STREAMING POTENTIALS OF NUCLEPORE MEMBRANES BY THE ELECTRIC WORK METHOD

Streaming potential measurements have been carried out on NUCLEPORE po lycarbonate membranes with pore diameters between 0.015 and 1.0 mu m, equilibrated in KCl or NaCl solutions. Three types of membrane behavio r can be seen from the variation of emf with time. Concentration polar ization across the membrane is significant for a membrane with pore di ameter of 0.015 mu m. For membranes with pore diameters between 0.015 and 0.6 mu m, the emf rises rapidly towards a stable value when a pres sure difference is applied. In membranes with pore diameters between 0 .6 and 1 mu m, the high liquid velocity alters the interactions at the wall during the course of measurement, and this is reflected in a dec reasing emf with time. Some results obtained by varying pore radius an d concentration agree with previous studies. Our results, as well as r esults reported in the literature, are interpreted in terms of a new t heoretical method; the electric work method. Electric work is produced for positive liquid velocity, consistent with momentum production at the membrane wall during the measurement. A relation between the magni tude of layer where momentum transfer takes place and the streaming po tential can be applied. Momentum transfer at the membrane wall may ext end about 0.1 mu m into the pore.