Sorption of rare-earth erbium from aqueous solution onto sol-gel-derived zirconia

Zirconia powder was synthesized via sol gel method and used for erbium sorption. The adsorption is strongly dependent on pH of the medium where the removal efficiency increases as the pH turns to alkaline range. The process was very fast initially and maximum adsorption was attained within 60 min of contact. Pseudo-second-order model and homogeneous particle diffusion model (HPDM) was found to be the best to correlate the diffusion of erbium into zirconia particles. Adsorption thermodynamic parameters were calculated. Erbium adsorption is an endothermic (ΔH > 0) and good affinity of erbium ions towards the zirconia (ΔS > 0).