Preparation of Graphene Oxide Nanosheets-Embedded Thin-Film Composite Reverse Osmosis Membrane with High Flux, Anti-Biofouling, and Chlorine Resistance

Abstract

Recently, a few studies reported that the coating of graphene oxide (GO) nanosheets on a thin-film composite (TFC) reverse osmosis (RO) membrane effectively enhanced chlorine resistance and anti-biofouling property. However, it turned out that the GO coating could not improve membrane water permeability because the GO coating layer interfered with water permeation. In this study, GO nanosheets were embedded in TFC RO membranes to solve such interference with water permeation. The performances of GO-embedded TFC RO membranes were evaluated in terms of chlorine resistance, anti-biofouling property, and water permeability and factors affecting such performances were investigated. Firstly, the TFC RO membrane with GO nanosheets embedded in the active layer (A-GO-TFC membrane) was fabricated via addition of the size-controlled GO nanosheets in MPD aqueous solution. The GO nanosheets embedded in active layer enhanced chlorine resistance of a membrane via shielding the active layer and forming hydrogen bonding with the active layer. In addition, the embedment of GO nanosheets increased hydrophilicity and negative zeta potential and decreased surface roughness of a membrane. As a result, the anti-biofouling property of the membrane was dramatically ameliorated. Furthermore, water permeability was significantly improved due to the high membrane hydrophilicity and low interference of dispersed GO nanosheets with the water permeation. Secondly, the TFC RO membrane with GO nanosheets embedded in both the active and support layers (AS-GO-TFC membrane) was prepared via addition of GO nanosheets in MPD and PSf solutions. The embedment of GO nanosheets in the support layer further raised the hydrophilicity, negative zeta potential, and even surface roughness due to the functional groups of GO nanosheets in both of active and support layer and high surface roughness of GO embedded support layer. In addition, the GO embedded support layer could make GO nanosheets in MPD solution disperse more evenly. Consequently, the water flux and anti-biofouling property of the AS-GO-TFC membrane were significantly enhanced compared with the A-GO-TFC membrane. The successful improvement of the membrane performances such as the water permeability, salt rejection, chlorine resistance, and anti-biofouling property by embedding GO nanosheets in both the active and support layers of the TFC membrane could be expanded to industrial RO system and various environmental engineering systems.