Photothermal-catalytic double-mode self-cleaning hydrogel based polymeric nanofiber membrane reinforced by core@double-shell bismuth-rich nanohybrid for rapid emulsified oily wastewater purification

The practical application of hydrogel-based polymer membranes in separating emulsified oily wastewater is hindered by their dynamic interfacial instability and insufficient inherent self-cleaning capacity. Herein, the polyvinyl alcohol-tannic acid (PVA-TA) hydrogel decorated polyacrylonitrile (PAN) nanofiber composite membrane with super-wetting and photothermal-catalytic self-cleaning features was constructed via hydrogen bond crosslinking and nano-reinforcement of thorn ball-like Bi 19 Br 3 S 27 -PDA-Bi 4 O 5 Br 2 core@double-shell nanohybrid (BB@PAN). The oil repellence test, density functional theory calculation, and molecular dynamics simulation verified the super-wettable and ultra-low oil adhesion behavior of BB@PAN composite membrane, resulting in highly efficient separation of oil-in-water emulsions (Flux: 1943–2626 L m −2 h −1 , oil rejection rate: 99.19–99.57 %). Owing to the nano-enhancement and multiple hydrogen bonds, the BB@PAN membrane retained its structural integrity and separation stability under extreme conditions. The broad-spectrum response and high light absorption efficiency of 3D core@double-shell structure (BOB-PDA-BBS) endowed the membrane with efficient photothermal conversion (temperature reached 62.56 °C within 24 min), enabling rapid volatilization of adhered light oils and effectively preventing a decline in permeation flux. With the support of PDA-mediated electron transfer bridge, the BB@PAN composite membrane achieved outstanding photocatalytic self-cleaning efficiency, as evidenced by its high degradation rate for various dyes. Therefore, the photothermal-catalytic double-mode self-cleaning mechanism tremendously addresses the complicated membrane fouling issues caused by oils and organic pollutants.