ELECTRO-OSMOSIS OF WATER THROUGH LIQUID MEMBRANES

The experiments on hydraulic permeability, electro-osmotic velocity, streaming potential and current reported in this paper lend support to Kesting's liquid membrane hypothesis according to which when a surfactant like PVME is added to water or aqueous solutions flowing through a membrane, a surfactant layer at the interface between the membrane and the aqueous solution or water is formed which acts as a liquid membrane in series with the solid membrane. The data have revealed that the water flux through the poly(vinyl methyl ether) liquid membrane does not vary proportionally with the applied pressure difference, instead a nonproportional exponential type of relationship has been shown to describe the hydraulic permeability data. In the case of electroosmotic velocity and streaming current, however, the usual proportional relationships between fluxes and the respective driving forces have been found to be valid. The analysis for mosaic membrane model has been utilized to demonstrate that when concentration of the surfactant is half its critical micelle concentration (CMC) the area of supporting membrane covered with the liquid membrane is half the area covered at CMC. At CMC the supporting membrane is fully covered with the liquid membrane. The analysis also indicates the possibility of formation of multilayers of the liquid membrane when concentration of the surfactant exceeds its CMC value. © 1979.