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Surface Site Densities of Uranium Oxides: UO2, U3O8

Published online by Cambridge University Press:  01 February 2011

F. Clarens ,
J. de Pablo ,
I. Casas ,
J. Giménez  and
M. Rovira
F. Clarens
Affiliation:
Chemical Engineering Department. Universitat Politècnica de Catalunya. 08028 Barcelona., Spain
J. de Pablo
Affiliation:
Chemical Engineering Department. Universitat Politècnica de Catalunya. 08028 Barcelona., Spain
I. Casas
Affiliation:
Chemical Engineering Department. Universitat Politècnica de Catalunya. 08028 Barcelona., Spain
J. Giménez
Affiliation:
Chemical Engineering Department. Universitat Politècnica de Catalunya. 08028 Barcelona., Spain
M. Rovira
Affiliation:
Chemical Engineering Department. Universitat Politècnica de Catalunya. 08028 Barcelona., Spain
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Abstract

The estimation of the surface site density for UO2 (main component of the SF matrix) is an important aspect to take into account in the development of radiolytical models for the dissolution of the spent nuclear fuel (SF). Also, other oxides can be formed on the SF surface due to the effect of radiolytically-formed oxidizing species. Due to the lack or reliable data in literature we have studied the surface site densities of two uranium oxides: UO2 and U3O8.

For this determination, the knowledge of both the reactive surface area and the surface charge of the solid are necessary. In this work the reactive surface area of the two solids was determined by the BET method while the surface charge was determined by potentiometric acid-base titrations of suspensions of the solids at different ionic strengths (0.001, 0.01, and 0.1 mol·dm−3) under N2 atmosphere.

The amount of adsorbed protons was calculated by subtracting blank titration from thesolid suspension titration. The single-site nonelectrostatic model (NEM) was used to describe titration data. Uranium speciation in solution was included in the model as well.

The surface area values obtained were 0.15 ± 0.01 m2·g−1 for UO2 and 0.77 ± 0.02 m2·g−1 for U3O8, while the surface acidic site densities were determined to be 165 ± 10 sites·nm−2 and 48 ± 3 sites·nm−2 for UO2 and U3O8, respectively.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 807: Symposium Scientific Basis for Nuclear Waste Management XXVII , 2003 , 71
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

1. Brunover, S., Emmett, P.H. and Teller, E. (1938) J. Am. Chem. Soc. 60, 309A.Google Scholar
2. Huertas, F.J., Chou, L. and Wollast, R. (1998) Geochim. et Cosmochim. Acta 62, 417.Google Scholar
3. Lu, W. and Smith, E.H. (1996) Geochim. et Cosmochim. Acta 60, 3363.Google Scholar
4. Ridley, M.K., Machesky, M.L., Wesolowski, D.J. and Palmer, D.A. (1999) Geochim. et Cosmochim. Acta 63, 3087.Google Scholar
5. Pokrovsky, O.S., Schott, J. and Thomas, F. (1999) Geochim. et Cosmochim. Acta 63, 3133.Google Scholar
6. Christl, I. and Kretzschmar, R. (1999) Geochim. et Cosmochim. Acta. 63, 19/20, 2929.Google Scholar
7. Liger, E., Charlet, L., and Van Cappellen, P. (1999) Geochim. et Cosmochim. Acta. 63, 19/20, 2939.Google Scholar
8. Sinitsyn, V.A., Aja, S.U., Kulik, D.A. and Wood, S.A. (2000) Geochim. et Cosmochim. Acta 64, 185.Google Scholar
9. Wanner, H., Albinsson, Y., Karnland, O., Wieland, E., Wersin, P. and Charlet, L. (1994) Radiochim. Acta 66/67, 157.Google Scholar
10. Herbelin, A.L. and Westall, J.C. (1996) FITEQL: a program for the determination of chemical equilibrium constants from experimental data. Report 96–01, Oregon State University.Google Scholar
11. Stumm, W. (1992) Chemistry of the Solid-Water Interface. Wiley.Google Scholar
12. Davis, J.A. and Kent, D.B. (1990) Surface complexation modeling in aqueous geochemistry. In: Review in Mineralogy: Mineral Water Interface, Vol. 23, Chap. 5, pp. 177.Google Scholar
13. Rossoti, H. (1978) The study of ionic equilibria. Longman Group Limited.Google Scholar
14. Gran, G. (1950) Acta Chem. Scand. 4, 559.Google Scholar
15. Gran, G. (1952) Int. Congress on Anal. Chem. 77, 661.Google Scholar
16. Grenthe, I., Fuger, J., Konings, R.J.M., Lemire, R.J., Muller, A.B., Nguyen-Trung, S. and Wanner, H. (1992) Chemical Thermodynamics of Uranium. OECD-NEA. Elsevier.Google Scholar
17. Forsgren, G. (1988) Development of a method for identification of the oxidation state of uranium oxide surfaces in aqueous media. Examensarbete TRITA-OOK-1022.Google Scholar
18. Bruno, J. and Cera, E. (1999) Modelo Conceptual del comportamiento del residuo. Enresa 2000. Versión 2.Google Scholar
19. de Pablo, J., Casas, I., Giménez, J., Molera, M., Rovira, M., Duro, L. and Bruno, J. (1999) Geochim. et Cosmochim. Acta 63, 3097.Google Scholar