ELECTRIC-FIELD INTENSIFICATION OF SURFACTANT-MEDIATED SEPARATION PROCESSES

In an electric field enhanced crossflow microfiltration study of a dou ble chain cationic surfactant (dioctadecyldimethylammonium chloride) i n water, the transient and steady state permeate flux and rejection ar e evaluated at two different temperatures which affect the morphology of the charged surfactant particles. It is found that, in the presence of the electric field, the transient permeate flux and rejection reac h steady state faster compared with the no electric field case. Steady state permeate flux and rejection enhancements due to the electric fi eld are surfactant concentration and electric field strength dependent . Evaluation of the membrane process efficiency at steady state shows the existence of different mechanisms which can be characterized by a particle flux equation due to Fickian diffusion, electric and flow fie lds. The membrane efficiency curves demonstrate the enormous increases achieved in permeate flux and rejection. The presence of the electric field also allows the filtration of dispersions with concentrations w ell above the pseudo gel concentration. These results indicate that, w ithout the electric field, only a small fraction of the membrane separ ation capacity is utilized. Electrolysis reactions taking place during electrofiltration are followed by measuring the pH and conductivity o f the permeate.