Cs+ sorption onto Kutch clays: Influence of competing ions

The sorption of Cs+ onto raw Kutch clay (India) over a wide range of concentrations and pH levels was studied and compared with its sorption onto the well-studied FEBEX clay (Spain). The principal clay mineral in both samples is montmorillonite. Non-linear sorption isotherms were measured for both clays. The shapes of the isotherms prompted the use of a two-site exchange thermodynamic model to describe the experimental data. However, differences in the highly selective sorption sites (Type 1) were observed for the two studied clays. It was found that the presence of different cations (H+, Ca2+, Mg2+, etc.) in solution affected the sorption of Cs+. A model accounting for the competition process was developed for predicting the behavior of the raw clay in complex solutions.