Electroviscous effects, streaming potential, and zeta potential in polycarbonate track-etched membranes

Electroviscous effects and streaming potentials were measured for various track-etched ultrafiltration and microfiltration membranes at a number of salt concentrations, using both LiCl and KCl electrolytes. A calculation program was developed that calculates zeta potentials from this experimental data, using electrokinetic flow theory and a numerical solution of the Poisson–Boltzmann equation. It was demonstrated, both experimentally and by calculation, that the electroviscous effect for negatively charged membranes is larger when employing LiCl solutions than when employing KCl solutions. This effect is absent for positively charged membranes and can thus be used for determination of the sign of the membrane charge.