Exchange equilibria on anion resins

Abstract

Selectivity coefficients, free exchange energies and enthalpies between 5°C and 45°C of different anion resins with functional groups of the amino type were determined for the SO − 4/Cl − system in a range of bulk salinities lying between 6 x 10 −3 and 2.4 N The experimental results showed that the selectivity for the bivalent ion depends strongly on the basicity of the resin, the affinities of the various amino functional groups following the order primary > secondary > tertiary > quaternary. Furthermore, the affinity of every resin for the sulphate ion increases with the dilution of the aqueous phase and with the equilibrium temperature. These results are in full agreement with the theoretical forecasts, and show that in heterovalent exchange processes a fundamental role is played by the phenomena connected with the electrostatic interactions.