Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-30T06:59:41.517Z Has data issue: false hasContentIssue false
  • English
  • Français

Solubility of Niobium(V) under Cementitious Conditions: Importance of Ca-niobate

Published online by Cambridge University Press:  17 March 2011

Caterina Talerico ,
Michael Ochs  and
Eric Giffaut
Caterina Talerico
Affiliation:
BMG Engineering Ltd., Ifangstrasse 11, CH-8952 Schlieren-Zürich, Switzerland
Michael Ochs
Affiliation:
BMG Engineering Ltd., Ifangstrasse 11, CH-8952 Schlieren-Zürich, Switzerland, [email protected]
Eric Giffaut
Affiliation:
ANDRA, Parc de la Croix Blanche, 1/7 rue Jean Monnet, F-92298 Châtenay-Malabry, France
Get access

Abstract

The solubility of niobium was investigated for Ca and pH conditions relevant for cementequilibrated solutions. For the pH range considered (9.5-13.2), the dissolved Nb concentration decreases with increasing pH. Overall, experiments lead to Nb concentrations between 2·10-5 M and 2·10-9 M. For all pH values, the dissolved Nb concentration also decreases systematically with increasing Ca concentration. X-ray diffraction measurements of selected experiments confirmed the presence of a solid Ca-Nb-oxide phase, with CaNb4O11·8H2O (hochelagaite) being the most likely composition. On the basis of these findings an empirical regression model for the prediction of Nb solubility data as a function of pH and Ca concentration was derived. This empirical relation is consistent with the presence of a solubility limiting Ca-Nb solid phase and permits to predict aqueous Nb solubility values in cementitious environments over a relatively wide range of conditions. Predicted values are in good agreement with independent experimental results.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 824: Symposium CC – Scientific Basis for Nuclear Waste Management XXVIII , 2004 , CC8.31
Copyright
Copyright © Materials Research Society 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Berner, U., Nagra Technical Report NTB 02-22, Wettingen, Switzerland (2003).Google Scholar
2. Baston, G. M. N., Brownsword, M., Smith, A.J. and Smith-Briggs, J. L., Nirex Report NSS/R357, Nirex, UK (1996).Google Scholar
3. Kulmala, S. and Hakanen, M., YJT-93-21, Helsinki, Finland (1993).Google Scholar
4. Baker, S., McChrohon, R., Oliver, P. and Pilkington, N.J., Mat. Res. Soc. Proc. Vol., 333, 719–724 (1994).Google Scholar
5. Neall, F., Nagra Technical Report NTB 94-03, Wettingen, Switzerland (1994).Google Scholar
6. Berner, U., MIN_SURF, PSI Internal Report, Paul Scherrer Institute, Villigen, Switzerland (1993).Google Scholar
7. Westall, J., Zachary, J. L. and Morel, F., MINEQL: A computer program for the calculation of chemical equilibrium composition of aqueous systems, Technical Note 18, Dept of Civil Eng., Massachusetts, Institute of Technology, Cambridge, Massachusetts (1976).Google Scholar
8. Cox, J. D., Wagman, D. D., Medvedev, V. A., CODATA key values for thermodynamics, Hemishere, New York (1989).Google Scholar
9. McClune, W. F., ed., Powder diffraction file –inorganic phases, alphabetical name, International Centre for Diffraction Data, Swarthmore, Pennsylvania, USA (1982).Google Scholar
10. Hummel, W., Berner, U., Curti, E., Pearson, F.J. and Thoenen, T., Nagra/PSI chemical thermodynamic data base 01/01, Universal Publishers, Parkland, Florida (2002).Google Scholar