ELECTROKINETIC PHENOMENA IN MICROPOROUS MEMBRANES WITH A FIXED TRANSVERSE CHARGE-DISTRIBUTION

The charged capillary model for microporous membranes has been extende d to account for a distribution of fixed charge transversal to the por e wall. The non-linearized Poisson-Boltzmann equation has been solved numerically and results obtained for an exponential charge distributio n function have been analyzed. The expressions used for computing the streaming potential and the pore conductivity arise from Poisson-Boltz mann equation together with Nernst-Planck and Navier-Stokes equations. The effect of charge displacement on streaming potential and wall pot ential is significant, especially for high bulk electrolyte concentrat ion, unlike Pore Conductivity which slightly changes with respect to t he case of charge smeared at the pore wall. The model is expected to b e useful for microporous membranes whose pore dimensions are very smal l, and also for some membrane-like biological systems. In particular, this transverse-charge model could be used in the study of electrokine tic phenomena through human Stratum Corneum, provided fixed charge den sity and ''pore'' dimensions are known.