Recent development of special wettability filtration membrane for selective oil/water separation applications: A review

The separation of oil/water mixture or emulsion is an important field, which is of significance to solve the problem of oily wastewater. Many oil/water separation methods and techniques have been widely studied. Due to its convenience of operation and efficiency, membrane separation has been known as the most promising method for the effective treatment of wastewater. Among various materials for the membrane preparation, the research of polymer-based membrane has become the focus of the research. In this review, the research progress of membranes on liquid filtration was systematically reviewed from the principle of wetting and filtration mechanism, to selective wettability membranes, including conventional wetting membranes (superhydrophobic membranes and hydrophilic-underwater oleophobic membranes), special wetting membranes (stimulus response membranes and asymmetric wetting Janus membranes) and other multi-functional composite membranes. Finally, the main challenges that need to be addressed and future research directions of filtration membranes are briefly discussed, which can provide new ideas for the structural design of liquid filtration materials for light industrial manufacturing, wastewater treatment, etc., as well as a better understanding of the limitations of this promising research area.