Temperature effects in barium sorption on natural kaolinite and chlorite-illite clays

The sorption of Ba2+ ion on natural kaolinite and chlonte-illite clays was investigated at different initial concentrations and temperatures using the radiotracer method. The sorption data were well described by Freundlich and Dubin in-Radushkevich isotherms. Ba2+ Sorption on both clays showed an exothermic behavior with DeltaHdegrees (kJ/mol) values being -7 and -5 for sorption on kaolinite and chlorite illite mixed clay, respectively. The DeltaGdegrees values indicate that the sorption was spontaneous with sorption energies corresponding to ion-exchange type sorption. X-ray diffraction studies showed that no significant change in the matrix of the clays occurred upon Ba2+ sorption.