder methods, was shown to be the K-dominant equivalent of the synthetic zeolite ECR-1 with a framework composed of layers of mordenite (MOR) and mazzite (MAZ) connected in a regular 1:1 stacking sequence with assigned framework topology EON. The chemical composition of direnzoite determined from the structure refinement is (Na0.94K6.62Mg1.42 Ca2.24)(Si,Al)60O120·36.8H2O. The unit cell determined from the Rietveld structure refinement is a = 7.57887(18) Å, b = 18.20098(57) Å, c = 26.15387(83) Å, and the space group is Pmmn.Six extra-framework sites and 14 water molecules were identified within the zeolite micropores. Three extra-framework sites are occupied by K+ ions. The others are occupied by Na+, Ca++, and Mg++. Although direnzoite and ECR-1 share the same framework, the distribution of their extra-framework cations is rather different. In direnzoite, there are no equivalent positions to C1, C2, and C4 positionsfound in ECR-1. Only sites C3 and C3b correspond respectively to K3 and Ca in direnzoite. In direnzoite, K1, K2, and Na correspond to water molecules sites (H2O1, H2O11, and H2O8, respectively)in ECR-1.

Bertacchini M.; Debbi G.; Ferraro G.; Galli E.; Gibertini G.; Gualtieri A.; Iannuccelli V.; Padovani V.; Reginelli M.; Rossi A.; Zinanni M. ( 2008 ) - GEO-benessere: segreti e piaceri. Mostra, Museo Universitario “Gemma 1786”, Dipartimento di Scienze della Terra, 19-20 aprile 2008 [Esposizione (290) - Esposizione]
Abstract

Argille, terme, fanghi e i prodotti che dall'argilla si ricavano per un benessere della persona sia fisico che psichico, hanno animato la mostra realizzata nell'ambito dell'iniziativa "GEO-benessere, approfondimenti e incontri su Geologia, Salute e Wellness", che il Museo Universitario "Gemma 1786" del Dipartimento di Scienze della Terra ha organizzato in occasione della rassegna “Musei da gustare 2008” della Provincia di Modena.Il percorso espositivo è stato realizzato in collaborazione con: Argital (Pozzallo, RG), Smalticeram Unicer (Castellarano, RE), Terme della Salvarola (Sassuolo, MO), Dipartimento di Scienze Farmaceutiche dell’Università di Modena e Reggio Emilia insieme al Gruppo Colorobbia (Sovigliana Vinci, FI).Hanno collaborato alla realizzazione delle visite guidate alla mostra alcuni studenti del Corso di Laurea in Scienze Naturali: Chiara Tonelli; e del Corso di Laurea in Scienze dei beni Culturali: Francesca Amato, Maria Elena Ansaloni, Ambra Mattioli, Eleonora Righi, Laura Rivi, Paola Santisi, Maria Lucia Scarpa.

A. F. Gualtieri; M. Lassinantti Gualtieri; M. Tonelli ( 2008 ) - In situ ESEM study of the thermal decomposition of chrysotile asbestos in view of safe re cycling of the transformation product - JOURNAL OF HAZARDOUS MATERIALS - n. volume 156 - pp. da 260 a 266 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The thermal transformation of asbestos into non-hazardous crystalline phases and their recycling is a promising solution for the “asbestosproblem”. The most common asbestos-containing industrial material produced worldwide is cement-asbestos. Knowledge of the kinetics ofthermal transformation of asbestos fibers in cement-asbestos is of paramount importance for the optimization of the firing process at industrialscale. Here, environmental scanning electron microscopy (ESEM) was used for the first time to follow in situ the thermal transformation ofchrysotile fibers present in cement-asbestos. It was found that the reaction kinetics of thermal transformation of chrysotile was highly slowed downin the presence of water vapor in the experimental chamber with respect to He. This was explained by chemisorbed water on the surface of thefibers which affected the dehydroxylation reaction and consequently the recrystallization into Mg-silicates. In the attempt to investigate alternativeand faster firing routes for the decomposition of asbestos, a low melting glass was mixed with cement-asbestos and studied in situ to assess towhich extent the decomposition of asbestos is favored. It was found that the addition of a low melting glass to cement-asbestos greatly improvedthe decomposition reaction and decreased the transformation temperatures.

R. Arletti; A.F. Gualtieri; F. Di Renzo ( 2008 ) - In situ study of the dehydration of ECR-1: Na-as synthesized and NH4-exchanged in comparison ( 4th International FEZA Conference - Paris (Francia) - 02-06/09/2008) ( - Zeolites and related materials - trends, targets and challenges ) (ELSEVIER Amsterdam NLD ) - n. volume 174b - pp. da 901 a 904 ISBN: 9780444532985 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

The thermal behavior of Na-as synthesized and NH4 exchanged samples of ECR-1 has been studied by synchrotron radiation powder diffraction. The temperature resolved experìments were performed in capillary using a translating imaging piate System. The aim of this study is to follow in sifu thè dehydratìon mechanism of thè zeolite ECR-1, in its as-synthesized and NH4-exchanged forni in order to determine its thermal stability and whether thè structure undergoes phase transition during dehydration. The as-synthesized sample is stable up to 715 °C, whereas the NH4-exchanged one is stable up to 925 °C. Cell parameter refinements show a total volume decrease of 0.95% for thè as-synthesized phase and of 3.82 % for thè NH4 form.

A. F. Gualtieri; L. Veratti; C. Cavenati; I. Zanatto ( 2008 ) - KRY•AS, materia prima secondaria dal processo di trasformazione termica del cemento-amianto: caratteristiche e proposta di riciclo nel grès porcellanato - CERAMICA INFORMAZIONE - n. volume 469 - pp. da 321 a 327 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Il problema amianto nel nostro paese è ancora di preoccupante attualità se si considera che a tutt'oggi in Italia sono presenti più di 2 miliardi di m2 di coperture in cemento amianto che prima o poi andranno bonificate. Grazie al D.M. 29 luglio 2004 n. 248, è possibile intravedere la soluzione definitiva al problema attraverso la trasformazione termica dei rifiuti contenenti amianto ed il successivo riciclo del prodotto di trasformazione. Le nuove normative consentono di industrializzare il processo e di realizzare un impianto di inertizzazione in grado di garantire l’effettiva trasformazione dei materiali contenenti amianto in un composto inerte e riciclabile. E’ possibile affermare che il trattamento termico ed il riciclo dell’amianto trasformato rappresentino oggi una delle frontiere di ricerca applicata più stimolanti. Se guardiamo all'amianto non più come rifiuto, ma come materia prima secondaria (M.P.S.) possiamo affermare che ve ne sia grande disponibilità: solo in regioni come l’Emilia Romagna vengono smaltite circa 9000 ton di cemento-amianto all'anno. Il prodotto della trasformazione, una materia prima secondaria inerte è assolutamente compatibile con l’ambiente e destinato al riutilizzo per diverse possibili applicazioni industriali. In questo contributo verrà descritto il riciclo del prodotto di inertizzazione del cemento-amianto, denominato KRY•AS, in sostituzione di una frazione di materie prime primarie come feldspato sodico e argilla caolinitica per la produzione di piastrelle da grès porcellanato. Lo studio è stato condotto attraverso una completa caratterizzazione chimico-fisica, mineralogica e tecnologica dei materiali di partenza e dei prodotti cotti al fine di valutare l’efficacia della sostituzione dal punto di vista tecnico ed economico.

M. Lassinantti Gualtieri; A. F. Gualtieri; M. Prudenziati ( 2008 ) - Seeded growth of TPA-MFI films using the fluoride methods - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 111 - pp. da 604 a 611 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The fluoride route in combination with surface seeding was used for the preparation of TPA-MFI films on dense amorphous silica glass supports. The use of F− as mineralizing agent allowed the crystallization of TPA-MFI at near-neutral pH (6.7 ± 0.1). The supports were seeded with colloidal TPA-MFI crystals and hydrothermally treated in a synthesis gel at 100 °C for various durations (24–192 h). The synthesis products were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). A film growth rate of about 9 nm/h was found. The crystals in these films exhibit a preferred orientation, with the (1 0 1) planes of the crystals parallel or near parallel to the support surface. Film growth in the near-neutral synthesis gel was also attempted on seeded porous α-alumina supports. However, epitaxial growth of the seed crystals was inhibited by the formation of a uniform layer of colloidal silica particle which covered the seed crystals even in an early stage of hydrothermal treatment. Continuous films could only be prepared by increasing the pH of the initial synthesis mixture from 6.7 to 9.6, thus using both OH− and F− as mineralizing agents. These films are composed of a columnar layer on top of a layer built up of small grains. Such microstructure has previously been reported in the literature for TPA-MFI films grown in conventional synthesis mixtures.

GUALTIERI, Alessandro; S. Ferrari; M. Leoni; G. Grathoff; R. Hugo; M. Shatnawi; G. Paglia; S. Billinge ( 2008 ) - Structural characterization of the clay mineral illite-1M - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 41 - pp. da 402 a 415 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Illite is one of the major clay minerals found on the Earth’s surface, constituent of the soils, and araw material used for a variety of industrial applications. It is an Al-K mica-like, non-expanding,dioctahedral mineral that crystallizes in the monoclinic system. Its structure is very similar to that of2:1 mica, where two tetrahedral sheets sandwich an octahedral one, to build up the T-O-T sheet. Katoms, and possibly water molecules are hosted in the interlayer region.This work presents the results of the structural characterization of illite-1M from Northern Hungarywith the first attempt to refine the structure model and locate the interlayer water molecules. Thestructural characterization was accomplished using current state of the art analytical methodsavailable for the structural characterization of clays. The results illustrate the status of techniquesfor clay structure determination, as well as a structural model for illite.A chemical formula for the illite-1M under investigation can be written as:K0.78Ca0.02Na0.02(Mg0.34Al1.69Fe’’’0.02)[Si3.35Al0.65]O10(OH)2×nH2O.Structure simulations with WILDFIRE yielded a model with 30% of cis-vacant layers andexpandability percentage of 10 %. The value of the percentage of expandability was confirmed withNEWMOD whose best simulation was obtained with 90% of di-octahedral mica, 10% ofexpandable layers, and K = 0.8 in the interlayer region. The best structure simulation obtained withDIFFaX was obtained with a population of the K atoms of 80%. To obtain the best fit, 6 cells alongc (in agreement with the results of the TEM study) and an average dimension of the particles in thea-b plane of 300 nm were used.Besides the determination of the basic structure unit (the results are consistent with those obtainedwith the local information provided by the fit of the PDF data) and the model of disorder, therefinement with DIFFaX+ made it possible attempt to locate the interlayer water molecule and torefine its site population. Although physically sound, both the observed tetrahedral layercorrugation and the location of the water molecule need further experimental support, because thefinal fit of the observed pattern is still imperfect. The reasons for this misfit are thoroughlydiscussed.

A.F. Gualtieri; E. Galli ( 2008 ) - The comparison of the crystal structures of direnzoite, a new zeolite from Massif Central (France), and its synthetic counterpart ECR-1 ( 4° International FEZA Conference - Paris (France) - 02-06/09/2008) ( - Zeolites and related materials - trends, targets and challenges ) (ELSEVIER Amsterdam NLD ) - n. volume 174a - pp. da 499 a 504 ISBN: 9780444532978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

The structures of the natural zeolite direnzoite and its synthetic counterpart ECR-1 were unravelled almost simultaneously using synchrotron powder diffraction. As a matter of fact, the structure refinement of Na-ECR-1 was crucial for the structure solution of direnzoite, which is the lastest discovered natural zeolite. The two structures are distinguished by a 1:1 polysomatic sequence of mordenite (MOR) and mazzite (MAZ) layers. Here, both the crystal structures are discussed and compared in the attempt to disclose their structure directing chemical and kinetic factors.

