Kinetics and equilibrium studies for the removal of nickel and zinc from aqueous solutions by ion exchange resins

Removal of heavy metals from wastewater is obligatory in order to avoid water pollution. In the present study, performance of Dowex HCR S/S cation exchange resin was evaluated for removal of nickel and zinc from aqueous solutions. Batch shaking adsorption experiments were performed in order to examine the effects of pH, dosage of resin and contact time on removal process. It was observed that more than 98% removal efficiency was achieved under optimal conditions for nickel and zinc. The experimental equilibrium data were tested for the Langmuir, Freundlich and Temkin isotherms. Correlation coefficients indicate the following order to fit isotherms: Langmuir > Freundlich > Temkin for both nickel and zinc ions. Pseudo-first- and -second-order kinetic models were used for describing kinetic data. It was determined that removal of Ni2+ and Zn2+ was well-fitted by second-order reaction kinetic. Furthermore, separation factors and distribution coefficients of nickel and zinc for Dowex HCR S/S were calculated.