SORPTION OF IODINE AND CESIUM ON SOME MINERAL OXIDE COLLOIDS

The sorption of I-131 and Cs-137 at tracer level on three mineral oxid e colloids, SiO2, TiO2 and Al2O3, has been investigated under various pH (2 to 11) and ionic strength (10(-3) to 0.1 M) conditions. A correl ation has been established between the sorption ratios and the colloid al zeta-potentials, reflecting surface charge and kinetic stability. S orption ratios result from colloidal and aqueous phase partition, at e quilibrium, of each radionuclide. Thus, electrostatic effects have bee n shown to be involved in the sorption processes under consideration; however, they cannot alone explain all of the results and the surface complexation theory has then been applied. A good fitting of the main results has been obtained, by using a simple constant capacitance mode l (FITEQL code).