Gualtieri A.F.; Foresti E.; Lesci I.G.; Roveri N.; Gualtieri Lasinantti M.; Dondi M.; Zapparoli M. ( 2008 ) - The thermal transformation of man made vitreous fibers (MMVF) and safe recycling as secondary raw materials (SRM) - JOURNAL OF HAZARDOUS MATERIALS - n. volume 162 - pp. da 1494 a 1506 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This work describes the high temperature reaction sequence of commercial Man Made Vitreous Fibers(MMVF) Cerafiber, Superwool, Rock wool and Glass wool which may be used as substitute for asbestosin some industrial applications. Knowledge of the reaction path and transformation sequence is veryimportant to assess whether carcinogenic crystalline phases are formed during devitrification, whichmay occur when used as insulators. In addition, knowledge about the nature of the phases formed at hightemperature is mandatory to assess if thermally transformed MMVF can be safely recycled as secondaryraw material (SRM). In this scenario, this study provides useful information for the optimization of theindustrial annealing process aimed to attain a safe, recyclable product.The results of this work show that one of the high-temperature products of Cerafiber and Superwoolis cristobalite which is classified as a carcinogenic. It was possible to define the temperature interval atwhich Cerafiber and Superwool fibers can be safely used as thermal insulators (e.g. insulators in tunneland/or roller kilns, etc.). As cristobalite is formed in both synthetic fiber products at temperatures higherthan 1200 ◦C, their use should be limited to devices operating at lower temperatures.Rock and Glass wool melt upon thermal treatment. As far as the industrial process of inertization isconcerned, a maximum firing temperature of 1100 and 600 ◦C is required to melt Rock wool and Glasswool, respectively, with the high-temperature products that can be safely recycled as SRM. Recycling ofthese products in stoneware tile mixtures were subsequently attempted. The addition of 1–2 wt.% of themelts of Rock and Glasswool gave promising results in terms of viscous sintering reactions and resistanceto staining with the only weak characteristic being the color properties of the fired bodies which tend toworsen.

A. F. Gualtieri; C. Cavenati; I. Zanatto; M. Meloni; G. Elmi; M. Lassinantti Gualtieri ( 2008 ) - The transformation sequence of cement-asbetsos slates up to 1200 °C and safe recycling of the transformation product in stoneware tile mixtures - JOURNAL OF HAZARDOUS MATERIALS - n. volume 152 - pp. da 563 a 570 ISSN: 0304-3894 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cement–asbestos is the main asbestos containing material still found in most of the European countries such as Italy. Man- and weatheringinduceddegradation of the cement–asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern.This concern is the main prompt for the actual policy of abatement and disposal of asbestos containing materials in controlled wastes. An alternativesolution to the disposal in dumping sites is the direct temperature-induced transformation of the cement–asbestos slates into non-hazardous mineralphases. This patented process avoids the stage of mechanical milling of the material before the treatment, which improves the reactivity of thematerials but may be critical for the dispersion of asbestos fibres inworking and life environment. For the first time, this paper reports the descriptionof the reaction path taking place during the firing of cement–asbestos slates up to the complete transformation temperature, 1200 ◦C. The reactionsequence was investigated using different experimental techniques such as optical and electron microscopy, in situ and ex situ quali-quantitativeX-ray powder diffraction. The understanding of the complex reaction path is of basic importance for the optimization of industrial heating processesleading to a safe recycling of the transformed product.For the recycling of asbestos containing materials, the Italian laws require that the product of the crystal chemical transformation of asbestoscontaining materials must be entirely asbestos-free, and should not contain more than 0.1 wt% fraction of the carcinogenic substances such ascristobalite. Moreover, if fibrous phases other than asbestos (with length to diameter ratio >3) are found, they must have a geometrical diameterlarger than 3m. We have demonstrated that using an interplay of different experimental techniques, it is possible to safely verify the completetransformation of asbestos minerals in this temperature-induced process.The product of transformation of cement–asbestos (CATP) has a phase composition similar to that of a natural or a low temperature clinker withthe exception of having a larger content of aluminium, iron and magnesium. This product can be safely recycled for the production of stonewaretile mixtures. The addition of 3–5 mass% of CATP does not bear significant variations to the standard parameters of white porcelain tile mixtures.

Gualtieri A.F. ( 2008 ) - Una soluzione tecnologica definitiva al problema amianto in italia - AMBIENTE TERRITORIO - n. volume 5 - pp. da 32 a 37 ISSN: 1971-5455 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Questo lavoro fa seguito all’articolo dal titolo A 15 anni dalbando dell’amianto in Italia. Stato dell’arte e prospettive peruna soluzione dell’emergenza apparso sul numero di aprile.L’articolo in questione presenta un quadro globale delproblema amianto e accenna alle possibilità esistenti perarrivare alla soluzione definitiva dell’emergenza in Italia. Inquesto contributo viene descritta in dettaglio una soluzionetecnologica denominata KRY•AS, alternativa all’interramentoin discarica, per la trasformazione totale dei rifiuticontenenti amianto e l’eventuale riutilizzo del prodotto ditrasformazione come materia prima seconda.

M. LASSINANTTI GUALTIERI; C. ANDERSSON; F. JAREMAN; J. HEDLUND; A. GUALTIERI; M. LEONI; C. MENEGHINI ( 2007 ) - Crack formation in a-alumina supported MFI zeolite membranes studied by in situ high temperature synchrotron powder diffraction (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - JOURNAL OF MEMBRANE SCIENCE - n. volume 290 - pp. da 95 a 104 ISSN: 0376-7388 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Cracks are frequently formed in α-alumina supported MFI membranes during calcination. To better understand crack formation, in situ powder diffraction data were collected during calcination of a type of MFI membrane (ca. 1800 nm thick) which is known to crack reproducibly. In addition, data for MFI powder and a blank support were also collected. Both a synchrotron radiation facility and an in-house instrument were used. The unit cell parameters were determined with the Rietveld method, and the strain in the direction perpendicular to the film surface was calculated for the film as well as for the support. The microstrain in the support was also estimated. Based on the results obtained here, a model for crack formation in this type of MFI membrane was proposed. The lack of cracks in other types of MFI membranes (ca. 500 nm) prepared in our laboratory is also explained by the model. In thicker MFI films, the crystals are well intergrown. During heating, the MFI crystals contract and the α-alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks in the film and structural defects in the support. In thinner films, the crystals are less well intergrown and the thermal expansion mismatch leads to opening of grain boundaries rather than cracks.

C. Colella; A.F. Gualtieri ( 2007 ) - Cronstedt’s zeolite - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 105 - pp. da 213 a 221 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Axel F. Cronstedt (1722-1765), famous Swedish mineralogist, was the first scientist to describe,250 years ago, the distinctive property of zeolites, i.e., the unique frothing characteristics whenheated in a blow-pipe flame. Cronstedt examined two specimens: one from Svappavaara inNorthern Sweden and one that was said to come generically from Iceland. From Cronstedt’sindications, the occurrence of the first specimen was near the mining area of Kiruna. Themorphological characteristics of the specimen suggested the zeolite species is stilbite which wouldmake it the first discovered zeolite mineral.This paper is devoted to the description of the structure and microstructure of that first discoverednatural zeolite from Svappavaara (Northern Sweden). The SEM investigation of all the sample rockcavities filled with the zeolite crystals and the optical observation of the separated zeolite crystalsrevealed that the sample is mainly composed of stellerite with subordinate stilbite crystals which arepresent only in a few cavities together with stellerite. The chemical formula of the stellerite crystalsderived from the EPMA and TG analyses is (Ca4.03Mg0.01Na0.03K0.11)[Si27.81Al8.19O72]×28.6H2O. Theresults of the structure refinement confirm that the investigated specimen is actually stellerite. Thestructure refinement evidenced no ordering in the tetrahedral sites. The extraframework cation Ca islocated in the centre of the main channel parallel to the a axis, on the mirror plane and issurrounded by water molecules with no contact with framework oxygen atoms. The coordination ofCa is 6-fold. A number of short water-water distances are possible by considering the differentpossible schemes around the Ca atom. Considering the short water-water distances and the partialoccupancy of water sites, a number of octahedral coordination around Ca are possible.

G. Malavasi;G. Lusvardi;A. Pedone;M.C.Menziani;M.Dappiaggi; A. Gualtieri; L. Menabue ( 2007 ) - Crystallization Kinetics of Bioactive Glasses in the ZnO-Na2O-CaO-SiO2 System - JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY - n. volume 111(34) - pp. da 8401 a 8408 ISSN: 1089-5639 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The crystallization kinetics of Na2OâCaOâ2SiO2 (x ) 0) and 0.68ZnOâNa2OâCaOâ2SiO2 (x ) 0.68, where xis the ZnO stoichiometric coefficient in the glass formula) bioactive glasses have been studied using bothnonisothermal and isothermal methods. The results obtained from isothermal XRPD analyses have showedthat the first glass crystallizes into the isochemical Na2CaSi2O6 phase, whereas the Na2ZnSiO4 crystallinephase is obtained from the Zn-rich glass, in addition to Na2CaSi2O6. The activation energy (Ea) for thecrystallization of the Na2OâCaOâ2SiO2 glass is 193 ( 10 and 203 ( 5 kJ/mol from the isothermal in situXRPD and nonisothermal DSC experiments, respectively. The Avrami exponent n determined from theisothermal method is 1 at low temperature (530 °C), and its value increases linearly with temperature increaseup to 2 at 607 °C. For the crystallization of Na2CaSi2O6 from the Zn-containing glass, higher values of boththe crystallization temperature (667 and 661 °C) and Ea (223 ( 10 and 211 ( 5 kJ/mol) have been foundfrom the isothermal and nonisothermal methods, respectively. The Na2ZnSiO4 crystalline phase crystallizesat lower temperature with respect to Na2CaSi2O6, and the Ea value is 266 ( 20 and 245 ( 15 kJ/mol fromthe isothermal and nonisothermal methods, respectively. The results of this work show that the addition ofZn favors the crystallization from the glass at lower temperature with respect to the Zn-free glass. In fact, itcauses an increase of Ea for the Na diffusion process, determined using MD simulations, and consequentlyan overall increase of Ea for the crystallization process of Na2CaSi2O6. Our results show good agreementbetween the Ea and n values obtained with the two different methods and confirm the reliability of thenonisothermal method applied to kinetic crystallization of glassy systems. This study allows the determinationof the temperature stability field of the crystalline phases with the view of creating a different glass ceramicuseful in the field of bioactive materials.

