Flexible Hierarchical-Porous TiO2/ZnO@Carbon Nanofiber Membranes with Synergistic Oil–Water Separation and Visible-Light-Driven Self-Cleaning for Sustainable Wastewater Remediation

Oily wastewater and antibiotic residues (e.g., tetracycline hydrochloride, TCH) pose significant threats to aquatic ecosystems and human health. Conventional remediation technologies frequently suffer from low efficiency, secondary pollution, or high energy consumption. Rigid ceramic membranes, once deemed the “gold standard” in separation fields, exhibit inherent drawbacks, including brittleness, low porosity, and severe fouling propensity. To address these challenges, flexible hierarchical-porous carbon nanofiber membranes codoped with TiO2/ZnO heterojunctions (TZCNFMs) were successfully fabricated via electrospinning, preoxidation, and carbonization processes. Research findings demonstrated that the optimized TZCNFM (with a specific TTIP/Zn(OAc)2 mass ratio) exhibited superior comprehensive performance, characterized by a rough surface with nanoprotrusions, a large specific surface area, and favorable tensile strength. This optimized membrane showed strong hydrophobicity and superoleophilicity, enabling high separation efficiency for water-in-oil emulsions. Under visible light irradiation, the constructed TiO2/ZnO heterojunctions in TZCNFM2 formed a staggered band structure, which not only effectively suppressed the recombination of photogenerated electron–hole pairs but also narrowed the overall band gap of the composite system to extend the light response range to the visible region, realizing efficient degradation of antibiotic residues. Furthermore, the membrane maintained negligible flux decline after multiple cyclic uses, confirming its excellent reusability. This work highlights the synergistic regulation of TiO2/ZnO on the structure, wettability, and mechanical stability of carbon nanofiber membranes, providing a scalable strategy for fabricating high-performance self-cleaning membranes in aquatic pollution remediation.