Porous graphene oxide surface-coated thin-film composite membrane for simultaneously increasing permeation performance and organic-fouling migration capacities

Introduction graphene oxide (GO) onto thin film composite (TFC) membrane surface shows great potential for fouling mitigation. However, GO surface-coating decreases the membrane permeability. In this study, porous GO (PGO) with relatively complete lamellar structure at proper pore size was tailored and coated into the polyamide (PA) layer of TFC membrane via layer-by-layer method. PGO surface-coating endowed TFC membrane with an enhanced permeability without sacrificing selectivity in forward osmosis system, with up to 30% enhancement of water flux over GO surface-coated membrane. Moreover, the PGO surface-coated membrane presented high anti-fouling capacity with sodium alginate as the typical organic foulant and good stability in the long-term experiment. PGO coating increased the surface smoothness, electronegativity and hydrophilicity of PA layer. At the same time, the nanopores provided additional transport channels and shortened the average transport distance of water molecules through coating layer. Our results demonstrated that functionalization of TFC membranes with PGO surface-coating is a promising approach for the development of high-performance membrane.