A. F. Gualtieri; D. Mangano; G. Torri; A. Ricchi; E. Foresti; G. Lesci; N. Roveri; M. Mariotti; G. Pecchini ( 2007 ) - Il monitoraggio outdoor del particolato atmosferico, con particolare attenzione all’amianto. Studio di ambienti di vita nelle Province di Bologna, Modena e Reggio Emilia - GIORNALE DEGLI IGIENISTI INDUSTRIALI - n. volume 32(4) - pp. da 277 a 304 ISSN: 1122-1666 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In questo lavoro vengono riportati i principali risultati di un progetto di ricerca a lungo termine, finanziato dalla Fondazione Cassa di Risparmio di Modena, per lo studio delle fasi aerodisperse, con particolare riferimento alle fasi dell’amianto, in ambienti outdoor di vita nelle Province di Bologna, Modena e Reggio Emilia. Il monitoraggio dell’aerodisperso è stato possibile grazie ad un campionatore ad alto flusso messo a disposizione dall’A.R.P.A. di Reggio Emilia. Oltre al particolato atmosferico, per ogni stagione sono stati raccolti campioni di terreno e campioni di fall out. I siti studiati hanno natura diversa ed alcuni, come quelli industriali con coperture di cemento-amianto, possono rappresentare una minaccia per la salute dei lavoratori che abitualmente operano in prossimità della copertura.In un clima di crescente allarmismo nei confronti del problema amianto in Italia e di generale confusione nella letteratura esistente riguardo la concentrazione atmosferica di amianto, questo lavoro contribuisce a definire il reale livello di rischio di esposizione ad amianto per la cittadinanza negli ambienti di vita esterni.Inoltre, mancando riferimenti normativi sui limiti di concentrazione di fibre aerodisperse in ambiente outdoor di vita, questo contributo può essere di aiuto per definire la concentrazione ambientale media (livello di fondo) e cercare di fissarne il limite.

MAGDALENA LASSINANTTI GUALTIERI; M. PRUDENZIATI; ALESSANDRO F. GUALTIERI ( 2007 ) - Quantitative determination of the Amorphous Content in Plasma Sprayed Alumina Coatings using the Rietveld method (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - SURFACE & COATINGS TECHNOLOGY - n. volume 201 - pp. da 2984 a 2989 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Plasma-sprayed Al2O3 coatings mainly consist of gamma-Al2O3 with minor amountts of alpha-Al2O3 due to incorporation of incompletely fused powder. The presence of amorphous materials was also mentioned in the literature, but not quantified. In this work, x-ray powder diffraction and Rietveld refinements were explored as potential tools for the determination of the amorphous content in plasma sprayed Al2O3 coatings. To cross-check the accuracy of the Rietveld analysis, stardard additions of amorphous Al2O3 were performed. Both approaches provided consistent results supporting the validity of the Rietveld method for routine quantification of the amorphous phase in plasma-sprayed Al2O3. For the as-sprayed coatings studied in the present work, the amount of amorphous Al2O3 was found to be 12.0 % +-0.7 wt.%.

A.F. Gualtieri ( 2007 ) - Thermal behavior of the raw materials forming porcelain stoneware mixtures by combined optical and in situ X-Ray dilatometry - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 90(4) - pp. da 1222 a 1231 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The dilatometric behavior of the raw materials forming a porcelainstoneware tile mixture was investigated at a molecular/microscopical scale by combined in situ optical dilatometry andX-ray powder diffraction. Each single raw material was investigatedseparately and mixed with all the others to simulate astandard production mixture. Thus, it was possible to evaluatewhether the reaction path taking place during the firing of theraw materials is changed during the firing of the combined mixture.A general classification of the causes of contraction and/orexpansion events has been attempted. Causes are subdivided intostructural (S, intra-mineral) and microstructural (M, inter-mineral).Contractions can be generated by: loss of volatiles (S);structure collapse of the pseudo-amorphous products of dehydroxylationof clay minerals (S); solid state or viscous sintering(M); crystallization from amorphous precursor (S) and relatedvolume reduction (densification) (M); displacive phase transitionwith a volume decrease (S); and melting generally at T48001C(S). Expansion can be generated by thermal expansion (S);displacive phase transition with a volume increase (S); glasstransitions (S) and related volume change (M); and overfiring/pyroplastic deformation (M). Many reactions observed in thesingle raw materials have also been observed in the mixture. Themajor variations concern (i) crystallization of cristobalite is observedonly in the kaolin and not in the mixture, where silicasegregated from the reaction of formation of mullite from metakaoliniteis readily incorporated in the alkaline amorphousphase; (ii) quartz alone is stable with temperature but tends tobe partly decomposed in contact with the alkaline melt in themixture; and (iii) in the illite-rich clay, melting of the system andsubsequent expansion caused by pyroplastic deformation of theK-rich melt begins at relatively low temperature (11501C). Thisbehavior is not observed in the mixture below 13501C where apresumably less viscous melt is formed.

G. Torri; A.F. Gualtieri ( 2007 ) - Utilizzo di cemento-amianto inertizzato termicamente per la produzione di lana di vetro e roccia - RIVISTA DELLA STAZIONE SPERIMENTALE DEL VETRO - n. volume 4 - pp. da 17 a 24 ISSN: 0391-4259 [Articolo in rivista (262) - Articolo su rivista]
Abstract

All’interno di un progetto più ampio, in questolavoro abbiamo verificato con successo la possibilitàdi riciclare il prodotto di inertizzazione delcemento-amianto all’interno delle miscele impiegateper la produzione di materiali isolanti comelana di vetro e lana di roccia. Oltre al prodotto inertizzato,nella formulazione delle lane è statoaggiunto un feldspato di basso costo dall’Isolad’Elba ed argille rosse dell’AppenninoSettentrionale e della Sardegna.

G. PECCHINI; A. GUALTIERI; E. RENNA; O. SALA; L. CALZAVACCA; T. BACCHI; F. PAOLI; V. BIANCOLINI ( 2006 ) - Analytical evaluation of wastes containing asbestos after inertization treatment by pirolitic process ( European Conference on Asbestos Risks and management - Roma - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (ISPESL Roma ITA ) - n. volume - - pp. da 183 a 186 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Wastes recovery efficiency bave been slightly improved by Decree n.248 of 29/7/2004 on" Rules on determination and disciplines of recovery activities of products and goods of asbestos and containing asbestos" by defining processes and treatment able to bring to a complete transformation of crystallochemical features of asbestos.Such treatments if properly applied allows to avoid thè disposai of wastes in dumps. They also allow thè reutilizalion of processed wastes. No adequate power plants suitable for thè mentioned treatment presently exist in Italy.Intense research activity is devoted to thè start up of pyrolitic processes applied to wastes deriving from concrete/asbestos to be reutilized in environmental recovery. Decree n.248 reports characteristics of processed material whìch must be asbestos free and accompanied by mineralogical composition of final produci.Present paper propose an analytical protocol suitable for law need and able to guarantee safety conditions of wastes after crystallochemical transformation.In order to verìfy such trans formations analytical procedures adopted in qualifìed laboratories on asbestos analysis nave been utilized. Pure chrysotile and concrete/asbestos samples have been analyzed by MOCF, DRX, SEM and FTIR after 2 hours heating at 600-700-800-900-1000 °C in muffle fornace. Some samples processed by pilot power plani by Aspireco have also been analyzed.

D. MANGANO; A. GUALTIERI; S. FERRARI; A. RICCHI; E. FORESTI; G. LESCI; N. ROVERI; M. MARIOTTI; G. PECCHINI ( 2006 ) - Asbestos monitoring in civil and industrial environments of selected Italian sites ( Conference on Asbestos Risks and management - Roma - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (ISPESL Roma ITA ) - n. volume - - pp. da 140 a 145 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This paper presents the results of an intensive monitoring activity of thè air, fall-out and soil of a Ceramic factory in Sassuolo (Modena, Italy) with sheds made of cement-asbestos. The monitoring protocol accomplished a 1 week long collection time performed during each season. Filters and samples of fall-out and soils were analysed with XRPD, electron and optical microscopy, and FTIR. The surprising outcome of this work is that the calculated amount of dispersed asbestos fibers is practically null with a minor concentration during thè autumn season.

A. GUALTIERI; S. FERRARI ( 2006 ) - Kinetics of illite dehydroxylation - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 33 - pp. da 490 a 501 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Illite is a dioctahedral K-deficient mica with an interlayer cation content of 0.6-0.85 atoms per formula unit. 1M and 2M(1) are the illite polytypes more abundant in nature. Because illite is one of the major component of clays used for the production of traditional ceramics, the understanding of its high temperature transformations is of paramount importance for the knowledge of the structural and microstructural properties of fired ceramic products. To our knowledge, the study of the illite dehydroxylation kinetics has not been attempted to date. Hence, this work presents the investigation of the reaction mechanism of dehydroxylation of illite for the first time. The natural sample investigated in this study is a 1M-polytype from Hungary. Several classical methods of kinetic analysis were used (isoconversional method, Avrami method, direct fit with kinetic expressions, and others) to achieve a complete picture of the dehydroxylation mechanism. The proposed model for the dehydroxylation of illite is a multi-step reaction sequence with (1) condensation of the water molecule in the octahedral layer; (2) one-dimensional diffusion of the water molecules through the tetrahedral ring (rate limiting step of the reaction); (3) two-dimensional diffusion of the water molecules through the interlayer region (rate limiting step of the reaction).

M.Romagnoli; T.Bellarmi; A.F.Gualtieri; C.Bes; S.Celestini; A.Sevagen ( 2006 ) - Metodi di studio ed ottimizzazione utili nel processo ceramico. La previsione del ritiro ceramico ed applicazioni in campo industriale - CERAMICA INFORMAZIONE - n. volume 454 - pp. da 605 a 609 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

E' stata mostrata la possibilità di raggiungere rapidamente l'ottimizzazione di formulazioni d'impasti con evidenti vantaggi economici e qualitativi. I metodi proposti sono quelli della regressione lineare a più variabili e dell'approccio neurale. Entrambe consentono di ottenere un modello matematico col quale simulare virtualmente il comportamento del sistema in diverse condizioni. Quest'ultimo viene ottenuto utilizzando i dati storici presenti in azienda oppure da dati sperimentali. Nell'intervento è stata mostrato un esempio applicato agli impasti: ì modelli sono stati costruiti sui dati di ritiro in relazione alla composizione, espressa comepercentuale delle singole materie prime, e alla temperatura massima di cottura. I modelli sono stati testati con venti formulazioni di prova mostrando una ottima capacità predittiva. La disponibilità di softwares in grado dì eseguire i calcoli necessari e la ridotta richiesta di conoscenze matematiche rende le due metodologie di facile e rapida introduzione in ambito industriale.Based on the linear regression with variables and artificial neural network, a math. model was developed enabling the simulation of the system behavior under different conditions. Existing historical data or through test results were employed in obtaining the model. As an example, the capability of the model to predict the shrinkage in processing of ceramic materials, i.e. between the dried state and after heat treatment cycles, was shown, the compn. expressed as raw materials percentage, and max. firing temp. being taken into account. The models were tested with twenty different formulas and showed excellent predictive capacity. The availability of software packages that could perform all necessary calcns. and the little math. knowledge enabled the easy and rapid introduction of the developed model in industrial processes.

