Structure and dynamics of Cs+ in kaolinite: Insights from molecular dynamics simulations

Abstract

In the present study, the adsorption and diffusion behaviors of Cs+ in kaolinite are investigated by classical molecular dynamics (MD) simulations with the effects of concentration, temperature, and competing cations. The obtained results turn out that Cs+ adsorbs preferentially on siloxane surface in the form of inner- and outer-sphere surface complexes. The adsorption percent of Cs+ diminishes with increasing concentration. Elevating temperature facilitates the adsorption of Cs+, while introduction of foreign cations weakens the interaction between siloxane surface and Cs+. It is indicated that the diffusion coefficient of Cs+ increases remarkably as the temperature rises. Nevertheless, varying concentration and competing cations have only slight effects on diffusion coefficient of Cs+. The results presented here can provide valuable insights into the interaction mechanism between Cs+ and kaolinite basal surfaces.