Robust functional Janus nanofibrous membranes for efficient harsh environmental air filtration and oil/water separation

The massive discharge of industrial waste gas and oily wastewater seriously harms the ecological environment and human health. It still remains a tremendous challenge for researchers to develop robust functional materials to control air pollution and purify oily wastewater in actual harsh environments. Herein, a polyacrylonitrile (PAN)@TiO2/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)@SiO2 nanofibrous (PTPSNF) Janus membrane was successfully prepared by sequential electrospinning strategy. Due to its unique bi-layer structure and synergistic effect of multiple components, the composite filter could overcome the trade-off effect of high filtration efficiency and low air resistance and realized filtration efficiency of 99.7 % (PM0.3 removal) with a pressure drop of 27 Pa. The combination of the hygroscopic PAN@TiO2 layer and the self-cleaning PVDF-HFP@SiO2 layer endowed the Janus filter obvious advantage in the field of personal protection. Meanwhile, the PTPSNF membranes still remained excellent air filtration performance after strong acid/alkali treatments. Furthermore, due to its asymmetric wettability, the PTPSNF Janus membranes emerged switchable oil/water separation ability, which could efficiently separate different oil/water mixtures and emulsions with high flux and separation efficiency. Therefore, the robust functional Janus nanofibrous filter offers fascinating application prospects in harsh environmental air filtration and oil/water separation.

Automated summary

Researchers have successfully developed a robust functional Janus nanofibrous filter that can control air pollution and purify oily wastewater in harsh environments. The filter, with its unique bi-layer structure and synergistic effect of multiple components, has high filtration efficiency and low air resistance. It also offers significant advantages in personal protection and retains excellent performance even after strong acid/alkali treatments. Moreover, the filter exhibits switchable oil/water separation ability, efficiently separating different oil/water mixtures and emulsions.