M. LASSINANTTI GUALTIERI; M. PRUDENZIATI; A. GUALTIERI ( 2006 ) - Quantitative determination of the amorphous phase in plasma sprayed alumina coatings using the Rietveld method (Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598 ) - SURFACE & COATINGS TECHNOLOGY - n. volume 201 - pp. da 2984 a 2989 ISSN: 0257-8972 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Plasma-sprayed alumina coatings mainly consist of γ-alumina with minor amounts of α-alumina due to incorporation of incompletely fused powder. The presence of amorphous materials has also been mentioned in the literature, but not quantified. In this work, X-ray powder diffraction and Rietveld refinements were explored as potential tools for the determination of the amorphous content in plasma sprayed alumina coatings. To cross-check the accuracy of the Rietveld analysis, standard additions of amorphous alumina were performed. Both approaches provided consistent results supporting the validity of the Rietveld method for routine quantification of the amorphous phase in plasma-sprayed alumina. For the as-sprayed coatings studied in the present work, the amount of amorphous alumina was found to be 12.0 ± 0.7 wt.%.

A. GUALTIERI; A. VIANI; C. MONTANARI ( 2006 ) - Quantitative phase analysis of hydraulic limes using the Rietveld method - CEMENT AND CONCRETE RESEARCH - n. volume 36 - pp. da 401 a 406 ISSN: 0008-8846 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Quantitative phase analyses of three commercial samples of hydraulic limes have been per-formed using the Rietveld method. Although the Rietveld method has been already applied to cement analysis, we report here the first application to different classes of hydraulic binders, such as hydraulic limes (HL) and natural hydraulic limes (NHL). Unlike HL, that are simple diluted cement, NHL are specific product of great interest for its application in building restoration and conservation. Samples were also characterized by laser granulometry and chemical analysis. Thermogravimetric analysis/Differential Scanning Calorimetry (TG/DSC) and calcimetric analyses were conducted to compare the results of such well-established techniques with those obtained with the Rietveld method. Taking advantage of the Rietveld method with the addition of an internal standard, the phase fraction of all the crystalline phases as well as the amorphous component, have been accurately determined. This technique offers a valid support for the characterization of hydraulic limes in the light of the EN classification of such industrial products.

AF Gualtieri; E. Passaglia ( 2006 ) - Rietveld structure refinement of NH4-exchanged natural chabazite - EUROPEAN JOURNAL OF MINERALOGY - n. volume 18 - pp. da 351 a 359 ISSN: 0935-1221 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work the results of the X-ray Rietveld structure refinement of a natural and the corresponding NH4-exchanged chabazite from Nova Scotia (Canada) are exposed. Experimental data were collected using a laboratory powder diffractometer equipped with copper tube and graphite crystal monochromator. The outcome of this crystal-structure study is useful for (i) understanding the structure modifications induced by the NH4+ exchange: (ii) understanding the physical-chemical and technological properties of NH4-chabazite, a zeolite vastly used for industrial applications, (iii) understanding the mechanism of proton conductivity of the NH4-exchanged zeolites, precursors of catalytically active H+ forms. The position and orientation of the NH4+ ion were initially refined using the rigid body model and later with the aid of soft constraints. The coordination number of the ammonium ion is 9 with two equally possible and mutually exclusive configurations. One coordination environment includes 3 oxygen atoms O3, 3 oxygen atoms O4, and 3 H2O molecules W2a. The other environment includes 3 oxygen atoms O3. 3 oxygen atoms O4, and 3 H2O molecules W3. As already shown for other NH4-zeolites, the N-O distances are larger than the N-H2O distances. The local geometry of the ammonium ion points to a monodentate configuration. A bidentate configuration of the hydrogen bonds for NH4+ is also possible if the long H2(center dot center dot center dot)O3 separation is considered to be at bond distance. For industrial and technological applications, knowledge of the local environment of NH4+ in the cavities of zeolites is important. Weak hydrogen bonds with framework oxygen atoms implies that the ammonium molecule can be easily exchanged or desorbed. This property is attractive for agronomy, horticulture and soil remediation where zeolite can be added to chemical fertilizers to improve the soil's chemical and physical properties for plant growth, to increase fertilizer efficiency and to reduce the leaching of nutrients, to reduce the dissolution rate of a soluble fertilizer via ion exchange or combination of mineral dissolution and ion exchange, and to act as remediation agents in soils.

A. GUALTIERI; S. FERRARI; E. GALLI; F. DI RENZO; W. VAN BEEK ( 2006 ) - Rietveld structure refinement of zeolite ECR-1 - CHEMISTRY OF MATERIALS - n. volume 18 - pp. da 76 a 84 ISSN: 0897-4756 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In this work, we present the structure refinement of ECR-1 to give the first direct evidence of the proposed structure of this synthetic zeolite. In fact, a model of the structure of ECR-1 was proposed on the basis of high-resolution transmission electron microscopy (HRTEM) evidence and the structure solution of the synthetic gallo-silicate TNU-7, but it has not been refined to date. The proposed model consists of structure layers of mordenite (MOR) and mazzite (MAZ) connected in a regular 1: 1 stacking sequence and framework topology EON. Because single crystals of ECR-1 cannot be synthesized, the structure was refined using the Rietveld method. High-resolution synchrotron powder diffraction data were collected on both the synthetic Na-ECR-1 and NH4-ECR-1 samples at ESRF. Na atoms located on the axis of the eight-member ring channels in mordenite and zeolite omega are not present in Na-ECR-1. In Na-ECR-1, the equivalent sites lay near the walls of the eight-membered-ring channels. This difference is presumably at the basis of the formation of ECR-1 because, during growth, the local symmetry deformation of the eight-membered-ring channel prevents the formation of the MOR or MAZ structures and justify the periodical shift from one structure to the other. A quantitative explanation of the anisotropic peak broadening observed in the powder patterns is also given.

M. LASSINANTTI GUALTIERI; A. GUALTIERI; J. HEDLUND ( 2006 ) - The influence of heating rate on template removal in silicalite-1: An in situ HT-XRPD study (Elsevier Science Incorporated / NY Journals:Madison Square Station, PO Box 882:New York, NY 10159:(212)633-3730, EMAIL: usinfo-f@elsevier.com, INTERNET: http://www.elsevier.com, Fax: (212)633-3680 ) - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 89 - pp. da 1 a 8 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The effect of heating rate on thermal behavior of TPA-silicalite-1 during calcination and the reaction kinetics for TPA decomposition were investigated. The cell parameters of the TPA-silicalite-1 during the heating cycles were determined with the aid of high temperature X-ray diffraction data and the Rietveld method. The template decomposition is accompanied by a large contraction of the unit cell. The unit cell dimensions during template removal are not affected significantly by the heating rate. Consequently, the rate of contraction is approximately proportional to the heating rate. The intensity of some diffraction peaks changes during heating, especially the 101/011 and the 200/020 peaks. The intensity change of those peaks shows the same dependence with temperature as the TPA occupancy, indicating that these parameters are related. An analysis of the kinetics for TPA decomposition based on the intensity change of the 101/011 and the 200/020 peaks was performed. The apparent activation energy (Ea) of the template decomposition in silicalite-1 determined with the Kissinger and the Flynn–Wall–Ozawa methods was 138 (±25) and 138 (±29) kJ mol−1, respectively. The reaction order, determined with the method of Kennedy and Clark, was close to 0.5 indicating that the rate-limiting step is mono-dimensional diffusion. Ea was 140 (±30) kJ mol−1, in good agreement with the results obtained with the other methods.

A.F. Gualtieri; P. Aprea ( 2006 ) - The structure of K-hydrosodalite - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 96 - pp. da 276 a 286 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Hydrosodalite, Na-6[AlSiO4](6)center dot 8H(2)O, is a synthetic modification of natural sodalite with water molecules replacing for the anion at the centre of the beta cage. Hydrosodalite has a cubic structure with space group P (4) over bar 3n and a approximate to 8.9 angstrom. Cation ordering and framework distortions leading to symmetry reduction were observed for synthetic sodalites but have never been reported for hydrosodalite. This work reports the first experimental evidence of a symmetry reduction in hydrosodalite. The investigated sample is a K-exchanged hydrosodalite with chemical formula K-6[AlSiO4](6)center dot 7.8H(2)O. The structure refinement was performed using synchrotron powder diffraction data in space group P1 with a = 9.196(1) angstrom, b = 9.188(1) angstrom, and c = 9.205(1) angstrom, alpha = 89.69(1)degrees, beta = 90.43(1)degrees, and gamma = 89.791(9)degrees. K+ strongly interacts with all the framework oxygen atoms of the hexagonal ring and provokes anisotropic distortion of the framework. In the distorted framework, the only possible distribution scheme for the K+ ions is ordered, to prevent any Coulomb repulsion between adjacent ions. In addition, the ordered scheme is the only to ensure even distribution of the positive cation charges with respect to the Al atoms (AI:K ratio is 1: 1). In fact, each of the six Al atoms has three K+ ions at a distance of 3.5-3.9 angstrom and in turn, each of the six K+ ions has three Al atoms at a distance of 3.5-3.9 angstrom. K+ ions display a coordination number from 8 to 10 and mean K-O distance, including the water molecules, of 2.921-3.043 angstrom. (c) 2006 Elsevier Inc. All rights reserved.

S. FERRARI; A. GUALTIERI ( 2006 ) - The use of illitic clay in the production of stoneware tile ceramics - APPLIED CLAY SCIENCE - n. volume 32 - pp. da 73 a 81 ISSN: 0169-1317 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Illite is one of the main clay phases used for the preparation of mixtures for traditional ceramics. The raw materials used for production of white porcelain stoneware tiles mainly consist of feldspars, quartz, and clay minerals (kaolinite, smectite and illite). In this study, eight clayey raw materials with a different content of illite up to 70 wt.%, have been considered. The crystalline phases present in different amounts are illite, smectite, kaolinite, illite-smectite mixed-layers, K-feldspar, plagioclases, quartz, and accessory phases (anatase, goethite). The clays have been chemically and physically characterized as raw and fired materials with X-ray diffraction, X-ray fluorescence, and SEM. Moreover they were added in the percentage of 35 wt.% to a mixture composed of albite, feldspar sand and quartz sand, to reproduce that commonly used for the production of porcelain stoneware tiles. We focused on the quantitative mineralogical aspects of the unfired and fired bodies and their relationship with the technological properties due to the presence of illite. Increasing illite content yields higher percentage of glass phase and lower water absorption because of the lowering of the melting point. Because of the pyroplastic deformation, linear shrinkage decreases with illite content. The presence of illite inhibits the formation of mullite and cristobalite, since silica and alumina tend to form alkaline glass. Although in clays from Hungary, transition elements are present in very low percentage, the colour of the fired bodies is darker. These clays contain goethite, which may be rapidly oxidized with temperature, and show a very low percentage of newly formed mullite which could eventually host Fe in its structure.

A. GUALTIERI; G. ELMI ( 2006 ) - Understanding the high temperature reaction sequence during the thermal treatment of cement-asbestos slates ( European Conference on Asbestos Risks and management - Roma - 4-6 dicembre 2006) ( - Proceedings European Conference on Asbestos Risks and management ) (Pubblicazione ISPESL ROMA ITA ) - n. volume - - pp. da 187 a 192 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This paper reports the description of the reaction path taking place during the firing of cement-asbestos slates followed using different experimental techniques (optical microscopy, SEM, TEM , quali- quantitative X-Ray powder diffraction, FTIR). It will be demonstrated that only an interplay of different experimental techniques (mainly diffraction end electron microscopy) can lead to a safe verification of the yield of thermal transformation of asbestos minerals. The understanding of the complex temperature induced reaction path is of paramount importance for the optimization of industrial heating processes to yield a safe transformed product to be eventually recycled.

