Ultrafiltration Membranes with Structure-Optimized Graphene-Oxide Coatings for Antifouling Oil/Water Separation

Fouling of ultrafiltration (UF) membranes in oil/water separation is a long-standing issue and a major economic barrier to their use in a broad range of applications. Currently reported membranes typically show severe fouling, resulting from the strong oil adhesion on the membrane surface and/or oil penetration inside the membranes. This greatly degrades their performance and shortens service lifetime. Here, the use of graphene oxide (GO) as a novel coating material for the fabrication of fully recoverable, UF membranes with desired hierarchical surface roughness is accomplished by a facile vacuum filtration method for antifouling oil/water separation. The combination of ultrathin, "water-locking" GO coatings with the optimized hierarchical surface roughness, provided by the inherent roughness of the porous supports and the corrugation of the GO coatings, minimizes underwater oil adhesion on the membrane surface. Cyclic membrane performance evaluation tests revealed approximately 100% membrane recovery by facile surface water flushing, establishing their excellent easy-to-recover capability. The novel GO functional coatings with optimized hierarchical structures may have broad applications in oil-polluted environments.