Anti-fouling TiO2 nanowires membrane for oil/water separation: Synergetic effects of wettability and pore size.

Abstract TiO 2 nanowires (NWs) membranes with varied wettability ranging from superhydrophilic to superhydrophobic have been facile fabricated via dip-coating for oil/water separation. Incorporating TiO 2 NWs results in the increase of roughness and the formed hierarchical structure from TiO 2 NWs micro-aggregations enlarges the wettability. Separation efficiency and permission flux of the as-prepared membranes increase first and decrease with the increment of TiO 2 NWs. These superhydrophilic/hydrophilic membranes eliminate water from oil/water mixtures and the separation efficiency declines with the increasing water contact angle until the membrane lose the oil/water separation property at around 90°. Membranes with water contact angle of 90–100° cannot separate oil/water mixtures while membranes with water contact angle larger than 120° become oil-remove type with separation efficiency around ~ 99% and high permission flux. The study illustrates that relatively large pore size (~ 15 µm) attributes to the high separation efficiency and permission flux. The synergetic effects of wettability and pore size indicate that surface wettability is critical for efficient oil/water separation. Both hydrophilic and superhydrophilic membranes show high separation efficiency and outstanding anti-fouling performances after long term oil/water separation. Graphical abstract fx1 Highlights • Membrane with varying wettability has been fabricated via coating small amount of TiO 2 nanowires; • Micro/nano hierarchical structure is formed via coating TiO 2 nanowires; • Synergetic effects of wettability and pore size on oil/water separation has been investigated; • As-prepared membrane shows outstanding anti-fouling performance after long term operation. [ABSTRACT FROM AUTHOR]