G. PECCHINI; A. GUALTIERI; E. RENNA; O. SALA; L. CALZAVACCA; T. BACCI; F. PAOLI; V. BIANCOLINI ( 2006 ) - Valutazione analitica del rifiuto di cemento amianto dopo trattamento di inertizzazione con processo pirolitico (Assn Italiana Igienisti Indust(AIDII):via GB Morgagni 32, 20129 Milan Italy:011 39 02 20240956, EMAIL: aidii.consul@flashnet.it, Fax: 011 39 02 20241784 ) - GIORNALE DEGLI IGIENISTI INDUSTRIALI - n. volume 31 - pp. da 98 a 107 ISSN: 1122-1666 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In questo studio è stata fatta la valutazione analitica del rifiuto di cemento amianto dopo trattamento di inertizzazione con processo pirolitico. Sono stati valutati gli effetti sia sull'amianto di serpentino che quello di anfibolo. Le tecniche utilizzate sono state XRPD, FTIR e SEM.

S. FERRARI; E. ORI; A. GUALTIERI; A. TUCCI; A. CSEBI; J. BIBER ( 2005 ) - Possibilità di impiego dell’illite di Füzérradvány (Ungheria) in impasti da grès porcellanato (Gruppo Editoriale Faenza Editrice:via Pier de Crescenzi 44, I 48018 Faenza Italy:011 39 0546 670111, EMAIL: info@faenza.com, Fax: 011 39 0546 660440 ) - CERAMICA INFORMAZIONE - n. volume 444 - pp. da 524 a 531 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Con il termine illite si intende un i di alluminio e potassio simile alle miche, che non espande, diottraedrìco e che si ritrova nella frazione argillosa. Insieme alla caolinite, alla clorite e alla smectite è uno dei 4 maggiori costituenti delle rocce argillose. L'illite è una fase in parte ancora sconosciuta a causa della difficile reperibilità come minerale puro; spesso è associata a smectite, dalla quale è impossìbile separarla.In questo lavoro viene presentato un giacimento illite situatonell'Ungheria Nord-orientale, vicino al paese di Fuzérradvany, non ancora descrìtto nella letteratura mineralogica intenazionale. La regione dell'Ungheria Nord-orientale ai confini con la Slovacchia, appartiene al complesso monfuoso dei Monti Tokaj, ed in quanto tale è costituita da rocce acide dì origine vulcanica. La formazione di questo importante giacimento è dovuta all'alterazione da parte di fluidi idrotermali, che hanno interessato rocce riolitiche.La miniera dì Fuzérradvany è in grado di produrre 4 diverse qualità dì argilla illitica: EXTRA, A, B e C. ln questo studio sono state prese in esame le due qualità con un maggiore contenuto di illite: EXTRA ed A. Le due argille sono state caratterizzate dal punto di vista chimico-fisico. Inoltre, è stato studiato ìl comportamento in temperatura. Alle variazioni osservate nelcomportamento dilatometrico è stato dato un significato in termini mineralogici e microstrutturali, potendo seguire le trasformazioni con diffrazione a Raggi X in situ e microscopia elettronica a scansione.Questo lavoro si inquadra in un progetto generale ai studio i argille illitiche nel campo dei ceramici tradizionali, che prende in esame argille con un diverso contenuto di illite dal 5 ai 70%; ottenendo importanti ìnformazioni su come l'impasto stesso modifichi le sue caratteristiche quando il minerale viene inserito in percentuali diverse. Dai confronti dì tutti i dati ottenuti ci si propone infatti dì valutare gli effetti della presenza di illite in impasto e come la variazione delle sue percentuali possa modificare le proprietà del prodotto finito, in modo tale da ottimizzare le condizioni di uso di questa importante nuova materia prima ceramica.

FERRARI S.; GALLI E.; GUALTIERI A.F. ( 2005 ) - Preliminary characterization of an unknown mineral from Mont Peylenc (Massif Central, France) ( - OXIDE BASED MATERIALS - New sources, novel phases, new application ) (ELSEVIER AMSTERDAM NLD ) - n. volume 155 - pp. da 261 a 269 ISBN: 9780444519757 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The discovery of a new natural zeolite phase is a rare event since only less than one hundred natural zeolites are known to date. We have been recently involved in a research project aimed at the investigation of a microscopic aggergate coming from the Massif Central (France) that appears to be anew zeolite species. The sample was collected more than 30 years ago by Professors Glauco Gottardi and Ermanno galli and since then, many unsuccesful attempts have been made to disclose the crystal chemistry of this new3 species. The quantity of available material is very limited, and single crystals are not available. For this reason, structure determination from powder diffraction data is attempted. This work represents the result of preliminary chemical, microscopy and minralogical charcterization of this apparently unknown mineral, mainly using X-ray podwer diffraction. All data point to a new zeolite species and the results will be hopefully integrated in the future with the crystal strcture solution by the powder methods.

PASSAGLIA, Elio; S. Poppi; P. Azzolini; GUALTIERI, Alessandro ( 2005 ) - Reduction of the Na content of irrigation waters using chabazite-rich tuff ( 3rd Conference of the Federation-of-European-Zeolite-Association - Prague, CZECH REPUBLIC - AUG 23-29, 2005) ( - MOLECULAR SIEVES: FROM BASIC RESEARCH TO INDUSTRIAL APPLICATIONS, PTS A AND B ) - n. volume 158 - pp. da 2097 a 2104 ISBN: 0-444-52082-1 ISSN: 0167-2991 [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Lab experiments showed that the Italian chabasite-rich tuff from Sorano (Grosseto) is able to remove Na from low quality irrigation waters, harmful for agriculture, and turn them into high quality waters. The treatment is obtained via a three steps process: water percolation through natural zeolitite bed, regeneration of the exhausted zeolitite with NH4 or with K, and water percolation through the regenerated zeolitite. The quantity of treated water is inversely proportional to the content of Na of the original water. The efficiency of the zeolitite is slightly improved after regeneration. The process was successfully applied to a large-scale in two horticultural farms which Supplied the irrigation waters utilized for the lab tests.

L. ESPOSITO; E. RAMBALDI; A. TUCCI; E. GAETTI; A. GUALTIERI ( 2005 ) - Riciclo di amianto inertizzato termicamente in impasti da grès porcellanato. ( Ecomondo 05 - Rimini - 26-29/10/2005) ( - Ecomondo 05 ) (MAGGIOLI Bologna ITA ) - n. volume - - pp. da 768 a 774 ISBN: 978 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Nella presente ricerca si è valutata la possibilità di riciclare amianto inertizzato termicamente con torcia al plasma, in impasti da grès porcellanato. Il materiale inertizzato, denominato INERTAM, è costituito per circa 50% da una fase amorfa. Il restante 50% è costituito da fasi cristalline fra le quali prevale la gehlenite-akermanite (ca. 36% del totale). Considerando il carattere refrattario dell'INERTAM, si è ritenuto opportuno sostituirlo ai materiali, quali le sabbie, che negli impasti ceramici svolgono una funzione smagrante e strutturale. Partendo da un impasto da grès porcellanato commerciale, scelto come riferimento, è stato preparato un nuovo impasto, sostituendo il 2.5% di sabbia feldspatica con l'1%di INERTAM.Il nuovo impasto ha messo in evidenza caratteristiche migliori rispetto al materiale standard, presentando a 1220°C, valori di assorbimento d'acqua inferiori, 0,82%, e un ritiro lineare di 7,9%. Le analisi al microscopio elettronico a scansione (SEM), dei provini sinterizzati, hanno evidenziato una microstruttura più omogenea e meno porosa rispetto a quella dell'impasto standard.

G. VENTRUTI; F. SCORDARI; E. SCHINGARO; A. GUALTIERI; C. MENEGHINI ( 2005 ) - The order-disorder character of FeOHSO4 obtained from the thermal decomposition of metahohmannite, Fe2(3+H2O)4[O(SO4)(2)] - AMERICAN MINERALOGIST - n. volume 90 - pp. da 679 a 686 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

The iron sulfate FeOHSO4 studied was obtained as a dehydration product of metahohmannite Fe-2(H2O)(4)[O(SO4)(2)] during a synchrotron real-time powder diffraction experiment. As quoted in the literature, FeOHSO4 has iron atoms octahedrally coordinated with two hydroxyl groups and four sulfate O atoms, while each hydroxyl group is bonded to two iron atoms. This compound is commonly described in the orthorhombic system with space group Pnma, lattice parameters a(J) = 7.33, b(J) = 6.42, and c(J) = 7.14 angstrom (a(J), b(J), and c(J) are the Johansson lattice parameters), and Z = 4. However a preliminary Rietveld refinement of the pattern at about 220 degrees C using the structural model from the literature yielded a poor fit of the observed data and a final R-p value of about 23%. A careful analysis of the calculated powder diffraction pattern showed unexpected peaks, not observed in the experimental trace, for h = 2n + 1, while sharp reflections for h = 2n seemed to point to different lattice constants and space group. The recognition of the order-disorder character of the FeOHSO4 compound was the key to successfully interpreting the unexpected features of the experimental powder pattern and the misfit with respect to the calculated pattern. In fact, FeOHSO4 belongs to a family of OD structures formed by equivalent layers of symmetry Pbmm. Only two MDO (Maximum Degree of Order) polytypes are possible. MDO1 results from a regular alternation of stacking operators 2(1/2) and 2(-1/2), and yields an orthorhombic structure with space group Prima and lattice parameters a(J) = 7.33, b(J) = 6.42, and c(J) = 7.14 angstrom. MDO2 results from the 2(1/2)/2(1/2)/2(1/2)... sequence of symmetry operators and yields a monoclinic structure with space group P2(1)/c, a(M) = 7.33, b(M) = 7.14, c(M) = 7.39 angstrom, and = 119.7 degrees. The analysis of one-dimensional stacking disorder was performed by fitting the observed XRPD pattern with a calculated intensity curve generated by DIFFaX. The disorder model was investigated by taking into account a probability matrix for the occurrence of OD layer sequences. The best fit (R-P = 0.009) to the observed powder pattern was obtained with a 61:39 ratio of monoclinic and orthorhombic polytypes for a fully disordered OD layers sequence.

Lassinantti Gualtieri M.; Gualtieri A.F.; Hedlund J.; Jareman F.; Sterte J.; Dapiaggi M. ( 2004 ) - Accurate measurement of the thermal expansion of MFI zeolite membranes by in situ HTXRPD ( 14th International Zeolite Conference - Cape Town (South Africa) - 25-30/04/2004) ( - 14th International Zeolite Conference ) (Document Transformations Technologies Cape Town ZAF ) - n. volume - - pp. da 703 a 709 ISBN: 9780958466363 ISSN: - [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

Template removal by calcination of MFI type membranes is often accompanied by crack formatìon. The thermal behavior of MFI type membranes, synthesized with and without masking, was studied to understand the mechanìsm. Masking prevents growth of zeolite in thè interior of the support during membrane synthesis. Rietveld refìnements of powder diffraction data collected in situ at high temperature allowed to accurately determine the change in thermal expansion of thè MFI film and thè porous a-alumìna support. During heating, a relatively large contraction of the celi volume during template removal occurred in thè zeolite powder and in thè film of thè membrane prepared with masking. The much smaller decrease in thè non-masked sample indicates that this membrane is under stress during heating and as a consequence, cracks are formed. The stress imposed in the membrane prepared without masking may be due to the opposite thermal behavior of the substrate in combination with strong bonds between thè membrane and thè support.

