Microbubble-assisted double-defense design of anti-fouling superhydrophilic membrane for sustainable emulsion separation and synergistic pollutant degradation

Conventional superwettable membranes employed for oil/water emulsion separation often exhibit limited operational longevity due to insufficient demulsification efficiency and susceptibility to surface fouling in practical scenarios. Herein, a superhydrophilic PVA/ZnIn 2 S 4 nanofibrous membrane (PZM) with exceptional wettability, visible-light-driven photocatalytic overall water splitting activity, and self-cleaning functionality is developed via a simple one-step electrospinning method. Microbubbles are generated and released in situ from the membrane surface under visible light irradiation spontaneously without adding harmful initiators, which may penetrate adhered oil contaminants from the surface and remove them through enhanced buoyancy. This dynamic microbubble layer integrated with the static superhydrophilic hydration layer creates a dual physical barrier, thus effectively inhibiting oil adhesion and actively protecting the surface from oil fouling. Additionally, the as-produced microbubbles can attract and float oil droplets, thereby facilitating demulsification. Consequently, this microbubble-assisted strategy can effectively mitigate permeability reduction caused by membrane fouling, enhancing both permeability and separation efficiency to achieve sustainable self-cleaning performance in oil-in-water emulsion separation. Over 180 min of continuous operational testing, the PZM not only achieves full permeability recovery, but also progressively increases the separation efficiency to 99.7 %. Furthermore, the incorporation of ZnIn 2 S 4 nanoflowers endows the membrane with simultaneous photocatalytic dye degradation capability, enabling synchronous treatment of complex wastewater containing both emulsified oils and organic pollutants. This work provides a novel strategy for developing multifunctional separation membranes capable of highly efficient emulsion separation and simultaneous pollutant degradation, demonstrating broad application prospects in oily wastewater treatment and environmental remediation.