Effects of Graphene Oxide Size on PES ‎Ultrafiltration Hydrophilicity and Pure ‎Water Flux

In this study, the effects of graphene oxide (GO) size on the structure and performance of polyethersulfone/graphene oxide nanocomposite ultrafiltration membrane (prepared via phase inversion method) were studied. Graphene oxide was synthesized by Hummers method and was divided into two parts with different sizes (80 nm and 110 nm) by means of centrifugation (10000 rpm). Synthesized GO was characterized by FESEM, TEM, Raman spectroscopy, FTIR, XRD and DLS. Prepared membranes were characterized by FESEM, AFM, contact angle and pure water permeation flux. Interestingly, decrease in PWP permeance was observed with an increase in the concentration of smaller GO in the membrane, while the trend was reversed by the addition of the larger GO. As a result, the maximum PWP permeance of 21 kg/m2</sup> h bar was achieved when the smaller GO concentration was 0.1 wt.% while 23 kg/m2</sup> h bar was achieved when the larger GO concentration was 1 wt.%.  This opposite trend is ascribed to the readiness of smaller GO nanosheets to aggregate. The antifouling capacity of nanocomposite membranes was found to be higher than the pristine PES membrane.