Water-uptake capacity of bentonites
Kaufhold, Stephan (BGR, Bundesanstalt für Geowissenschaften und Rohstoffe)
Dohrmann, Reiner (LBEG, Landesamt für Bergbau, Energie und Geologie)
Klinkenberg, M. (Institut für Energieforschung Sicherheitsforschung und Reaktortechnik (IEF-6). Forschungszentrum Jülich GmbH)

Fecha:	2010
Resumen:	The present study compares the water-vapor adsorption capacity of bentonites (natural cation population) with the Enslin-Neff method. Water-vapor adsorption at 50% r. h. (relative humidity) or 70% r. h. is known to depend heavily on the amount of permanent charge and on the type of exchangeable cation. At ~80% r. h. Na- and Ca/Mg-dominated bentonites take up equal amounts of water. Comparing the water-uptake capacity at 80% r. h. with the cation exchange capacity (CEC) revealed a close correlation between these two variables. Appreciable scatter apparent from this plot, however, suggests that additional factors influence the water-uptake capacity. Water adsorption at external surfaces was considered to be one of these factors and was, in fact, implicated by N-adsorption data. The ratio of external/internal water ranged from 0 to 1, which suggests that water-adsorption values cannot be applied in the calculation of the internal surface area without correction for external water. The Enslin-Neff water-uptake capacity, on the other hand, is unaffected by microstructural features (e. g. specific surface area and porosity). The amount of exchangeable Na is themost important factor. However, the relationship between the Na content and the Enslin value is not linear but may be explained by percolation theory.
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Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Bentonite ; Enslin-Neff ; Swelling Capacity ; Water-vapor Adsorption
Publicado en:	Clays and Clay Minerals, Vol. 58, Núm. 1 (2010) , p. 37-43, ISSN 1552-8367

DOI: 10.1346/CCMN.2010.0580103

7 p, 594.6 KB  Acceso restringido a la UAB

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