Experimental estimation of equilibrium and transport properties of sulfonated cation-exchange membranes with different morphologies

Solvent uptake, hydraulic and electroosmotic permeabilities, true cation transport number, effective fixed charge concentration, and limiting current values have been determined in aqueous LiCl solutions for three commercial cation-exchange membranes with different morphologies and similar electric properties. The differences found in the equilibrium and transport properties of the membranes have been analyzed on the basis of their different structures. The experimental results show that the membrane morphology has an influence on the effect that the presence of an electrolyte has in the solvent uptake and in the liquid permeation. Differences have also been found in the polarization concentration effects, and on the loss of the membrane selectivity with the increase of the electrolyte concentration.

The figure represents the ratio between the effective fixed charge concentration and the fixed group concentration of three sulfonated cation-exchange membranes with different morphologies in LiCl aqueous solutions.Figure optionsDownload as PowerPoint slide