Electrochemical characterization of polysulfone membranes with different valence salt solutions

Abstract

Membrane potentials of polysulfonated cation-exchange (SA 3S and SA 3T) membranes for KCl, NaCl, LiCl, CaCl 2 and FeCl 3 solutions using Ag/AgCl electrodes were measured. The measurements were carried out for, KCl|SA 3S or SA 3T|MCl, (M:K, Na, Li, Cu and Fe) systems. The concentration of salt solution (KCl) was kept constant in one side of the cell, C 1, at 1×10 −2 M and was changed in the other side of the cell, C 2, from 1×10 −4 to 2 M. The alteration graphs were drawn in order to find the potential values of membranes for ln (C 1/C 2) ratio changes. Using the values, the effective fixed charge density in membrane ( C x ), the average value of transport numbers ( t ±), and partition coefficients ( K ±) in a polysulfonated cation-exchange membrane for different valence ions were determined. Using the Donnan equation and the Teorrel–Meyer–Sievers theory, membrane diffusion potentials and Donnan potentials were calculated both theoretically and experimentally.