Ion Exchange Behaviors of Ca(II) and Mg(II) on Lewatit MonoPlus TP 207 and TP 208 Chelating Resins

Abstract

The protonation process, the adsorption equilibrium process, the adsorption isotherms and the adsorption kinetics of adsorbing Ca(II) and Mg(II) onto Lewatit MonoPlus TP 207 and TP 208 chelating resins were studied using the pH titration method and batch experimental method. By omitting the ionic charges, first protonation constants, second protonation constants and equilibrium constants were determined. The adsorption behaviors were found to be dependent on contact time, pH, temperature and initial concentrations. The experimental adsorption isotherms were fitted using both the Freundlich and Langmuir models. The adsorption kinetics was described by means of the pseudo-first-order and pseudo-second-order kinetic models. The adsorption mechanism was found to involve intra-particle diffusion and film diffusion, where both were found to be the rate control steps.