Ion-exchange kinetics of Cu(II) and Zn(II) from aqueous solutions with two chelating resins

The Na form of two chelating ion exchange resins Chelex 100 (Bio-Rad) and Amberlite IRC 748, both of which have iminodiacetic acid function group, was used to exchange Cu²⁺ and Zn²⁺ from aqueous solutions. Kinetic experiments were performed at 298 K in a batch mode by varying the initial concentration of metal ions (3-9 mol/m³) and initial aqueous pH value (2.0-6.5). The kinetic data were first treated by conventional unreacted-core model and by the Fick's first law that takes into account diffusion of metal ions within resin pores. The effective diffusion coefficients of metal ions were evaluated. The kinetic data were also treated and compared by a second-order reversible reaction model based on exchange reaction equilibrium. It was shown that the rate constants for Cu²⁺ and Zn²⁺ exchange with Amberlite IRC 748 resin were larger than with Chelex 100 resin under comparable conditions.