M. MARIANI; P. PIZZOLI; R. SANTINI; P. CALICETI; S. FERRARI; A. GUALTIERI ( 2004 ) - Argille illitiche: composizione, struttura, microstruttura e comportamento negli impasti ceramici da grès porcellanato (Gruppo Editoriale Faenza Editrice:via Pier de Crescenzi 44, I 48018 Faenza Italy:011 39 0546 670111, EMAIL: info@faenza.com, Fax: 011 39 0546 660440 ) - CERAMICA INFORMAZIONE - n. volume 436 - pp. da 664 a 670 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

La relazione vuole raccogliere lo stato dei lavori che stiamo portando avanti nel nostro laboratorio riguardo alla ricerca e l'indagine sulle materie da impasto. Abbiamo posto l'attenzione sulla plasticità delle argille e sulle interconnessioni, alcune note e altre un po' meno, tra le caratteristiche tecniche di lavorabilità e le composizioni chimiche e mìneralogiche di questi materiali. Abbiamo preso in considerazione 7 argille diverse, utilizzate attualmente in impasti ceramici nazionali e non, aventi tenori di allumina dal 20 al 28%. Questo lavoro presenta la fase preliminare di un progetto più vasto in cui si intende raccogliere un numero molto più consistente di dati e creare un data base significativo in termini statistici.

M.PRUDENZIATI; B. MORTEN; A. F. GUALTIERI; M. LEONI ( 2004 ) - Dissolution Kinetectcs and diffusivity of silver in glassy layers for hybrid microelectronics (Kluwer Academic Publishers:Journals Department, PO Box 322, 3300 AH Dordrecht Netherlands:011 31 78 6576050, EMAIL: frontoffice@wkap.nl, kluweronline@wkap.nl, INTERNET: http://www.kluwerlaw.com, Fax: 011 31 78 6576254 ) - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS - n. volume 15 - pp. da 447 a 453 ISSN: 0957-4522 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silver and palladium/silver compositions are widely used in hybrid microelectronics, as electrodes for dielectric layers and multilayers, terminations of thick film resistors and interconnections. Interactions between Ag and the adjacent films are known to affect the microcircuit performances. The present study is aimed at collecting data on the behavior of Ag-based films in contact with glassy layers. Most experiments were performed with a glass with composition 68.2 PbO : 30.5 SiO2 : 1.3 Al2O3 wt %. Two different systems were analyzed. The first system consists of thick films prepared from a paste containing glass and either 3 or 15 wt % silver particles; both fine (spherical grains, 0.5–1 mgrm diameter) and coarse (flakes, 2–5 mgrm, <1 mgrm thick) Ag powders were used for these pastes. The distribution of Ag in the film was studied with X-ray diffraction, scanning electron microscopy and fluorescence analysis. The results show that Ag floats on the glassy layer. Diffraction of X-rays generated by a synchrotron radiation source allowed us to study the kinetics of silver dissolution in the glass; this phenomenon is consistent with the Avrami theory, with an apparent activation energy E dis=0.69±0.04 eV. The second system analyzed, Ag-based terminations of glass layers fired at various peak temperatures, enabled us to obtain quantitative values for both Ag solid solubility (about 2.5 wt %) and Ag diffusion coefficients D Ag(T ). Typical values of D Ag(850 °C) are 30.3±11.9 10–8 cm2/s; an apparent activation energy of the diffusion process is E a=0.6±0.1 eV.

M. Prudenziati; B. Morten; A.F. Gualtieri; M. Leoni ( 2004 ) - Dissolution kinetics and diffusivity of silver in glassy layers for hybrid microelectronics - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS - n. volume 15 - pp. da 447 a 453 ISSN: 0957-4522 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Silver and palladium/silver compositions are widely used in hybrid microelectronics, as electrodes for dielectric layers and multilayers, terminations of thick film resistors and interconnections. Interactions between Ag and the adjacent films are known to affect the microcircuit performances. The present study is aimed at collecting data on the behavior of Ag-based films in contact with glassy layers. Most experiments were performed with a glass with composition 68.2 PbO:30.5 SiO2:1.3 Al2O3 wt%. Two different systems were analyzed. The first system consists of thick films prepared from a paste containing glass and either 3 or 15 wt% silver particles; both fine (spherical grains, 0.5-1 mum diameter) and coarse (flakes, 2-5 mum, < 1 μm thick) Ag powders were used for these pastes. The distribution of Ag in the film was studied with X-ray diffraction, scanning electron microscopy and fluorescence analysis. The results show that Ag floats on the glassy layer. Diffraction of X-rays generated by a synchrotron radiation source allowed us to study the kinetics of silver dissolution in the glass; this phenomenon is consistent with the Avrami theory, with an apparent activation energy E-dis = 0.69 +/- 0.04 eV. The second system analyzed, Ag-based terminations of glass layers fired at various peak temperatures, enabled us to obtain quantitative values for both Ag solid solubility (about 2.5 wt%) and Ag diffusion coefficients D-Ag(T). Typical values of D-Ag(850&DEG;C) are 30.3 +/- 11.9 10(-8) cm(2)/S; an apparent activation energy of the diffusion process is E-a = 0.6 +/- 0.1 eV.

GUALTIERI, Alessandro; D. Levy; E. Belluso; M. Dapiaggi ( 2004 ) - Kinetics of the decomposition of crocidolite asbestos: A preliminary real-time X-ray powder diffraction study ( 8th European Powder Diffraction Conference - Uppsala, SWEDEN - MAY 23-26, 2002) ( - EUROPEAN POWDER DIFFRACTION EPDIC 8 ) - n. volume 443-4 - pp. da 291 a 294 ISBN: 0-87849-935-0 ISSN: 1662-9752 [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This work is a preliminary kinetic study of the crocidolite decomposition followed in situ at high temperature using real time conventional powder diffraction and DTA in the temperature range 720-795 degreesC. The data analysis using the Avrami models indicates that the rate limiting step of the reaction is monodimensional ion diffusion (n=0.5) with an activation energy of 129 (10) kcal/mole.

Reginelli M.; Settembre D.; Bertoni A.; Rovini A.; Vezzalini G.; Gualtieri A.; Carpenito G. ( 2004 ) - Ottimizzazione di impasti da monoporosa - CERAMICA INFORMAZIONE - n. volume 438 - pp. da 855 a 868 ISSN: 0009-0271 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In questo studio sono state analizzate le proprietà tecnologiche di impasti da gres smaltato con composizioni chìmiche molto diverse, indagando quanto il chimismo e la mineralogia possano influenzare il coefficiente di dilatazione del prodotto finito. Attraverso le analisi condotte è stato possibile ipotizzare un rapporto ottimale SiO2/Al2O3 e Na2O/K2O rispetto ai parametri più critici del processo produttivo: macinazione, smaltatura e cottura. Questi dati, rappresentano la prima fase di un progetto di ricerca più ampio, nel corso del quale si dovranno studiare gli effetti della macinazione, della natura e delia quantità della fase vetrosa, sul coefficiente di dilatazione, fornendo un contributo, al confronto in corso sul tema, sia alle aziende, che agli enti dì ricerca istituzionaii.

Gualtieri AF; Brignoli G ( 2004 ) - Rapid and accurate quantitative phase analysis using a fast detector - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 37 - pp. da 8 a 13 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The accuracy of the weight fractions calculated with the Rietveld method for various polycrystalline systems using data collected for very short times (545 min) with an RTMS (real-time multiple strip) detector was verified. The weight estimates were compared with those obtained using the same conventional Bragg-Brentano geometry, a gas proportional detector and a 13 h data acquisition. The analysed samples were monophasic and polyphasic mixtures with different degrees of complexity: the standard corundum NIST 676; a sample (labelled 1g) provided as a standard sample for the IUCr CPD Quantitative Phase Analysis Round Robin; a natural pyroclastic rock from Riano (Rome, Italy) containing zeolitic minerals and a glass phase; and a hydraulic lime. The results of the refinements show estimated weights consistent with both those obtained with a gas proportional detector and with the nominal values, indicating a very good accuracy. Only when variable slits are used, the accuracy of the estimated weights slightly decreases. The outcome of this work is a very important step forward towards fast and accurate QPA for production control and quality management, obtained by combining the use of a rapid detector and existing user-friendly software.

M. LEONI; GUALTIERI, Alessandro; N. ROVERI ( 2004 ) - Simultaneous refinement of structure and microstructure of layered materials - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 37 - pp. da 166 a 173 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The recursive description of stacking in layered crystals, originally developed by Treacy et al. [Proc. R. Soc. London Ser. A (1991), 433, 499-520] and implemented in the DIFFaX code, is enclosed in a non-linear least-squares minimization routine and combined with additional models (of specimen-related broadening and instrumental broadening) to allow the simultaneous refinement of both structural and microstructural parameters of a layered crystal. This implementation is named DIFFaX+. As examples, the refinements both of a simulated pattern of diamond, showing fault clustering, and of the observed powder pattern of a synthetic stoichiometric nanocrystalline chrysotile are reported.

Gualtieri AF; Norby P; Grey CP; Hanson JC ( 2004 ) - Sorbate rearrangement and cation migration in HFC-134 loaded NaY zeolite: A temperature dependent synchrotron powder diffraction study ( 8th European Powder Diffraction Conference - Uppsala, SWEDEN - MAY 23-26, 2002) ( - EUROPEAN POWDER DIFFRACTION EPDIC 8 ) - n. volume 443-444 - pp. da 295 a 298 ISSN: 0255-5476 [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

The HFC-134/NaY binding has been monitored by temperature dependent X-ray powder diffraction. Diffraction patterns were obtained as a function of different loading levels to investigate the rearrangement of the cations and of the HFC-134 molecules, in the temperature range 100-230 K. In situ real-time data were collected using a Translating Imaging Plate System (TIPS) at the NSLS (USA). Rietveld structure refinements were performed for the HFC-134 (32 molecules per unit cell [m/uc = molecules per unit cell] or 4 molecules per supercage [m/sc = molecules per supercage]) using data collected from 100 to 230 K. A phase transition is observed at about 180 K (A to B phase transition) where a disordering of the HFC-134 molecule takes place and modification of its surrounding due to Na+ migrations is observed. These results are preliminary and the experiment with the 32 m/ue should be repeated in order to assess whether the observed effect is reproducible.

Perchiazzi N; Gualtieri AF; Merlino S; Kampf AR ( 2004 ) - The atomic structure of bakerite and its relationship to datolite - AMERICAN MINERALOGIST - n. volume 89 - pp. da 767 a 776 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Four samples of bakerite, Ca4B5Si3O15(OH)(5), were studied by means of IR, TG/DSC, EPMA, and X-ray and neutron diffraction. Chemical analyses can readily discriminate bakerite from datolite, Ca4B4Si4O16(OH)(4), by the distinctly lower SiO2 content of the former. The Rietveld refinement of the combined neutron and X-ray powder data allow the determination of the crystal structure of bakerite to R-p 3.09%. The crystal structure can be derived from that of datolite by the substitution 0.25Si(4+) + 0.25O(2-) <----> 0.25B(3+) + 0.25(OH)(-) at the Si-centered tetrahedral site. This leads to the crystal chemical formula Ca(4)B(5)Si(3)0O(15)(OH)(5). Both of the two hydrogen positions in the bakerite structure, one with full occupancy, the other with 25% occupancy, were precisely located. The water molecule generally thought to be present in bakerite structure is actually absent. The excess water detected in chemical analyses can be attributed to the presence of minor impurities. Given the consistent composition of bakerite from various localities and no evidence for Substitution of B for Si in datolite, bakerite is retained as a distinct species. A possible explanation of the peculiar 5:3 boron to silicon ratio in bakerite is provided.

