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Textural and structural modifications of saponite from Cerro del Aguila by acid treatment

Published online by Cambridge University Press:  09 July 2018

M. Suárez Barrios ,
C. de Santiago Buey ,
E. García Romero  and
J. M. Martín Pozas
M. Suárez Barrios*
Affiliation:
Area de Cristalografía y Mineralogía, Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced S/N, E-37008-Salamanca, Spain
C. de Santiago Buey
Affiliation:
Departamento de Cristalografía y Mineralogía, Facultad de Geología, Universidad Complutense de Madrid, Ciudad Universitaria, MadridSpain
E. García Romero
Affiliation:
Departamento de Cristalografía y Mineralogía, Facultad de Geología, Universidad Complutense de Madrid, Ciudad Universitaria, MadridSpain
J. M. Martín Pozas
Affiliation:
Area de Cristalografía y Mineralogía, Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, Plaza de la Merced S/N, E-37008-Salamanca, Spain
*
*E-mail: [email protected]
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Abstract

The physicochemical properties of clays can be modified by acid treatment with inorganic acids. This treatment is usually referred to as ‘acid activation’, because it increases the specific surface area and the number of active sites of the solids. In the present study, the acid activation of saponite from Cerro del Aguila (Madrid, Spain) with HCl solutions was measured. Illite, quartz and small amounts of feldspar were found as impurities in the raw saponite.

Acid treatments were carried out with different concentrations of HCl solutions. The samples obtained were characterized by mineralogical and chemical analyses, XRD, FT-IR spectroscopy, N2 adsorption-desorption isotherms and TEM. The acid attack, under the conditions employed, produced a progressive destruction of the structure of saponite by partial dissolution of the octahedral Mg(II) cations. Amorphous silica coming from the tetrahedral sheet of saponite was generated. The specific surface area of the most intensely treated sample (2.5% for 24 h) was doubled with respect to that of natural saponite. This increase in the surface area is due to the increase in both the external and internal surface areas.

Keywords

bentonitesaponiteacid activationtransmission electron microscopySpain
Type
Research Article
Information
Clay Minerals , Volume 36 , Issue 4 , December 2001 , pp. 483 - 488
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2001

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