ION-EXCHANGE AND SORPTION KINETICS OF CESIUM AND STRONTIUM IN SOILS

The characteristics of sorption kinetics of cesium and strontium were studied via the batch method for some varieties of important crude soi ls in Taiwan, i.e. sorption mechanism and intraparticle diffusion coef ficients. Ion-exchange is the dominant reaction of Cs and Sr sorption for both soils chosen. In this study, the amount of exchanged cations was significantly affected by the mineral composition of soil. Experim ental results indicated that monovalent cations were more exchangeable for Ca sorption and divalent cations were more exchangeable for Sr so rption on both soils. The rate limiting processes of Cs and Sr sorptio n reaction on chosen soils were film diffusion-controlled The film dif fusion coefficients of Cs+ (D-FCs+) sorption on both soils were larger than those of strontium (D-FSr2+), in addition, the ratio of D-FCs+/D -FSr2+ is approximately equal to 4. The value revealed that the influe nce of ion charge on film diffusion is significant, and the film diffu sion coefficient increases as the nuclide charge decreases.