UV-induced self-cleanable TiO2/nanocellulose membrane for selective separation of oil/water emulsion

Emulsified oily wastewater threated to human health seriously, and traditional technologies are unable to separate the emulsion for the small size of oil droplets. Membranes with special wettability are considered as an efficient way for oil/water emulsions separation, but challenges remain in terms of high material costs, complex processing, and easy to be fouled. Herein, novel self-cleanable membranes composed of nanocellulose and TiO2 nanoparticles were developed through a facile and sustainable vacuum-assisted filtration process. TiO2 nanoparticles in situ generated on the surface of tunicate cellulose nanocrystals (TCNC), a kind of nanocellulose, by hydrolysis of titanium oxysulfate. The prepared nanocomposite membrane showed hierarchical architecture, high roughness, superhydrophilicity and underwater oleophobicity. After UV-light irradiation, the resulting membrane exhibited improved underwater oil contact angles and water fluxes, beneficial for the selective oil/water emulsions separation. Importantly, the TiO2/nanocellulose membrane could rapidly degrade contaminant (oleic acid) under UV-light irradiation, suggesting excellent self-cleaning property. This works provided a facile strategy for development of self-cleanable membrane from nanocellulose for oil/water emulsion separation.