Hierarchically tunable structure of polystyrene-based microfiber membranes for separation and selective adsorption of oil-water

Separation and selective adsorption of oil–water are widely involved in the industrial and marine oil pollution removal. Among the advanced materials, microfiber membrane is a kind of desirable ones. Even so, the effective, low-cost and green fabrication as well as precise structure control of the microfiber and membrane still remains challenging. Herein, a facile approach was proposed to fabricate hierarchically structural membrane with excellent hydrophobicity-lipophilicity via one-step electrospinning. Cellulose acetate (CA), silica nanoparticles (SiO2 NPs) and hydrophobic silica nanoparticles (HSiO2 NPs) were added into polystyrene (PS) solution, which was electrospun into PS-based microfiber membrane with improved fiber porosity and surface roughness but reduced surface energy. The tunable inner-fiber porosity and inter-fiber pore size distribution of PS-CA microfiber membrane were optimized and adopted for oil–water separation with a flux as high as 11,460 L·m−2·h−1 for petroleum ether, while the PS-CA-HSiO2 microfiber membrane was ultra-hydrophobic and promising for oil adsorption. Moreover, five-layer structured membranes were developed by stacking the PS-CA and PS-CA-SiO2 (or PS-CA-HSiO2) microfiber sub-membranes alternately, to further enhance their oil adsorption performance (>160 g/g for high viscosity oils). The current study offered a strategy for the bottom-to-top design of microfiber composite membranes for separation and selective adsorption of oil–water.