Zeta-potential of fouled thin film composite membrane

The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It w as confirmed that this method could be effectively applied to analyze the f ouling of such membranes. It is known that the water flux of membranes drastically decreases as a res ult of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SE M, EDX and FT-IR, their presence could be clarified by the profile measurem ents of the surface zeta-potential. The profiles of the membrane surface ze ta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring me thod of surface zeta-potentials allowed us to analyze a very small amount o f fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film co mposite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that th is method is easy and effective for the reverse osmosis membrane surface an alysis of adsorbed materials such as surfactants.