Anti-fouling mechanism of ultrafiltration membranes modified by graphene oxide with different charged groups under simulated seawater conditions

There are positively charged Ca2+ and Mg2+, negatively charged colloids and lots of bacteria in seawater. The different surface potentials of ultrafiltration membranes may lead to different adsorption properties for contaminants in seawater when ultrafiltration membranes were applied to the pretreatment of Reverse Osmosis process. Herein, this work prepared modified ultrafiltration membranes with different surface potentials using three GO-based materials, and investigated the anti-fouling of Ca2+, Mg2+, humic acid, the anti-bacterial adhesion performance and mechanisms of modified ultrafiltration membranes under simulated seawater conditions. Results showed that the modified membranes exhibited enhanced hydrophilicity, anti-fouling performance, antibacterial property and permeability compared with the unmodified polyvinylidene fluoride membrane. Conspicuously, with the highest surface potential among all membranes, quaternized graphene oxide modified ultrafiltration membrane (QGO-M) presented the best anti-fouling property to Ca2+, Mg2+, humic acid and antibacterial property. In particular, the flux recovery rate against the simulated seawater solution containing humic acid and the surface bacteriostatic rate against salt-tolerant bacteria of QGO-M were 95.7% and 97.9%, respectively. The results can provide an important reference for the investigation of modified ultrafiltration membranes suitable for seawater filtration.