Surface engineering of filter membranes with hydrogels for oil-in-water emulsion separation

Separating emulsified oil from wastewater is urgent from both environmental and economic perspectives. Membrane separation has been considered as an efficient technique for handling these emulsified oils. However, membranes often suffer from serious fouling issue due to the adhesion of oil droplet on membrane surface. Owing to the strong water affinity, hydration ability, and anti-oil-fouling property of hydrogels, surface engineering of filter membranes with hydrogel has become an effective way to solve the fouling issue for highly efficient oil-in-water emulsion separation. This review provides an extensive summary and analyses on the progress of this topic. The principles for designing hydrogels with outstanding anti-oil-fouling property are firstly introduced. Then, surface engineering strategies for constructing hydrogel on filter membranes toward oil-in-water emulsion separation are highlighted. Finally, the challenges and outlook for the future of this field are discussed.