The hyperfiltration streaming potential as a tool in the characterization of polyelectrolyte membranes

A phenomenological expression for the hyperfiltration streaming potential is presented and discussed in the light of recent model calculations. Criteria for membrane homogeneity are defined utilizing the equivalent pore radius calculated from the electroosmotic coefficient, and the hydraulic permeability. Hyperfiltration streaming potential and water flow data for collodion polyvinylamine membranes are compared to electroosmotic and osmotic results for the same membrane. The homogeneity criteria are used to show that at one atmosphere the membrane contains parallel paths for water and ion flow, while at elevated pressure only a single path exists for both species.