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Enhancement of the Glass Corrosion in the Presence of Clay Minerals: Testing Experimental Results with an Integrated Glass Dissolution Model

Published online by Cambridge University Press:  01 January 1992

Enzo Curti ,
N. Godon  and
E.Y. Vernaz
Enzo Curti
Affiliation:
Paul Scherrer Institut, Villigen and Wdirenlingen, 5232 Villigen PSI, Switzerland
N. Godon
Affiliation:
CEN-VALRHO, B.P. 171, 30205 Bagnols-sur-Cèze Cedex, France
E.Y. Vernaz
Affiliation:
CEN-VALRHO, B.P. 171, 30205 Bagnols-sur-Cèze Cedex, France
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Abstract

Recent glass dissolution experiments, conducted at 90°C in the presence of potential backfill materials, indicate remarkably faster glass corrosion in the presence of clay, compared to tests where the glass is leached either alone or with alternative backfill materials. This effect correlates with the clay content in the backfill, and may be attributed to the removal of silica from solution. Sorption, or dissolution with reprecipitation of a silica-rich clay, have been proposed as possible mechanisms for the silica consumption.

The results of some experiments have been tested against a glass dissolution model, in which a widely used kinetic equation for glass corrosion is coupled with diffusive silica transport through a single porosity, linearly sorbing medium, which represents the backfilling. Because the glass corrosion rates imposed by the kinetic equation are inversely proportional to the silicic acid concentration of the leachant contacting the glass, the model predicts enhanced glass dissolution if silica is sorbed by the porous medium.

The experimental data proved to be consistent with the predicted enhancement of the glass dissolution. Moreover, the model-estimated distribution coefficients for silica sorption (Kd) fall within the range of values extracted from available literature data, thus supporting the hypothesis that the observed high corrosion rates are due to sorption of silica on the clay mineral surfaces.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 294: Symposium V – Scientific Basis for Nuclear Waste Management XVI , 1992 , 163
Copyright
Copyright © Materials Research Society 1993

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References

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