Development of Immobilized Metal Ion Affinity Gel: Adsorption and Desorption Properties of Metal Ions Onto and From Chelating Sepharose Fast Flow Gel

Abstract

Immobilized metal ion affinity gel is a regenerable carrier used in separation technique on the basis of a reversible interaction between the gel and a specific transition metal ion as a ligand. An experimental investigation concerning the development of an immobilized metal ion affinity gel and the adsorption and desorption properties of metal ions was carried out by using a Chelating Sepharose Fast Flow gel and divalent transition metal ions of Co2+ and Ni2+. In order to characterize and predict metal ion adsorption and desorption completely, one seeks the information about the adsorption isotherms and the necessary physical parameters for adsorption and desorption along with their mechanisms. In this experimental investigation it is considered that the two –CH2COOH groups in the gel combine with metal ions stoichiometrically and the adsorption and desorption mechanisms of the metal ions onto and from the gel are theoretically analyzed on the basis of adsorption and desorption equilibriums and the dissociation equilibrium. Consequently, the model equations, which allow quantitative consideration of the adsorption and desorption mechanisms, can be derived as a function of the concentration of hydrogen ions at the outer aqueous phase. The values of adsorption effectiveness factor were calculated as 0.87 for Co2+ and 0.90 for Ni2+. Finally, the gel adsorption isotherm and the adsorption, desorption equilibriums of metal ions can be explained fairly well by these models.