SORPTION OF CESIUM ON MONTMORILLONITE AND EFFECTS OF SALT CONCENTRATION

The sorption behavior of cesium on montmorillonite type clay was studi ed by using radioactivity measurements. Concentrations of Cs+ ions ran ged from 10(-6) to 10(-2) M. Cesium retention reduced with increasing salt concentration which was varied between 10(-4) and 10(-1) M. Selec tivity coefficients KCs-Na for the exchange between Cs and Na were cal culated for different equivalent fractions of Cs on the solid phase. U sing the KCs-Na values, free energy change was found to be 7.8 kJ/mol. The data could be fitted to a Freundlich isotherm, and empirical Freu ndlich parameters enabled the generation of a site distribution functi on. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm, a mean energy of sorption of 8.6 kJ/mole was calculated which correspond s to the energy of ion exchange reactions. The values of energy change s calculated by using two different methods were in good agreement.