Water-Uptake Capacity of Bentonites
- 1 February 2010
- journal article
- Published by Cambridge University Press (CUP) in Clays and Clay Minerals
- Vol. 58 (1), 37-43
- https://doi.org/10.1346/ccmn.2010.0580103
Abstract
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 Ca2+/Mg2+-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-2-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 the most important factor. However, the relationship between the Na+ content and the Enslin value is not linear but may be explained by percolation theoryKeywords
This publication has 15 references indexed in Scilit:
- Detachment of colloidal particles from bentonites in waterApplied Clay Science, 2008
- Quantitative phase analysis of bentonites by the rietveld methodClays and Clay Minerals, 2008
- Comparison of methods for the determination of the layer charge density (LCD) of montmorillonitesApplied Clay Science, 2006
- Bestimmungsmethode der Konsistenzgrenzen mittels WasseraufnahmeversuchenBautechnik, 2006
- Der Wasseraufnahmeversuch nach DIN 18132 in einem neu entwickelten GerätBautechnik, 2005
- Swelling–shrinkage kinetics of MX80 bentoniteApplied Clay Science, 2003
- Layer Charge Influences on the Hydration of Expandable 2:1 PhyllosilicatesClays and Clay Minerals, 1999
- Mechanism of Adsorption and Desorption of Water Vapor by Homoionic Montmorillonite: 3. The Mg2+, Ca2+, Sr2+ and Ba2+ Exchanged FormsClays and Clay Minerals, 1997
- The effect of tetrahedral substitution of Si by Al on the surface acidity of the oxygen plane of clay mineralsInternational Reviews in Physical Chemistry, 1992
- Structure of water adsorbed on smectitesChemical Reviews, 1982