Gualtieri A.F.; Guagliardi A.; Iseppi A. ( 2004 ) - The quantitative determination of the crystalline and amorphous content by the Rietveld method: application to glass ceramics with different absorption coefficients ( - Diffraction analysis of the microstructure of materials ) (Springer Berlin DEU ) - n. volume 68 - pp. da 147 a 165 ISBN: 9783540405191 ISSN: - [Contributo in volume (Capitolo o Saggio) (268) - Capitolo/Saggio]
Abstract

The Rietveld method provides an accurate determination of the crystalline and the amorphous fractions in polyphase mixtures. To determine the content of the amorphous phase, the sample is diluted with an internal standard which is considered as a component itself and refined with the other phases. Although the method is accurate for systems containing crystalline and amorphous phases with an absorption coefficient comparable to that of the standard, it was not thoroughly tested for systems containing a weakly or highly absorbing amorphous phase. Commonly, this is the case for glass ceramics which may contain elements with fairly different atomic number.X-ray powder diffraction data refined with the Rietveld method were utilized for the determination of the amorphous content in a number of systems containing glasses with different absorption coefficients (Li-, B-, Al-, P-, Zn-, Zr-, Ba-, Pb-glass) to check the accuracy of the method. The mixtures were prepared diluting the glass phase with corundum NIST 676 and hydroxyapatite NIST 2910 in fixed proportions. The refinements were carried out with GSAS and the new code QUANTO, especially developed for automatic quantitative phase analysis (QPA) of polycrystalline mixtures eventually including an amorphous component.The glass weights estimated by the two programs are both in good agreement with the nominal value (45 wt%) although a minor dependency of the calculated amorphous fraction on the linear absorption coefficient of the glass was observed and attributed to microabsorption effects. The Brindley (1945) correction applied here according to the formulation of Taylor and Matulis (1991) revealed not to be fully satisfactory for mixture containing an amorphous component with a very different absorption coefficient, especially when highly accurate determinations are required. This is in concert with the general concern that the existing models for the correction of microabsorption effects should be revised as they are not adequate even for systems containing only crystalline phases (Madsen et al., 2001).The method was successfully applied to a commercial glass ceramic indicating that it can be applied with a good accuracy also to glass ceramics with fairly different absorption coefficients.

Scordari F; Ventruti G; Gualtieri AF ( 2004 ) - The structure of metahohmannite, Fe-2(3+)[O(SO4)(2)]center dot 4H(2)O, by in situ synchrotron powder diffraction - AMERICAN MINERALOGIST - n. volume 89 - pp. da 365 a 370 ISSN: 0003-004X [Articolo in rivista (262) - Articolo su rivista]
Abstract

Metahohmannite, Fe-2(3+)[O(SO4)(2)].4H(2)O, is a hydrated sulfate of ferric iron that occurs in sulfate deposits in the desert areas of Northern Chile. The compound used for this study was obtained as a dehydration product of hohmannite, Fe-2(3+)[O(SO4)(2)].(4+4)H2O. Intensities for the structure analysis were collected from a powdered sample using in situ synchrotron X-ray powder diffraction at ESRF (Grenoble, France). The structure was solved ab initio by profile deconvolution and the application of standard Patterson and difference Fourier maps. The structure was refined to R-p = 5.46% using the Rietveld method. Metahohmannite crystallizes in the triclinic system, space group P (1) over bar with unit-cell parameters a = 7.3484(5) Angstrom, b = 9.7710(6) Angstrom, c = 7.1521(5) Angstrom, alpha = 91.684(5)degrees, beta = 98.523 (5), gamma = 86.390(5)degrees, and Z = 2. The structure consists of four Fe3+ octahedra and four sulfate tetrahedra, which share vertices and edges to form a complex building block of Fe-4(3+)[O-2(SO4)(4)].8H(2)O composition. Such blocks are connected to form chains running parallel to the c axis. A complicated system of hydrogen bonds connects adjacent chains into a three-dimensional network. Finally, the crystal structures of metahohmannite, hohmannite, and amarantite are compared and the geometrical features discussed in detail.

L. ESPOSITO; A. SALEM; A. TUCCI; A. GUALTIERI; S.H. JAZAYERI ( 2004 ) - The use of nepheline-syenite in a body mix for porcelain stoneware tiles (Elsevier Applied Science:An Imprint of Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington Oxford OX5 1GB United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: nlinfo-f@elsevier.nl OR usinfo-f@elsevier.com OR forinfo-kyf04035@niftyserve.or.jp, INTERNET: http://www.elsevier.nl/, Fax: 011 44 1865 843010 ) - CERAMICS INTERNATIONAL - n. volume 31 - pp. da 233 a 240 ISSN: 0272-8842 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In the study, the possibility to use nepheline-syenite, as fluxing agent, in a body mix used for porcelain stoneware tile, was determined. Starting from the reference mix composition, different amounts, 5.0, 10.0 and 15.6 wt.%, of sodium feldspar were replaced with the same amounts of nepheline-syenite. Different sintering cycles were used to understand the role of the nepheline-syenite in the development of the final microstructure. The presence of nepheline-syenite strongly favours the sintering behaviour, by reducing the sintering time necessary to reach the water absorption values, requested by the International Standard. Furthermore, the microstructure results more homogeneous and the mechanical characteristics are increased. The better mechanical performances can also be attributed to the different mineralogical compositions, in particular with lower amount of glassy phase, higher flexural strength values are obtained.

G Falini; E Foresti; M Gazzano; AF Gualtieri; M Leoni; IG Lesci; N. Roveri ( 2004 ) - Tubular-shaped stoichiometric chrysotile nanocrystals - CHEMISTRY-A EUROPEAN JOURNAL - n. volume 10 - pp. da 3043 a 3049 ISSN: 0947-6539 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Stoichiometric chrysotile tubular nanocrystals have been synthesized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular interactions between chrysotile, the most utilized asbestos, and biological systems. Chrysotile nanocrystals have been synthesized under controlled hydrothermal conditions, and have been characterized by chemical, morphological, structural, spectroscopic and microcalorimetric analyses. They show a constant cylinder-in-cylinder morphology constituted by two or three concentric subunits. Each single nanocrystal has a tubular shape of about 49 +/- 1 nm in outer maximum diameter, and a hollow core of about 7 +/- 1 nm. Structural investigation carried out on an Xray powder pattern allowed to improve the structural model proposed for chrysotile mineral samples. Synthetic chrysotile crystallizes in the monoclinic Cc space group with a= 0.5340(l) nm, b = 0.9241(l) nm, and c = 1.4689(2) nm, beta = 93.66(3)degrees.

S. Ferrari; A.F. Gualtieri; T. Bellarmi; C. Pasquali ( 2004 ) - Utilizzo del talco in impasti da grès porcellanato superbianchi: caratteristiche mineralogiche, chimiche e microstrutturali - C+CA - n. volume XXXIV - pp. da 69 a 84 ISSN: 1970-0393 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Lo scopo di questo studio sul talco è quello di valutare il suo impiego negli impasti da grés porcellanato superbianco. Lo studio è stato svolto utilizzando tecniche di laboratorio di carattere tecnologico e tecniche analitiche quali XRD, XRF, SEM per la caratterizzazione mineralogica, chimica e microstrutturale dei materiali naturali e edei cotti. Con questo lavoro, ci si propone quindi di indicare quale sia la materia prima contenente talco più idonea per gli impasti da grés porcellanato superbianchi e di ottimizzarne la quantità da aggiungere all'impasto stesso.

A., Cattaneo; Gualtieri, Alessandro; G., Artioli ( 2003 ) - Kinetic study of the dehydroxylation of chrysotile asbestos with temperature by in situ XRPD - PHYSICS AND CHEMISTRY OF MINERALS - n. volume 30 - pp. da 177 a 183 ISSN: 0342-1791 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The kinetics of the dehydroxylation of chrysotile was followed in situ at high temperature using real-time conventional and synchrotron powder diffraction (XRPD). This is the first time kinetics parameters have been calculated for the dehydroxylation of chrysotile. The value of the order of the reaction mechanism calculated using the Avrami model indicates that the rate-limiting step of the reaction is a one-dimensional diffusion with an instantaneous nucleation or a deceleratory rate of nucleation of the reaction product. Hence, the rate-limiting step is the one-dimensional diffusion of the water molecules formed in the interlayer region by direct condensation of two hydrogen atoms and an oxygen atom. The calculated apparent activation energy of the reaction in the temperature range 620-750 degreesC is 184 kJ mol(-1). The diffusion path is along the axis of the fibrils forming the fibers. The amorphous or short-range ordered dehydroxylate of chrysotile is extremely unstable because forsterite readily nucleates in the Mg-rich regions. Moreover, it is less stable than the dehydroxylate of kaolinite, the so-called metakaolinite, which forms mullite at about 950 degreesC. This difference is interpreted in terms of the different nature of the two ions Mg2+ and Al3+ and their function as glass modifier and glass-forming ion, respectively.

M. Prudenziati; F. Zanardi; B. Morten; A.F. Gualtieri ( 2002 ) - Lead-free thick film resistors: an explorative investigation - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS - n. volume 13 - pp. da 31 a 37 ISSN: 0957-4522 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Pastes prepared with seven lead-free glass particles were screen-printed and fired on 96\%-Al2O3 substrates. The fired films were studied in terms of sintering, devitrification, crack propagation and bleeding. The most promising glass compositions were selected for the preparation of RuO2-based thick film resistors (TFRs), on pre-fired PtAu- or PdAg-based terminations; electrical properties of the resistors (sheet resistance vs. RuO2 volume fraction, temperature coefficient of resistance and size effects) were investigated. The study evidenced a myriad of complex phenomena, including devitrification, relevant bleeding of the glass on alumina substrates, anomalous distribution of conductive grains in the glassy matrix, phase separations. Contrarily to what happens in traditional systems, it is difficult to get a wide resistance range simply by changing the fraction of the conductive phase. These results emphasize the criticality in the choice of the glass composition for the preparation of lead-free thick film resistors.

A., Viani; Gualtieri, Alessandro; Gorgoni, Carlo; P., Pallante; G., Cruciani ( 2001 ) - Characterization of Mg-calcites from marbles of the Mediterranean area - NEUES JAHRBUCH FUR MINERALOGIE MONATSHEFTE - n. volume 7 - pp. da 311 a 325 ISSN: 0028-3649 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Mg-rich calcites from marbles of the Mediterranean area were accurately characterized by Rietveld X-ray powder diffraction (XRPD) and X-ray fluorescence (XRF) for the determination of the Mg content of the samples. The data set seems to be highly consistent, despite the different metamorphic environment under which calcite grains have formed. Results indicate that previously reported determinative curves, regarding synthetic Mg-calcites, relating the c/a ratio to the Mg content of the carbonate, do not hold for these natural inorganic samples which display an ideal, or nearly ideal, behaviour of the calcite - dolomite solid solution for compositions between 0 and 4 % mole MgCO3.

