Adsorption and diffusion mechanism of Cs+ by potassium copper ferrocyanide-functionalized mesoporous silica channels: Molecular dynamics simulations

Abstract

In this study, the adsorption and diffusion behavior of Cs⁺ on mesoporous silica channels loaded with potassium copper ferrocyanide was investigated by molecular dynamics simulations, considering the effects of the size of the loaded group, the solution concentration, and the competing cation. The results show that Cs⁺ is preferentially adsorbed around the nitrogen atoms on the surface of the group in the form of inner and outer sphere surface complexes. Large-sized groups provide more active sites, but these sites may be masked, especially if groups block the channels. The introduction of foreign cations, especially divalent cations, weakened the interaction between the functional groups and Cs⁺. The mean square displacement and diffusion coefficients indicate that the diffusion range of Cs⁺ increases with increasing concentration and the addition of competing ions, revealing that the stronger the adsorption of Cs⁺ by the channel, the lower the diffusion capacity of Cs⁺.