RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

The experimental investigation and modelling of radionuclide sorption processes is an essential part of safety analysis of an underground repository for radioactive wastes. Interactions at solid/liquid interfaces play a significant role in the speciation and transport of radionuclides in aquifer systems. The retention behaviour of Am (III) at trace concentration (10⁻⁸M) onto a alumina and amorphous silica has been studied at two ionic strengths in the pH range 4–9. In both systems the Am uptake increases with increasing pH. The ionic strength seems to have a minor effect on this sorption. A surface complexation model has been applied to the results and surface complexation constants have been determined in both systems.