Rational design of electrospun nanofibrous materials for oil/water emulsion separation

The frequent oil spill accidents and ever-increasing oily wastewater discharged from our daily life and industries greatly threaten the ecological system as well as human health and cause heavy economic loss. To address this problem, developing advanced separation materials towards efficient oil/water emulsion separation is a critical way and has currently risen as a research focus. Electrospun nanofibrous materials with tunable wettability, controllable pore structure, diverse dimensions, and good connectivity hold great promise for meeting the requirements of emulsion separation applications. Herein, we present a comprehensive overview on the recent research regarding the design and fabrication of electrospun nanofibrous materials with special wettability and optimized porous structure for emulsion separation. We firstly introduce the emulsion separation mechanism, followed by the design principles of nanofibrous filtration materials. We subsequently discuss the preparation of electrospun nanofibrous materials beginning with selective wettability tunability (i.e., hydrophobic-oleophilic, hydrophilic-oleophobic, and switchable properties) and porous structure optimization (i.e., 2D and 3D porous structures). Based on the dimensions, nanofibrous materials can be categorized into nanofibrous membranes and nanofibrous aerogels. For each type, representative studies will be highlighted, focusing on the relationship between the synergy of the selective wettability and porous structure and emulsion separation performance. Finally, the existing challenges and future perspectives in the burgeoning field are provided.