Evaluation of permselectivity of a liquid anion-exchange membrane by diffusion dialysis

Abstract

The permselectivity of liquid anion-exchange membrane containing high molecular weight amines to some organic and inorganic anions was evaluated by diffusion dialysis. The relative ion exchange constant of the membrane solution was determined by a solvent extraction procedure. The apparent diffusivity of several ion pairs through a supported liquid membrane was determined by the time lag method. The permselectivity to the anions was approximately consistent with the Hofmeister anion series and it was correlated with the diffusivity of ion pairs in the membrane and the relative ion exchange constant at the membrane-solution interface. The relative ion exchange constant was found to be the dominant factor in permselectivity. The concentration profile of ion pairs in a stack of liquid membranes was linear with the distance at steady state.