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Experimental Indications of Effects of Surface Deprotonation on Na-Bentonite Porewater Chemistry in a Geological Repository

Published online by Cambridge University Press:  21 March 2011

C. Oda ,
M. Shibata  and
M. Yui
C. Oda
Affiliation:
Japan Nuclear Cycle Development Institute, Tokai, Ibaraki, Japan. Email: chie@tokai.jnc.go.jp
M. Shibata
Affiliation:
Japan Nuclear Cycle Development Institute, Tokai, Ibaraki, Japan. Email: chie@tokai.jnc.go.jp
M. Yui
Affiliation:
Japan Nuclear Cycle Development Institute, Tokai, Ibaraki, Japan. Email: chie@tokai.jnc.go.jp
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Abstract

Bentonite-water interaction was studied using a simple equilibrium model based on experimental measurements in order to describe bentonite porewater chemistry. Direct pH measurements for highly compacted bentonite and batch-type bentonite-water interaction experiments were performed under anaerobic conditions. In the direct pH measurements, resin particles doped with a pH indicator were sandwiched between a pair of bentonite columns immersed in a test solution. The experimental results showed that the solution compositions in equilibrium with bentonite depended on the bentonite to liquid ratio (B/L) and the initial solution composition. An equilibrium model assuming only fast equilibration processes between the bentonite minerals and the solution could be used to calculate the trends of pH and other ion concentrations with B/L. This study indicates that the surface deprotonation of smectite is a very important factor influencing the porewater chemistry in highly compacted bentonite.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 637
Copyright
Copyright © Materials Research Society 2001

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References

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