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Actinide Sorption onto Silica in the Presence of Humic Substances: Proposal of Retentionmechanisms

Published online by Cambridge University Press:  25 February 2011

N. Labonne ,
V. Moulin  and
D. Stammose
N. Labonne
Affiliation:
Commissariat à I'Energie Atomique du Cycle du Combustible, Département Stockage Dérchets, 6 92265 Fontenay-aux-Roses Cedex, FRANCE
V. Moulin
Affiliation:
Commissariat à I'Energie Atomique du Cycle du Combustible, Département Stockage Dérchets, 6 92265 Fontenay-aux-Roses Cedex, FRANCE
D. Stammose
Affiliation:
Commissariat à I' Energie Atomique de Protection et de Sûreté Nuciéaire, BP 6 92265 Fontenay-aux-Roses Cedex, FRANCE
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Abstract

The experimental investigation and modelling of radionuclides sorption processes is an essential part of safety analyses of an underground repository of radioactive wastes in geological formations. Physico—chemical phenomena at oxide/solution interfaces have been studied in the case of the system constituted by amorphous silica and americium (III) in the presence of humic substances as organic complexing agents. The retention behaviour of Am(III) onto silica appears dependent on pH, ionic strength and in particular humic concentration. At a ionic strength of 0.1 M, the presence of low concentration of humic acids (1 mg/l) enhances the Am(III) retention in the pH range 3-5.5, whereas at higher pH, its uptake is largely decreased. At lower ionic strength (0.001 M), Am(III) retention on silica is highly lowered, in the pH range 3-7 in the presence of humic acids. Reversibility experiments show the desorption of americium in the absence of humic substances, and also the desorption of the humics on the silica with respect of the pH. The surface complexation model has been applied to our results in the different systems and apparent surface complexation constants have been determined.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 257: Symposium – Scientific Basis for Nuclear Waste Management XV , 1991 , 307
Copyright
Copyright © Materials Research Society 1992

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References

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