Kinetics of the dehydroxylation and mullitization processes of the halloysite from the Farbani Potok locality, Serbia

Prodanovic, Danica; Živković, Živan; Radosavljević, S.

doi:10.1016/s0169-1317(97)00011-2

Cited by 29 publications

(14 citation statements)

References 7 publications

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“…The same is true for the band at 562 cm -1 , which is observed in the spectra of halloysite but not for the hydrated halloysite. Finally, the halloysite spectrum presents slightly longer and narrower bands than those of the spectrum for hydrohalloysite; this difference could be caused by the presence of 1034 cm -1 band (Prodanovic et al 1997). …”

Section: Raman and Infrared Spectrometrymentioning

confidence: 85%

Mineralogical and geochemical studies of hardened subsurface layers in soils of the Azufres and Atecuaro volcanic calderas, southwestern Mexico

Ostrooumov¹,

Monroy²,

Servenay³

2005

Can. J. Soil. Sci.

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Ostrooumov, M., Monroy, V. H. G. and Servenay, A. 2005. Mineralogical and geochemical studies of hardened subsurface layers in soils of the Azufres and Atecuaro volcanic calderas, southwestern Mexico. Can. J. Soil Sci. 85: 611-624. Free silica and halloysite-bearing hardened subsurface layers in the ash fall deposits of the Azufres and Atecuaro volcanic calderas (Michoacan State, southwestern Mexico), known as "tepetates", have been characterized by chemical analysis, X-ray diffraction (XRD), Raman and Infrared spectrometry, optical (OM) and scanning (SEM) microscopy with energy dispersive X-ray analysis (EDXRA). Chemical analysis of these weathered and hardened formations shows the oxidation of Fe 2+ , enrichment of Al, Fe 3+ and Ti, loss of Si, Na, Ca, K, Mg, and formation of minerals with hydroxyls groups. Tepetates are characterized by elevated SiO 2 /Al 2 O 3 molar ratios (4. 86-8.82) that show part of the SiO 2 has crystallized in free siliceous phases. X-ray analysis reveals hydrated (1.0 nm) and dehydrated halloysite (0.7 nm), sanidine, plagioclases, cristobalite, and tridymite. Raman and infrared spectra confirm the presence of these mineral phases and show that the structural transformations occur in opal neoformations. SEM shows a compact matrix with a skeleton of different phenocrysts (aluminosilicates, ferromagnesian minerals and various crystalline silica phases) and the presence of non-crystalline silica (volcanic glass and opal with different degrees of crystallinity). The tepetates form by interaction of two processes: volcanic ash fall then subsequent weathering under variable climatic conditions. These indurated horizons are partly or totally cemented by the diagenetic secondary minerals: non-crystalline silica with variable crystal chemical characteristics and clay minerals. . Ils ont pour cela recouru à l'analyse chimique, à la diffraction par rayons X, à la spectrométrie Raman et à infrarouge, à la microscopie photonique et par balayage (MB) ainsi qu'à l'analyse radiologique par dispersion d'énergie. L'analyse chimique de ces formations durcies et altérées révèle l'oxydation du Fe 2+ , un apport d'Al, de Fe 3+ et de Ti, la perte de Si, Na, Ca, K et Mg, et la formation de minéraux à groupes hydroxyles. Les tepetates se caractérisent par un ratio molaire élevé de SiO 2 /Al 2 O 3 (4,86 à 8,82), signe qu'une partie du SiO 2 s'est cristallisée dans la silice libre. L'analyse radiologique révèle de l'halloysite hydratée (1,0 nm) et déshydratée (0,7 nm), de la sanidine, des plagioclases, de la cristobalite et de la tridymite. L'analyse par spectrométrie Raman et infrarouge confirme la présence de ces phases minérales et montre que les transformations structurales surviennent dans les néoformations d'opales. La MB montre une matrice compacte ayant pour squelette différents phénocristaux (aluminosilicates, minéraux ferro-magnésiens et diverses phases de silice cristalline) ainsi que la présence de silice non cristalline (verre volcanique et opales à cristallinité variable). Les tepetates naissent ...

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Section: Raman and Infrared Spectrometrymentioning

confidence: 85%

Mineralogical and geochemical studies of hardened subsurface layers in soils of the Azufres and Atecuaro volcanic calderas, southwestern Mexico

Ostrooumov¹,

Monroy²,

Servenay³

2005

Can. J. Soil. Sci.

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“…The linearized form of Equation takes the form of Equation , which is the Kissinger‐Akahira‐Sunose equation …”

Section: Methodsmentioning

confidence: 99%

Effect of specimen geometry on kinetics of thermal decomposition of minerals in porous ceramic tiles

Cargnin

Kammer

Souza

et al. 2019

Int J Applied Ceramic Tech

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Porous ceramic tiles are used as covering for indoor vertical surfaces in buildings. Clay and limestone are the starting raw materials. The firing step consolidates the product's properties in the manufacturing process. In this step several reactions occur, among them are the dehydroxylation of the clay minerals and decomposition of the carbonates. This study determined the kinetics parameters associated with the decomposition of these 2 minerals. Two different methods of samples preparation were investigated. In the first method, 60 mg of a spray‐dried powder was submitted to analysis in traditional thermogravimetric equipment. In the second method, compacted specimens with dimensions of 80 × 20 × 2.5 mm³ and a mass of 7 g, compacted at 25 MPa, were submitted to analysis using customized thermogravimetric apparatus. The curves were obtained for 6 different heating rates between 2.5 and 20 K min−1. The activation energy, the pre‐exponential factor of the specific velocity equation, and the reaction mechanism were determined. Depending on the methods and compaction degree the activation energy varies from 177.0 to 224.7 kJ mol−1 and from 188.5 to 230.2 kJ mol−1 for kaolinite and calcium carbonate, respectively. For accurate measurement of the activation energy, the heat transfer needs to be considered for each particular experimental configuration.

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“…3) showed that the standard body mix with feldspar as the fluxing agent still contained 3 main crystalline phases after firing at 900 • C. Reflections belonging to halloysite subsided significantly after firing at 1000 • C before finally disappearing at 1100 • C. According to a study of Prodanovi et al, thermochemical reactions of halloysite were relatively similar to those of kaolinite; dehydroxylation around 559 • C into metahalloysite prior to transforming to mullite at 988 • C. 10 Our finding was thus slightly different from that in the reported literature. At 1100 • C, intensity of the microcline reflections was also reduced appreciably while the emergence of mullite peaks could be observed.…”

Section: Phase Changes Upon Firingmentioning

confidence: 98%

Fluxing action of illite and microcline in a triaxial porcelain body

Wattanasiriwech

2011

Journal of the European Ceramic Society

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Kinetics of the dehydroxylation and mullitization processes of the halloysite from the Farbani Potok locality, Serbia

Cited by 29 publications

References 7 publications

Mineralogical and geochemical studies of hardened subsurface layers in soils of the Azufres and Atecuaro volcanic calderas, southwestern Mexico

Mineralogical and geochemical studies of hardened subsurface layers in soils of the Azufres and Atecuaro volcanic calderas, southwestern Mexico

Effect of specimen geometry on kinetics of thermal decomposition of minerals in porous ceramic tiles

Fluxing action of illite and microcline in a triaxial porcelain body

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