Surface modification of polysulfone ultrafiltration membrane by oxygen plasma treatment

Oxygen plasma treatment was used to change the hydrophobic polysulfone ultrafiltration membrane to the hydrophilic membrane. The contact angle of water decreased with increasing the oxygen plasma treated time of polysulfone membrane and was saturated with 20 s of oxygen plasma treated time. Functional groups introduced by oxygen plasma treatment were examined using X-ray photoelectron spectroscopy (XPS) and zeta potential of oxygen plasma treated polysulfone membrane was measured using electrophoretic light scattering (ELS) spectrometer. O/C ratio increased from 33 to 50% and isoelectric point (IEP) of membrane surface increased from pH 3 to 4.5. For oxygen plasma treated polysulfone membrane, the flow rates of pure water and gelatin solution increased at all pH range and plasma treated membranes showed less fouling at membrane surface. The mechanisms of reduced fouling and improved cleaning efficiency of oxygen plasma treated polysulfone membrane were also studied.