Thermal studies on the dehydration of polystyrene—divnylbenzene-type ion exchangers

Abstract

Thermal studies on fully swollen polystyrene—divinylbenzene-type resins variously cross-linked Dowex 50W (Li +) resisn adn Dowex 1-X8 (Cl −, Br −, I − and NO − 3 resin forms have been carried out. Thermogarvimetric analysis of the resisn showed that apparently all of the water was lost in one step between 300 and 383°K. Isothermal kinetic data for the resins best fitted the contracting envelope equations. Nearly 70% of the total water in the resisn, corresponding to the osmotic water in the resin phase, was lost at a constant rate. The activation energies for this part of the dehydration for Li + and NO − 3 resins were greater and those for Cl −, Br − and I − resins were smaller than the enthalphy of evaporatin of normal water. This indicates a more ordered state of water in Li + and NO − 3 resins adn more disordered state in Cl −, Br − and I − resins than in normal water. These results are discussed in terms of a generally accepted model for the structure of aqueous electrolyte solutions.