Thermodynamics of Ion-Exchange Reaction in Predicting the Ionic Selectivity of Auchlite ARA-9366 and Auchlite A-378 Anion Exchange Resins

The paper deals with predicting the iodide ion selectivity of nuclear and non-nuclear grade anion exchange resins. The ionic selectivity prediction was made on the basis of thermodynamic data of Clˉ/I ˉ ion exchange reaction. It was observed that with rise in temperature from 30.0 °C to 45.0 °C, the equilibrium constant (K) values were observed to decreases from 59.77x10^-2 to 23.77x10^-2 for Auchlite ARA-9366 resins and from 9.01x10^-2 to 4.05x10^-2 for Auchlite A-378 resins. The decrease in K values with rise in temperature, indicate exothermic ion exchange reactions having enthalpy values of -47.87 and -39.51 kJ/mol respectively. The high K and low enthalpy values obtained for Auchlite ARA-9366 resins indicate their greater selectivity for the iodide ions in the solution as compared to Auchlite A-378 resins, when both the resins are present in chloride form.