Grafting activated graphene oxide nanosheets onto ultrafiltration membranes using polydopamine to enhance antifouling properties

Graphene oxide (GO) nanosheets are negatively charged and exhibit excellent antifouling properties. However, their hydrophilicity makes it challenging for their grafting onto membrane surfaces to improve antifouling properties for long-term underwater operation. Herein, we demonstrate a versatile approach to covalently graft GO onto ultrafiltration membrane surfaces in aqueous solutions at ≈22 °C. The membrane surface is first primed using dopamine and then reacted with activated GO (aGO) containing amine-reactive esters. The aGO grafting improves the membrane surface hydrophilicity without decreasing water permeance. When the membranes are challenged with 1.0 g/L sodium alginate in a constant-flux crossflow system, the aGO grafting increases the critical flux by 20% and reduces the fouling rate by 63% compared with the pristine membrane. The modified membranes demonstrate stability for 48 h operation and interval cleanings using NaOH solutions.