Dynamics of ion-exchange involving multivalent cations

In a cation exchange process involving multivalent ions, diffusion rates within the resin particle are lower due to strong adsorption of ions on the fixed sites of the resin. Therefore, dissociation of the fixed sites is reduced. An ion exchange model applied to quantify adsorption characteristics of multivalent ions and experimentally verified in batch experiments using H+-Sr2+ exchange with Cl- as the coion and Dowex 50WX8 as the resin is presented. From least squares estimates, value of fσ (fraction of the total fixed sites in dissociated form) was not affected by the resin loading, type of ion pairs used and the direction of exchange and lower value of fσ showed high affinity of bivalent cation for the fixed sites.