Ce3+ adsorption on hydrated MnO2

The adsorption of Ce³⁺ on hydrated manganese dioxide (HMD) was studied as a function of concentration, temperature and pH of the cerium solution labelled with¹⁴¹Ce. The steady state values of cerium adsorption at various concentrations fit well with the classical Freundlich isotherm. The effect of temperature on equilibrium adsorption values was utilized to determine the change in the standard enthalpy ΔH ^o of the cerium uptake process and its value (ΔH ^o=10.57) indicates that the uptake process proceeds via ion exchange.¹⁴¹Ce desorption studies, from HMD in water, HCl and unlabelled CeCl₃ solution, confirmed the ion exchange nature of the cerium uptake process as well as its reversibility.