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Diffusion Behavior of Ca2+ Ions in Compacted Na-Montmorillonite

Published online by Cambridge University Press:  21 March 2011

Tamotsu Kozaki ,
Yoshifusa Adachi ,
Koichi Inada ,
Seichi Sato  and
Hiroshi Ohashi
Tamotsu Kozaki
Affiliation:
Division of Quantum Energy Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan
Yoshifusa Adachi
Affiliation:
Division of Quantum Energy Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan
Koichi Inada
Affiliation:
Division of Quantum Energy Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan
Seichi Sato
Affiliation:
Division of Quantum Energy Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan
Hiroshi Ohashi
Affiliation:
Division of Quantum Energy Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, 060-8628, Japan
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Abstract

Diffusion behavior of Ca2+ ions in water-saturated, compacted Na-montmorillonite was studied for the safety assessment of geological disposal of high-level radioactive waste. The diffusion coefficients of Ca2+ ions in compacted Na-montmorillonite obtained in this study were from 1.7×10-11 to 6.0×10-12 m2 s-1 with increasing dry density of 1.0 to 1.8 Mg m-3. These values were approximately a quarter those of Na+ ions at each dry density. This suggests that the diffusion of Ca2+ ions could be the rate-determining mechanism for the alteration of Na-montmorillonite into Ca-montmorillonite. The activation energy for diffusion of Ca2+ ions was almost equal to that in free water (17.3 kJ mol-1) at dry densities of 1.0 to 1.6 Mg m-3. However, the activation energy suddenly increased to 25.1 kJmol-1 at a dry density of 1.8 Mg m-3. This increase cannot be explained using a single-diffusion process model, such as the pore-water diffusion model. Diffusion behavior of Ca2+ ions in compacted montmorillonite along with the experimental data on the basal spacing and water content of montmorillonite, and the activation energy for diffusion of Ca2+ and several other ions are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 629
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

1.Power Reactor and Nuclear Fuel Development Corporation, PNC TN1410 93-059, 1992.Google Scholar
2. Oscarson, D. W., Clays Clay Miner., 42, 534(1994).Google Scholar
3. Kozaki, T., Sato, H., Fujishima, A., Sato, S., and Ohashi, H., J. Nucl. Sci. Technol., 33, 522(1996).Google Scholar
4. Kozaki, T., Fujishima, A., Sato, S., and Ohashi, H., Nucl. Technol., 121, 63(1998).Google Scholar
5. Kozaki, T., Sato, H., Fujishima, A., Saito, N., Sato, S., and Ohashi, H., in Scientific Basis for Nuclear Waste Management XX, edited by Gray, W. J. and Triay, I. R., (Mater. Res. Soc. Proc. 465, Pittsburgh, PA, 1997) pp.893–900.Google Scholar
6. Kozaki, T., Saito, N., Fujishima, A., Sato, S., and Ohashi, H., J. Contam. Hydrol., 35, 67 (1998).Google Scholar
7. Kozaki, T., Inada, K., Sato, S., and Ohashi, H., J. Contam. Hydrol., (in printing).Google Scholar
8. Crank, J., The Mathematics of Diffusion, 2nd ed.(Clarendon Press, Oxford, 1975) pp.11–21.Google Scholar
9. Sato, H., Ashida, T., Kohara, Y., Yui, M., and Sasaki, N., J. Nucl. Sci. Technol., 29, 873(1992).Google Scholar
10. Robinson, R. A. and Stokes, R. H., Electrolyte Solutions, 2nd ed., (Butterworths, London, 1959) p.465.Google Scholar
11. Parsons, R., Handbook of Electrochemical Constants, (Butterworths Scientific Publications, London, 1959) p.79.Google Scholar
12. Gast, R. G., Soil Sci. Soc. Amer. Proc., 36, 14(1972).Google Scholar
13. Kato, H., Muroi, M., Yamada, N., Ishida, H., and Sato, H., in Scientific Basis for Nuclear Waste Management XVIII, edited by Murakami, T. and Ewing, R. C., (Mater. Res. Soc. Proc. 353, Pittsburgh, PA, 1995) pp.277–284.Google Scholar
14. Cole, T., Bidoglio, G., Soupioni, M., M. O.Gorman, and Gibson, N., Geochim. Cosmochim. Acta, 64, 385(2000).Google Scholar
15. Dufey, J. E., Banin, A., Laudelout, H. G., and Chen, Y., Soil Sci. Soc. Amer. J., 40, 310(1976).Google Scholar
16. Kozaki, T., Sato, H., Sato, S., and Ohashi, H., Eng. Geol., 54, 223 (1999).Google Scholar
17. Kozaki, T., Fujishima, A., Sato, H., Sato, S., and Ohashi, H., (in manuscript).Google Scholar