Study of cesium sorption on Na and Ca-Mg bentonites using batch and diffusion experiments

Abstract

In this study the cesium sorption on two different bentonites (Ca-Mg bentonite Rokle and Na bentonite Volclay KWK 20-80) has been compared using two different experimental approachesbatch and diffusion methods. The distribution coefficients (K d s) calculated for variable liquid-tosolid ratio (batch) and dry density (diffusion) were evaluated with respect to the main uncertainties affecting both approaches. It has been concluded that there are significant differences between selected bentonites in mineral composition, cation exchange capacity (CEC) and sorption characteristics. The K d values calculated from batch sorption and diffusion data were found comparable only for Na bentonite Volclay KWK 20-80. The considerably higher sorption of Cs on Ca-Mg bentonite Rokle was explained by its higher content of cesium-selective sorbents (illite, vermiculite).