Adsorption of thorium(IV) on MX-80 bentonite: Effect of pH, ionic strength and temperature

The adsorption of Th(IV) on MX-80 bentonite as a function of pH, ionic strength, Th(IV) concentration and temperature was studied by using batch technique. The results indicated that the adsorption of Th(IV) on bentonite depended on pH, ionic strength and temperature. The adsorption of Th(IV) decreased with increasing temperature, indicating that the adsorption process of Th(IV) on bentonite was exothermic. The experimental data of Th(IV) adsorption isotherms were obtained at T = 293, 303, 313, and 323K, and were analyzed with the Langmuir and Freundlich models, showing that the Langmuir model fitted the adsorption data better than the Freundlich model. Thermodynamic parameters, such as ΔHo, ΔSo, and ΔGo, were calculated from the slope and intercept of the linear plot of lnKd against 1000/T.