Adsorption Kinetics and Isotherms for the Removal of Zinc Ions from Aqueous Solutions by an Ion-Exchange Resin

Abstract

The capacity of ion exchange resins, Dowex HCR-S, for removal of Zinc from aqueous solution was investigated under different conditions such as initial solution pHs, stirring speeds, temperatures, initial concentrations and resin dosages. Adsorption equilibrium isotherms were analyzed by Langmuir, Freundlich, Temkin, Elovich, Khan, Sips, Toth, Radke-Praunstrzki, Koble-Corrigan, models. Khan model was found to show the best fit for experimental data. The experimental kinetic data were analyzed using the first-order, second-order, Elovich and intra-particle kinetic models and the second-order kinetic model described the ion exchange kinetics accurately for Zn (II) ions. Thermodynamic activation parameters such as Delta G*, Delta S* and Delta H* were also calculated.