Thermodynamics and kinetics of ion exchange of a hybrid cation exchanger, zirconium diethylene triamine pentamethylene phosphonate

Abstract

A novel hybrid cation exchange material of the class of tetravalent metal acid salt, zirconium diethylene triamine pentamethylene phosphonate, has been synthesized by sol gel method. The material has been characterized by elemental analysis, FTIR, TGA and DSC studies, X-ray diffraction studies and SEM. Physico-chemical and ion exchange characteristics have also been determined. Chemical stability of the material has been assessed in various acids, bases and organic solvent media. The equilibrium exchange of Mg²⁺, Ca²⁺, Sr²⁺and Ba²⁺ions with the H⁺ ions contained in the ion exchanger has been studied at varying temperatures with constant ionic strength. On the basis of the exchange isotherms, various thermodynamic parameters such as equilibrium constant, standard Gibbs free energy, entropy and enthalpy and kinetic parameters such as self-diffusion coefficient, energy of activation and entropy of activation have been evaluated under the conditions favouring a particle diffusion-controlled mechanism.