A study on the performance of self-cleaning oil-water separation membrane formed by various TiO₂ nanostructures

The introduction of efficient self-cleaning oil-water separation membrane has been regarded as an important component due to the daily production of oily wastewater. TiO₂ materials have been the most promising candidate for oil-water separation membranes due to its intrinsic superhydrophilic and underwater superoleophobic properties. However, its performance is affected by its different forms of nanostructures. In this work, various TiO₂ membranes formed by different nanostructures including 1D TiO₂ nanotube, 1D TiO₂ nanowire and 3D nanosheet-decorated TiO₂ nanowire hierarchical structure were synthesized and compared. The oil-water separation results showed that the three membrane portrayed excellent oil-water separation ability due to the formation of water layers represented by their high water capture percentage (WCP). Studies from the self-cleaning experiment indicated that TSW (3D nanosheet-decorated TiO₂ nanowire) membrane has the shortest time to self clean the oleic acid accumulated on its surface and simultaneously recovers its superhydrophilicity property. In addition, the results for photodegradation activity showed that 3D nanosheet-decorated TiO₂ nanowire has the highest photodegradation efficiency amongst the investigated TiO₂ nanostructures to eliminate intermediate organic compounds. This is attributed to its high light harvesting capacity resulting from the multiple reflections of incident light and superior electron collection properties due to the hierarchical structure. In sum, this study paves way for enhancing oil-water separation performance of other photocatalysts through the modification of its nanostructure.