Multifunctional polyacrylonitrile based nanofibrous membranes with pH-regulable surface charge for efficient separation of oil-in-water emulsions and controllable removal of dyes

Developing multifunctional nanofibrous membranes for efficient oil-water separation and dye removal remains a pressing challenge. Herein, amino and TiO2 modified polyacrylonitrile (PAN) based nanofibrous membrane with unique superhydrophilicity and underwater superoleophilicity has been successfully fabricated via integration of island-in-sea multicomponent electrospinning, vacuum filtration and dip-coating approach. The resulting reconstructed nanofibrous membrane (re-H-PPT@DAPTS) as the self-supporting membrane exhibited outstanding performances for separation of oil-in-water emulsion and controllable removal of cationic/anionic dyes. The results presented that the as-obtained re-H-PPT@DAPTS nanofibrous membrane could effectively separate various surfactant-stabilized oil-in-water emulsions under low pressure (0.01 bar) with high separation efficiency (≥99.00 %) and satisfactory flux of approximately 90.00 L m−2 h−1, maintaining good recyclability. Furthermore, the re-H-PPT@DAPTS nanofibrous membrane exhibited excellent removal efficiencies (≥99.90%) for methylene blue (MEB) at pH = 11 and methyl orange (MO) at pH = 3, even at dye concentration up to 150 mg/L. Leveraging its pH-tunable surface charge, the membrane achieved selective dye separation from cationic/anionic dye mixtures. Importantly, the re-H-PPT@DAPTS nanofibrous membrane possessed photo-induced self-cleaning and antibacterial performances, ensuring superior anti-fouling and reusable characteristics suitable for real wastewater treatment. Therefore, this novel re-H-PPT@DAPTS nanofibrous membrane is anticipated to be a promising candidate for complex wastewater treatment.