Hydropilically Modification Of Polymer Membrane With Graphene Oxide

Membrane Bioreactor (MBR) has been widely used within wastewater treatment and reuse field for its outstanding advantages. However, the promotion of MBR has been drawn back by membrane fouling, which increased membrane resisitance and reduces flux, so more aeration and frequent cleaning was needed. Membrane fouling increased energy consumption and reduced membrane life, leading to more cost to the sewage treatment. Therefore, it is of great significance to develop anti-fouling and high flux membrane.In this study, a new material-graphene oxide(GO) was used as modifier to make PVDF membrane and non-woven polypropylene membrane(NWF) gain more hydrophilicity and permeability by surface modification.Graphite oxide was prepared with improved Hummers method, then treated by ultrasound and dispersed into deionized water and ethanol respectively. The dispersion was then used to modificate the membranes with inkjet printing and direct immersion method.(1) PVDF membrane surface cannot be wetted effectively by GO water dispersion because of different polarity when direct immersion modification method was used, while inkjet printing method could be successful to make the dispersion distributed on the membrane evenly. GO could improve the hydrophilicity of PVDF membrane surface obviously, which decreased the static cantact angle from76.0°to21.9°with a71.2%drop. The hydrophilicity of the membrane increased with growing printing times, and when the membrane was printed more than9times, its hydrophilicity was no longer changed. On the other hand, pure water flux of the modified membrane declined rapidly with the growing printing times. Pure water almost could not get through the membrane when it was printed more than3times. A5-minute ultrasound treatment could make the GO get off the membrane surface. Furthermore, DMAc could also increase the membrane hydrophilicity while it did not influence the stability of GO on membrane surface.(2) GO could be distributed evenly on the membrane by both inkjet printing and direct immersion method, among which the former one could only make GO exisit within the fiber gap on surface part of the membrane, while the latter one could distribute GO in the depths of NWF fiber gap. The static contact angle of modified membrane was not improved obviously, but the membtane’s pure water flux increased significantly. Printing20times increased the membrane flux by55.9%, while the immersion method could make the flux improved by177.5%.