Adsorption Kinetics of Cs/Sr on Ca-Bentonite.

137Cs+/90Sr2+ adsorption kinetics on natural Ca-bentonite under the impact of different adsorption conditions was examined in detail. The results indicate that natural Ca-bentonite shows a strong adsorption capacity for Cs+/Sr2+. The adsorption reached at equilibrium after 2 hours for Cs+. Cs+/Sr2+removal efficiency reaches the highest when the pH value is 5 to 8 and increases with the increase of Ca-bentonite adding amount. Cs+ removal efficiency increases with the increase of Cs+ initial concentration, while Sr2+ removal efficiency slightly varies around 70%. The adsorption of Cs+/Sr2+ by Ca-bentonite follows the pseudo-second-order model and is controlled by chemical adsorption. Meanwhile, the results of intraparticle diffusion modelling indicate that intraparticle diffusion is a kinetics controlling step, besides surface adsorption and liquid film diffusion.