Cesium uptake by Ca/Mg bentonite: evaluation of sorption experiments by a multicomponent two-site ion-exchange model

Cesium sorption on Czech Ca/Mg bentonite was studied using the batch technique for a wide range of both bentonite-to-water ratios (m/V) and initial concentrations of Cs. The experiments revealed non-linear pattern of cesium sorption, which was substantially influenced by the m/V. The results of the exchange reaction between added Cs+ and Mg2+, Ca2+, Na+ and K+ ions present naturally on the bentonite sorption sites enabled to determine the appropriate selectivity coefficients. The capacity of sites with higher selectivity to cesium, which is believed to be associated with the frayed-edge sites, was measured using the AgTU method.