Nitrogen–doped GO/TiO2 nanocomposite ultrafiltration membranes for improved photocatalytic performance

Integration of photocatalysis with membrane processes is a promising and ideal alternative to reduce the membrane fouling and improve membrane properties. In our study, a novel photocatalytic membrane incorporating nitrogen-doped graphene/TiO2 (NRGT) nanocomposites has been successfully fabricated via a non-solvent-induced phase-separation method, in which the NRGT nanocomposites could lead to enhanced photocatalytic performance and endow the hybrid membrane with superior anti-fouling properties under both UV and sunlight. Compared with the polysulfone (PSF) membranes made with graphene oxide (GO), TiO2 and graphene/TiO2 (RGT), the NRGT-PSF membrane exhibited higher photodecomposition efficiency towards methylene blue (MB) solution under UV light (improved approximately 20–50%) and sunlight (improved approximately 30–80%). The MB rejection and permeation of the NRGT-PSF membrane are also preferable over other control samples due to the improved hydrophilicity, smoother surface and sequential photodegradation of foulants. In addition, the higher flux recovery ratio and fouling resistance parameters of the membranes during the anti-fouling experiment demonstrated that the NRGT-PSF membrane could regain higher water flux after fouling and thus present better fouling resistance. Hence, the NRGT-PSF membranes would have great potential as the next generation of high-performance photocatalytic membranes for water purification applications in the future.