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Fibrous silica gel obtained from sepiolite by HCl attack

Published online by Cambridge University Press:  09 July 2018

L. Gozález ,
L. M. Ibarra ,
A. Rodríguez ,
J. S. Moya  and
F. J. Valle
L. Gozález
Affiliation:
Instituto de Plásticos y Caucho, CSIC, c/Juan de la Cierva, 3 Madrid-6
L. M. Ibarra
Affiliation:
Instituto de Plásticos y Caucho, CSIC, c/Juan de la Cierva, 3 Madrid-6
A. Rodríguez
Affiliation:
Instituto de Plásticos y Caucho, CSIC, c/Juan de la Cierva, 3 Madrid-6
J. S. Moya
Affiliation:
Instituto de Cerámica y Vidrio, CSIC, Arganda del Rey, Madrid, Spain
F. J. Valle
Affiliation:
Instituto de Cerámica y Vidrio, CSIC, Arganda del Rey, Madrid, Spain
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Extract

Sepiolite is an Mg-silicate with fibrous morphology. Its structure consists of talc-like ribbons parallel to the fibre axis. Although the tetrahedral sheets are continuous, the apices in adjacent ribbons point in opposite directions, each ribbon alternating with an open channel along the fibre axis. Tetrahedral positions are normally filled with Si atoms. The width of the ribbons corresponds to eight octahedral positions, which are, normally occupied by Mg atoms, and the channel cross-section is 3·8 x 9·4 Å. This structure gives the mineral a high adsorptive capacity and molecular sieve capability. The ideal mineralogical formula is (OH2)4(OH)4Mg8Si12O30.8H2O (Brauner & Preisinger, 1956).

Activation of sepiolite by acid attack has been extensively studied (Fernández-Alvarez, 1972; Jiménez-López et al., 1978; Rodríguez-Reinoso et al., 1981). This note describes the changes undergone by sepiolite during dissolution of the octahedral Mg-sheet by HCl attack, silica gel being the end-product. This process was followed by IR spectroscopy, study of Mg-extraction kinetics, and morphological observations by SEM and TEM.

Type
Notes
Information
Clay Minerals , Volume 19 , Issue 1 , February 1984 , pp. 93 - 98
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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References

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