M. PRUDENZIATI; B.MORTEN; B.FORTI; A.F.GUALTIERI; G.MIHAI DILLIWAY ( 2001 ) - Devitrification kinetics of high lead glass for hybrid microelectronics - INTERNATIONAL JOURNAL OF INORGANIC MATERIALS - n. volume 3 (7) - pp. da 667 a 674 ISSN: 1466-6049 [Articolo in rivista (262) - Articolo su rivista]
Abstract

In order to elucidate crystallization phenomena in high lead glasses for hybrid microelectronics, we studied the devitrification in screen printed and annealed films made with borosilicate glass particles with the composition PbO-SiO2-B(2)iO(3) = 65:25:10 % wt. Formation of SiO2 polymorphs, beta -cristobalite and quartz, was observed in films printed on alumina (Al2O3) or beryllia (BeO) and fired in the temperature range from 700 to 1000 degreesC. X-ray diffraction of samples annealed in isothermal conditions enabled the collection of data for studying the kinetics of formation and dissolution of the crystalline phases. The crystallization of beta -cristobalite on both substrates is governed by an Avrami model. At lower temperatures, the reaction order coefficient indicates an interface controlled reaction with an instantaneous or deceleratory nucleation rate and 3D growth. The apparent activation energy of the crystallization process is independent of the substrate being 15(1) kcal/mol and 14.7(9) kcal/mol for samples on Al2O3 and BeO substrates, respectively, whereas the decomposition reaction is favored on alumina, with E-d = 30(2) kcal/mol in this case, but 55(3) kcal/mol for beryllia substrates. (C) 2001 Elsevier Science Ltd. All rights reserved.

M.PRUDENZIATI; F.ZANARDI; B. MORTEN; A.F.GUALTIERI ( 2000 ) - Lead free glasses for new generation of thick-film resistors: an explorative investigation ( International Symposium on Microelectronics and Packaging, - Israel K2 - 15 june 2000) ( - International symposium on microelectronics and packaging ) (IMAPS RESTON, VIRGINIA USA ) - n. volume 146 - pp. da 8 a 13 ISBN: 9780930815615 ISSN: - [Abstract in Atti di convegno (274) - Abstract in Atti di Convegno]
Abstract

Pastes prepared with seven lead-free glass particles were screen-printed and fired on 96%-Al2O3 substrates. The fired films were studied in terms of sintering, devitrification, crack propagation and bleeding. The most promising glass compositions were selected for the preparation of RuO2-based tghick-film resistors (TFRs), on pre-fired PtAu - or PdAg based terminations; electrical properties of resistors (Rsvs:RuO2 volume fraction, temperature coefficient of resistanceand size effects) were investigated. The study eviced a myriad of complex phenomena occuring in the films, and emphasized the criticality in the choice of glass composition.

Ferrari, Anna Maria; Bonamartini Corradi, Anna; Bondioli, Federica; Tamburini, Umberto Anselmo; Gualtieri, Alessandro ( 2000 ) - Rietveld structure refinement of Pr doped zirconia ( 6th European Powder Diffraction Conference - TECH UNIV, BUDAPEST, HUNGARY - AUG 22-25, 1998) ( - EUROPEAN POWDER DIFFRACTION, PTS 1 AND 2 ) - n. volume 321-324 - pp. da 932 a 937 ISBN: 0-87849-847-8 ISSN: 0255-5476 [Contributo in Atti di convegno (273) - Relazione in Atti di Convegno]
Abstract

This work deals with the synthesis and Rietveld structure refinement of a zirconium-praseodymium yellow pigment prepared either by a traditional ceramic process route and by an unconventional synthesis method based on SHS (Self-Propagating High-Temperature Synthesis). in order to confirm the effective formation of the solid solutions, SEM imaging and EDS analysis, and leaching tests have also been performed. The results proved the applicability of the unconventional processing route for obtaining yellow solid solutions.

A.F. Gualtieri; E. Mazzuccato; P. Venturelli; A. Viani; P. Zannini; L. Petras ( 1999 ) - Determination of Nichel(II) oxide in ceramic pigments (-BLACKWELL PUBLISHING, 9600 GARSINGTON RD, OXFORD, ENGLAND, OXON, OX4 2DQ -American Ceramic Society:735 Ceramic Place:Westerville, OH 43081:(614)890-4700, (614)794-5890, EMAIL: customersrvc@acers.org, INTERNET: http://www.acers.org, Fax: (614)899-6109 ) - JOURNAL OF THE AMERICAN CERAMIC SOCIETY - n. volume 82 - pp. da 2566 a 2568 ISSN: 0002-7820 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Determination of Nichel(II) oxide in ceramic pigments, by means of high temperature XRD

Gualtieri, Alessandro; Passaglia, Elio; Galli, Ermanno; A., Viani ( 1999 ) - Rietveld structure refinement of Sr-exchanged phillipsites - MICROPOROUS AND MESOPOROUS MATERIALS - n. volume 31 - pp. da 33 a 43 ISSN: 1387-1811 [Articolo in rivista (262) - Articolo su rivista]
Abstract

The structures of three Sr-exchanged phillipsites with different Si/(Si+Al) ratio were refined by the Rietveld method on data collected with a conventional Bragg-Brentano geometry. The distribution of Sr in the extra-framework sites depends on its amount in the sample and hence on the value of Si/(Si+Al). The typical PZ,lin cell with Sr distributed over sites I and II is displayed in the two samples with Si/(Si+Al) = 0.72 and 0.76 respectively. The sample with Si/(Si+Al) = 0.63 instead undergoes a cell modification with Sr distributed in an ordered fashion in sites I, I', II, and II' of four adjacent cavities along the a axis. This ordered site distribution has the effect of changing the typical unit cell with a approximate to 9.8 Angstrom, b approximate to 14.0 Angstrom, c approximate to 8.6 Angstrom, and beta approximate to 124 degrees to a pseudo B-centered monoclinic cell with a approximate to 16.5 Angstrom, b approximate to 14.0 Angstrom, c approximate to 8.6 Angstrom and beta approximate to 99.4 degrees. Nevertheless, the B-centering is broken by the ordered extra-framework site distribution. This study may help in the understanding of the interaction mechanism of Sr-cation exchange in phillipsite for the potential use as a countermeasure amendment in radiostrontium-contaminated soils, and as sieve for Sr-90 in natural waters of nuclear facilities. (C) 1999 Elsevier Science B.V. All rights reserved.

AF Gualtieri; E. Mazzucato; P. Venturelli; A. Viani; P. Zannini; L. Petras ( 1999 ) - X-ray powder diffraction quantitative analysis performed in situ at high temperature: application to the determination of NiO in ceramic pigments - JOURNAL OF APPLIED CRYSTALLOGRAPHY - n. volume 32 - pp. da 808 a 813 ISSN: 0021-8898 [Articolo in rivista (262) - Articolo su rivista]
Abstract

Although nickel(II) oxide (NiO) is a potential carcinogenic agent, it is still used in the synthesis of ceramic pigments because during their preparation at high temperature, NiO is thought to combine with other compounds, crystallizing as new phases with spinel-like structures. Unfortunately, there are no widely accepted methods for the determination of free NiO in ceramics, the main reason being experimental difficulties. In fact, quantitative phase analysis (QPA) by X-ray powder diffraction (XRPD) may fail because diffraction peaks of NiO with space group Fm (3) over bar m and a similar or equal to 4.18 Angstrom overlap with those of the spinel with space group Fd (3) over bar m and a similar or equal to 8.4 Angstrom. To overcome this problem, in this work QPA has been performed in situ at high temperature to resolve the peak overlap of NiO and spinel by taking advantage of the different thermal expansion of each phase. It is believed that this is the first report of the application of this technique.

Immovilli S; Morten B; Prudenziati M; Gualtieri A; Bersani M ( 1998 ) - Interactions between bismuth oxide and ceramic substrates for thick film technology - JOURNAL OF MATERIALS RESEARCH - n. volume 13 - pp. da 1865 a 1874 ISSN: 0884-2914 [Articolo in rivista (262) - Articolo su rivista]
Abstract

We investigated the interactions between screen printed and fired layers of Bi2O3 and ceramic substrates of alumina and beryllia. It was found that the reaction products are invariably crystalline in nature. Several transitions of Bi2O3 in its polymorphic phases were found to occur on BeO substrates, while newly formed compounds have been observed to grow on alumina substrates, i.e., Al4Bi2O9 on 99.9% Al2O3 and Bi12SiO20 On 96% Al2O3 Bismuth deeply penetrates in the ceramic interstices in all the cases. Until Bi2O3 is not completely reacted, this penetration is diffusion limited (penetration depth w approximate to t(d)(1/2), where t(d) is the reaction time) with values of the activation energy ranging from 3.7 +/- 0.6 eV (BeO substrate) to 1.4 +/- 0.06 eV (96% Al2O3 substrate). It is shown that these processes are notably different to those occurring in PbO/ceramic systems; moreover, they imply different adhesion phenomena of thick films on different substrates.

M. Bersani; B. Morten; M. Prudenziati; A. F. Gualtieri ( 1997 ) - Interactions between lead oxide and ceramic substrates for thick film technology - JOURNAL OF MATERIALS RESEARCH - n. volume 12 - pp. da 501 a 508 ISSN: 0884-2914 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper deals with the mechanisms and kinetics of interactions between screen printed and fired PbO layers and ceramic substrates: alumina and beryllia. The interaction with alumina occurs via two main processes: (i) a reaction between PbO and Al2O3 grains, which induces the formation of a crystalline phase, Pb2Al2O5; and (ii) an interdiffusion process involving Pb and the intergranular amorphous phase in the ceramic substrate. This latter process results in a compositional change of the intergranular phase at considerable depths inside the ceramic substrate, as well as in the formation of a high lead glass layer on the substrate surface. Since PbO is not completely reacted, the Pb penetration in the ceramic is diffusion limited (penetration depth w proportional to the quare root of td, where td is the reaction time) with an activation energy of 1.20 ±0.05 eV. The ceramic microstructure significantly affects the interaction processes.

Bersani M; Morten B; Prudenziati M; Gualtieri A ( 1997 ) - Interactions between lead oxide and ceramic substrates for thick film technology - JOURNAL OF MATERIALS RESEARCH - n. volume 12 - pp. da 501 a 508 ISSN: 0884-2914 [Articolo in rivista (262) - Articolo su rivista]
Abstract

This paper deals with the mechanisms and kinetics of interactions between screen printed and fired PbO layers and ceramic substrates: alumina and beryllia. The interaction with alumina occurs via two main processes: (i) a reaction between PbO and Al2O3 grains, which induces the formation of a crystalline phase, Pb2Al2O5; and (ii) an interdiffusion process involving Pb and the intergranular amorphous phase in the ceramic substrate. This latter process results in a compositional change of the intergranular phase at considerable depths inside the ceramic substrate, as well as in the formation of a high lead glass layer on the substrate surface, Since PbO is not completely reacted, the Pb penetration in the ceramic is diffusion limited (penetration depth w approximate to t(d)(1/2) where t(d) is the reaction time) with an activation energy of 1.20 +/- 0.05 eV. The ceramic microstructure significantly affects the interaction processes.