Membrane surface modification with TiO2–graphene oxide for enhanced photocatalytic performance

• Polysulfone membranes were modified with TiO2 and graphene oxide (GO).
• TiO2–GO enabled membrane photocatalytic activities under both UV and sunlight.
• Methylene-blue removal was improved due to photodegradation.
• Membrane flux was increased as a result of photo-enhanced hydrophilicity.

Taking advantage of the unique property of graphene oxide (GO) nanomaterials in expanding the light-response range of TiO2, we modified the surface of water filtration membranes with TiO2–GO to enhance their photocatalytic activities under both UV and sunlight irradiations. A layer-by-layer approach was employed to sequentially deposit TiO2 nanoparticles and GO nanosheets on a polysulfone base membrane, with GO partially reduced via ethanol/UV post-treatment. The grafting of TiO2–GO on the membrane surface was confirmed through the analysis of QCM-D measurements and SEM images. We then studied the photocatalytic properties of the surface-modified membranes in both batch and filtration experiments using methylene blue (MB) as a representative organic contaminant. Compared with polysulfone membranes surface-modified with TiO2 and GO, respectively, the TiO2–GO membrane exhibited significantly improved MB photodegradation kinetics under UV (about 60–80% faster) and sunlight (3–4 times faster). Besides, the membrane flux increased as a result of the photo-enhanced hydrophilicity and contaminant degradation. Therefore, surface modification by TiO2–GO grafting provides a very promising route to the fabrication of high-performance photocatalytic membranes for sustainable water treatment.