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Dehydration behaviour of heulandite-group zeolites as a function of their chemical composition

Gloria Valueva
Dehydration behaviour of heulandite-group zeolites as a function of their chemical composition
European Journal of Mineralogy (December 1995) 7 (6): 1411-1420

Abstract

The results are reported for thermochemical studies on the dehydration process in 17 samples of natural heulandites covering the entire range of chemical compositions (heulandites 1,2,3) [A.M. 57-1448, 1463]. In each sample, a sudden change in the thermodynamic properties (heat capacity of heulandite, partial molar entropy of H (sub 2) O, entropy production during dehydration) was detected at particular H (sub 2) O contents. The direction of this change suggests a straining of the structure leading to a lowering of its entropy (i.e. ordering in the thermodynamic sense); the changes detected are interpreted as synergetic phase transitions. Correlations are found not only between the chemical compositions of the samples and the thermodynamic characteristics of the dehydration process, but also with the H (sub 2) O content at which the phase transition begins. These correlations are different for heulandites 1 and 2 and clinoptilolite (heulandite 3), suggesting a difference in their dehydration mechanism; this makes it possible to discriminate between them more precisely according to their chemical compositions.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 6
Title: Dehydration behaviour of heulandite-group zeolites as a function of their chemical composition
Author(s): Valueva, Gloria
Affiliation: Institute of Mineralogy and Petrography, Novosibirsk, Russian Federation
Pages: 1411-1420
Published: 199512
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 23
Accession Number: 1996-014814
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199606
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