Zeta Potential of Reverse Osmosis Membranes: Implications for MembranePerformance

摘要

This report, presents data and analysis of the streaming potentials of fourdifferent types of membranes measured using an electrokinetic analyzer. Three reverse osmosis membranes and one thin film composite nanofiltration membrane were analyzed. The reverse osmosis membranes consisted of an asymmetric cellulose acetate blend, a fully aromatic polyamide thin-film composite, and a thin film composite with enhanced rejection. Zeta potentials were calculated from the measured streaming potential using the Helmholtz-Smoluchowski equation. Results show that all membranes display an iso-electric point at an acidic pH; the zeta potentials is megatively charged at pH values above the iso-electric point and is positively charges at lower pH. Measurements were also made in the presence of divalent ions and humic substances.