Forward and reverse ion-exchange kinetics for some alkali and alkaline earth metal ions on amorphous zirconium(IV) aluminophosphate

The Nernst-Planck equations are applied to study the ion-exchange kinetics on the surface of zirconium-(IV) aluminophosphate for Li+/H+, Na+/H+, K+/H+, Mg2+/H+, Ca2+/H+, and Sr2+/H+ exchanges in the forward and reverse directions under the conditions favoring particle diffusion. On the basis of these studies, various physical parameters such as the self-diffusion coefficient (D-0), the energy of activation (E-a). and the entropy of activation (Delta S*) have been determined and a correlation has been made of these parameters with the ion-exchange characteristics of the material. The study gives an insight into the ion-exchange processes going on in the exchanger phase and its potential use in metal ion separations.