Self-cleaning nanofiber membrane for efficient oil-water separation and dye degradation

Conventional hydrophobic membranes often suffer from fouling accumulation due to the absence of effective self-cleaning mechanisms, thereby hindering their long-term operational stability and recyclability. In this study, a polyacrylonitrile (PAN)-based composite nanofiber membrane with a hierarchical micro-nano surface structure was fabricated by combining the in-situ growth of TiO 2 with an optimization of octadecyltrimethoxysilane (OTMS) coating morphology. Benefiting from the unique hierarchical morphology of micron-scale flower clusters and nano-protrusions, coupled with the synergistic effect of photocatalyst TiO 2 and the superhydrophobic layer OTMS, the resulting nanofiber membrane (PAN/TiO 2 /OTMS) exhibited outstanding dual-functional properties of superhydrophobicity (water contact angle >154°, sliding angle <5°) and photocatalytic activity (a degradation efficiency of 99 % for methylene blue within 150 min). Moreover, the PAN/TiO 2 /OTMS nanofiber membrane demonstrated favorable demulsification capability in water-in-oil emulsions, with an oil permeation flux of 2388 L m −2 ·h −1 and a water separation efficiency of 99.9 %. More importantly, owing to dual self-cleaning mechanisms of physical superhydrophobicity and chemical photocatalysis, the as-prepared PAN/TiO 2 /OTMS exhibited a favorable antifouling and regeneration performance, demonstrating the oil flux recovery above 83 % and the irreversible fouling ratio below 17 % after multiple operation cycles. This study offers a practical strategy for the rational development of advanced membranes that integrate synergistic physical and chemical self-cleaning properties.