Removal of Cd(II) and Pb(II) complexes with glycolic acid from aqueous solutions on different ion exchangers

Abstract

The sorption of Cd(II) and Pb(II) ions from aqueous solutions on different ion exchangers was investigated by using glycolic acid (GA) as a complexing agent. Glycolic acid is useful for organic synthesis in oxidation–reduction, esterification, and long-chain polymerization. The experiments were carried out by using the following chelating ion exchangers: Purolite S-930, Purolite S-940, Purolite S-950, Diaion CR-20, and Wofatit MC-50 and the cationic ion exchangers: Purolite C-104, Lewatit CNP-80, and Lewatit SP-112. The influence of the initial concentration of Cd(II) and Pb(II) and glycolic acid, pH of the solution, and phase contact time on the sorption percentage was determined in the batch experiments. Pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data, fitted using the Langmuir and Freundlich adsorption models, were applied to describe the equilibrium isotherms and determined the isotherm constants. The Cd(II) and Pb(II) concentrations in the raffinate were determined by the AAS method.