CONCENTRATION POLARIZATION IN POLYELECTROLYTE-ENHANCED ULTRAFILTRATION

Polyelectrolyte-enhanced ultrafiltration (PEUF) is a new method of removing ions from water. In PEUF, a polyelectrolyte of opposite charge to the target ion is added to solution and the target ion binds to the polymer. The polyelectrolyte is then removed from the water by ultrafiltration. The resulting permeate solutions are quite pure, with measured rejections in excess of 99%. In this work, a solution containing copper was treated using PEUF with poly (styrene sulfonate) as the anionic polyelectrolyte over a wide range of polymer concentrations. As the retentate becomes more concentrated in polyelectrolyte, the rejection decreases and the flux decreases. However, even with concentrated retentate solutions, the rejections remain high (96% was the lowest rejection observed here). Fluxes only decline sharply when the concentration in the retentate is quite high. Hence, classical concentration polarization behavior is observed in PEUF, but it is not severe in the operating range of practical importance, indicating the promise of PEUF as an industrial separation process. © 1990.