Ion Exchange Kinetics of Mg(II) from Aqueous Solutions with 732 Cation-exchange Resin

The hydrogen type sulfonic resin 732 cation-exchange resin (732-CR) was applied to exchange Mg(II) from aqueous solution. The ion exchange kinetics were studied in batch experiments at temperature range of 298-328 K and Mg(II) concentration range of 5-40 mol·m-3. The kinetic data were first treated by Nernst-Planck equation for the exchange of univalent and bivalent ions, and also treated and compared by shrinking-core model that takes into account diffusion of metal ions within resin pores. The values and relationships of diffusion coefficients of counter ions (DM and DH) and effective diffusion coefficients of magnesium ions (De) were evaluated and discussed. Other useful ion exchange kinetic parameters such as self-diffusion coefficient (D0), energy of activation (ΔEa) and entropy of activation (ΔS*) were evaluated. The results show that the ion exchange process is favored under particle diffusion control mechanism and above two models can both describe kinetics of the removal of Mg(II) from aqueous solution by 732-CR.