Ion Exchange Resins for Trace Metal Sequestration from Water

Abstract

Abstract Ion exchange resins are employed in hydrometallurgy and environmental‐pollution control for the removal of soluble metallic species. However, ion exchange sorption is a complex phenomenon and it is difficult to predict quantitative sorption behaviour in multicomponent systems. This article summarises the detailed characterisation and sorption/desorption studies of thiol (SH) based chelating polymeric resins (thiomethyl resin and Duolite GT‐73), a Hypersol‐Macronet polymer (MN‐600) and a weakly acidic ion exchanger (C‐104E) for the removal of copper, cadmium, nickel and zinc ions from water. In order to predict the performance of these ion exchangers in actual industrial processes and to understand the mechanism of metal uptake by polymeric resins, it was desirable to model the ion exchange equilibria for these resins. In this work, the applicability of surface complexation theory for the sorption of heavy metals onto these sorbents (MN‐600, C‐104E) has been explored. The sorption of copper, nickel and zinc ions from aqueous solution on these sorbents has been studied in batch equilibrium experiments for binary, ternary and quaternary systems to determine the equilibrium parameters for modelling of ion exchange equilibria. From the experimentally determined equilibrium parameters, ion exchange equilibria have been calculated for a wide range of initial conditions. The experimental results for the Macronet polymer as well as the weakly acidic ion exchanger have been compared with the results obtained using the surface complexation model for the prediction of binary, ternary and quaternary ion exchange equilibria.