Facile fabrication of superhydrophilic and underwater superoleophobic chitosan–polyvinyl alcohol-TiO₂ coated copper mesh for efficient oil/water separation

Organic–inorganic hybrid membranes are attractive material for oil/water separation. Here, a hydrophilic and oleophobic membrane was prepared by coating chitosan (CTS) and polyvinyl alcohol (PVA) on the surface of copper mesh using glutaraldehyde (GA) as crosslinking agent. After introduction of TiO₂ nanoparticles, the surface roughness of the composite film was increased and a superhydrophilicity and underwater superoleophobicity surface was obtained due to the enhancement in wettability. The as-prepared superhydrophilic membrane was characterized by SEM, FTIR, XRD, and its surface wetting behavior was measured by contact angle meter. The effect of CTS, PVA, GA, and TiO₂ on the microstructure, underwater oil contact angle, and sliding angle was comprehensively evaluated. Then, the super hydrophilic membrane was used for oil/water separation, a separation efficiency (> 99.7%) was obtained with a flux rate of 16,000 L m⁻² h⁻¹. The intrusion pressures for all tested oils that the membrane can support are above 1.0 kPa. Significantly, the super hydrophilic membrane exhibited good antiabrasion and anticorrosive properties. After repeated use for 60 times, the separating performances and average permeate fluxes showed no obvious degradation.

An organic-inorganic hybrid chitosan (CTS)–polyvinyl alcohol (PVA)-TiO₂ coated copper mesh with superhydrophilicity–underwater superoleophobicity was fabricated by one-step solution immersion method and can be used for efficient oil/water separation.