Electrostatic assembly of superwetting porous nanofibrous membrane toward oil-in-water microemulsion separation

Abstract Creating a lotus-leaf-structured membrane surface with nano/microstructures plays a key role in the development of functional membranes for oil/water separation; however, fabrication of such membranes with uniform and compact nano/microstructures via an efficient and facile method have demonstrated to be challenging. Herein, a superwetting nanofibrous membrane with strong corrosive resistance was prepared via co-electrospinning of polyacrylonitrile/sulfonated polyethersulfone nanofibrous membrane (PAN/SPES NFM), amination of PAN and subsequent electrostatic assembly of lotus-leaf-structure by binding the negatively charged silica nanoparticles (SiO2 NPs). Benefiting from the changes in pore size distribution and surface structure of nanofibrous membrane, the optimal membrane is endowed with an intriguing superhydrophilicity of 0°, an underwater superoleophobicity of 161°, and an outstanding oil proof pressure of 95.5 kPa. These fantastic features inspired the membrane to effectively separate the surfactant-stabilized oil-in-water microemulsion with a high water flux of 1852 ± 158 L m−2 h−1 and a high separation efficiency of 99.6% when a vacuum driven pressure of 10 kPa was applied. The layer-by-layer assembly method utilized in the construction of membrane roughness is expected to be applicable to a wide range of other selective wetting separation fields.