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Conductimetric investigations on the dissolution of metakaolinite in dilute hydrofluoric acid. Structural implications

Published online by Cambridge University Press:  09 July 2018

M. Murat  and
M. Driouche
M. Murat
Affiliation:
Institut National des Sciences Appliquees (INSA) de Lyon, Laboratoire de Chimie Physique Appliquee et Environment, Bat. 404, 20 av. A. Einstein, 69621 Villeurbarme Cedex, France
M. Driouche
Affiliation:
Institut National des Sciences Appliquees (INSA) de Lyon, Laboratoire de Chimie Physique Appliquee et Environment, Bat. 404, 20 av. A. Einstein, 69621 Villeurbarme Cedex, France
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Abstarct

Conductimetric curves based on dissolution in dilute HF of a series of metakaolinite samples prepared by thermal dehydroxylation of kaolinite in air from 500°C to 987°C, have been interpreted in terms of (i) short-time conductivity variation, and (ii) specific initial dissolution rate (rsi). The first parameter has been correlated with a disorganization factor (Fd, equal to unity for an entirely amorphous silica-alumina mix) which does not exceed 0·52 for metakaolinite and, like rsi, reaches a maximum for samples prepared at about 720–750°C. These results, which agree with other data obtained by calorimetry and infrared spectroscopy, show that metakaolinite is never entirely amorphous and has a degree of disorder which varies with the conditions of preparation, and increases for samples which have been mechanically treated by grinding.

Type
Research Article
Information
Clay Minerals , Volume 23 , Issue 1 , March 1988 , pp. 55 - 67
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1988

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