Adsorption of Gold(III) Ions onto Chitosan and N-Carboxymethyl Chitosan: Equilibrium Studies

Abstract

The adsorption of gold(III) ions onto chitosan and N-carboxymethyl chitosan (NCMC) has been investigated. Experiments were carried out as a function of pH, agitation period, and concentration of Au³⁺ ions. It was shown that the adsorption of Au³⁺ ions occurred only at the optimum pH. Kinetic studies showed a rapid adsorption of Au³⁺ from aqueous solution. Adsorption isothermal data could be interpreted by the Langmuir equation. Langmuir constants have been determined. The experimental data of the adsorption equilibrium from Au³⁺ solutions correlated well with the Langmuir isotherm equation. The uptake of Au³⁺ on chitosan and NCMC were 30.95 mg/g of chitosan and 33.90 mg/g of NCMC. The Au³⁺ ions were readily removed from chitosan and NCMC by treatment with an aqueous EDTA solution.