Surface Characterization and Thermodynamics of Adsorption of Pr,Nd and Er on Alumina from Aqueous Solution

The porous nature of alumina has been investigated using various techniques. The values obtained for moisture content, surface area, pore volume, average particle size and porosity were 22%, 116 m²/g, 0.76 cm³/g, 17.0±0.5 μm and 68.0%, respectively. The adsorption isotherms of Nd^III, Pr^III and Er^III on alumina from aqueous solution have been obtained at different temperatures. All these adsorption isotherms obey the Langmuir, Freundlich and Dubinin-Radushkevich isotherm equations. Thermodynamic parameters such as the free energy, entropy and enthalpy of adsorption have been computed and interpreted. It is noteworthy that the adsorption of Pr^III and Nd^III increases with decreasing temperature while the reverse is observed for Er^III.