A model for the thermal regeneration of ion-exchange resins, Part I

Abstract

A theoretical model has been developed to describe the thermal regeneration of ion-exchange resins in the Sirotherm process^1-10 for desalting water. It assumes that the thermal effect is primarily due to the large increase that occurs in the ionization of water when the temperature is raised. The hydrogen and hydroxyl ions compete with salt for exchange sites in the resins and for that reason water, itself, acts as a regenerating acid and base.     Calculations have been made of the equilibrium conditions, column behaviour, and titration behaviour of mixtures of weak-acid and weak-base resins with aqueous solutions of 1 : 1 and 2 : 2 electrolytes, assuming the systems to obey Donnan's equilibrium relationship. There is satisfactory agreement between the calculated and observed effects of both temperature and pressure.