Physicochemical Principles of Testing Ion-Exchange Membranes

N. P. Gnusin , N. P. Berezina , O. A. Demina , N. A. Kononenko
Российский электрохимический журнал
Abstract / Full Text

The results of investigations into concentration dependences of a wide number of transport characteristics pertinent to ion-exchange membranes of different production are generalized. A series of experimentalprocedures for measuring electrotransport characteristics of membrane materials under comparable experimental conditions is suggested. The nature of concentration dependences of electroconductivity, diffusive and electroosmotic permeability, and potentiometric transport numbers in a wide range of concentrations of equilibriumNaCl solutions is discussed. It is suggested that three concentration zones, which correspond to certain physicochemical conditions of the NaCl solution and membrane, be singled out in order to characterize changes inthe electrotransport properties. All the membrane properties studied are found to be controlled by the contentand state of water in swollen samples that represent phase-separated conducting systems. Parameters of thetwo-phase model, which allow one to elucidate the reasons for distinctions in electrotransport of ions and waterin ion-exchange membranes, are reported and compared. The research performed lays a physicochemical foundation for testing membranes with the aid of the approaches that are described in the paper.