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

Abstract

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.