Preparation of superhydrophobic polyimide fibrous membranes with controllable surface structure for high efficient oil-water emulsion and heavy oil separation

Super-wetting fibrous membranes have been widely researched for the separation of oil-water mixtures and light oil-water emulsions. However, reusable oil-water separation membranes for heavy oil with high viscosity and high density have proved to be extremely challenging. Herein, superhydrophobic, flexible, and foldable polyimide (PI) nanofiber membranes for heavy oil separation were prepared by using electrospinning method combined with surface modification to build a stable nano-scale roughness on the fiber surface. The results demonstrated that the fibrous membranes modified by fumed silica and 1H, 1H, 2H, 2H-perfluorooctyl trichlorosilane(PFTS) not only had excellent mechanical robustness, but also achieved both ultra-high oil-water selectivity and separation performance. The as-prepared PI fibrous membranes showed the ultra-high gravity-driven light/oil-water emulsion separation flux of 3904.7 L m−2 h−1 and 22474.7 L m−2 h−1 with and without emulsifier stabilization, and the flux of heavy oil can reached 271.36 L m−2 h−1 under 25KPa. The mechanically robust and reusable PI fibrous membranes with high efficient oil-water emulsion and heavy oil separation performance exhibit great potential for practical applications for oily wastewater and oil spill treatment.