Influence of the Membrane Pore Conductance on Tangential Streaming Potential

Abstract

Tangential streaming potential technique is an attractive way to characterize the electrokinetic properties of various kinds of materials such as films or flat membranes with a dense or a porous structure. However, the interpretation of data in terms of zeta potential is usually carried out by doing the implicit assumption of nonconducting substrates. In the present paper, we investigate the electrokinetic properties of a commercial ultrafiltration membrane, the porous structure of which affects the streaming potential because streaming and conduction currents involved in the streaming potential process do not flow through identical paths (the streaming current flows only through the slit channel formed by the two membrane samples facing each other whereas a non-negligible part of the conduction current is likely to flow through the membrane pores filled with electrolyte solution). The correct zeta potential value is determined from an extrapolation method for which a set of measurements with various channel heights is required. A very good agreement is obtained with zeta potential values deduced from consecutive streaming potential and total conductance measurements (referred in the text as the direct method). The ratio of the correct zeta potential to the apparent one (given by Helmholtz-Smoluchowski equation) is dependent on the pH which suggests a non-negligible contribution of surface conductance within the membrane pores.

Evaluation of the steric, electric, and dielectric exclusion model on the basis of salt rejection rate and membrane potential measurements

“…3. As can be seen, the AFC 30 membrane is found to be negatively charged, which is in agreement with reported studies dealing with polyamide membranes [24,[64][65][66]. The effective volume charge density shows an increase (in absolute value) with increasing salt concentration (diluted side concentration).…”

Surface modification of phenolphthalein poly(ether sulfone) ultrafiltration membranes by blending with acrylonitrile-based copolymer containing ionic groups for imparting surface electrical properties

“…A self-made setup which is similar to that described in Refs. [14,15] was employed to determine streaming potentials. The membrane samples were placed above and below a PTFE spacer (0.2 mm in thickness) with the membrane skin-layer facing the flow channel (170 × 10 mm).…”

Charge properties of membranes modified by multilayer polyelectrolyte adsorption

“…The tangential streaming potential cell and the exact measuring procedure can be found elsewhere [43,44]. In short, this apparatus measures the electrical potential difference (i.e., the streaming potential) generated by the imposed movement of an electrolyte solution through a slit channel formed by clamping together two identical flat membranes separated by a spacer.…”