THERMODYNAMICS OF ADSORPTION OF CERIUM ON LEAD DIOXIDE

Adsorption of cerium on lead dioxide from aqueous solutions has been s tudied as a function of shaking time, amount of adsorbent, pH, concent ration of the adsorbate and temperature. The adsorption process is end othermic and the distribution coefficient (K-D) increases with increas ing temperature. The data fit very well the Langmuir, Freundlich, and Dubinin-Raduskevich Isotherms and their corresponding constants were c alculated. Delta H degrees and Delta S degrees were calculated from th e slope and intercept of plots of lnK(D) vs. 1/T. Delta G degrees valu es decreases with increasing temperature, showing that the adsorption of Ce(III) is more favorable at high temperature. The endothermacity o f the adsorption process is discussed.