Multifunctional nanofiber membrane for high removal efficiency of biological/organic contaminations and oil-in-water emulsion under gravity-driven separation

Treating oily wastewater is a significant challenge, and developing cost-effective, durable, and efficient membranes is crucial for this purpose. This study introduces a novel and simple approach to transform a superhydrophobic/superoleophilic polystyrene Fe3O410%@ PS membrane, with a contact angle of 162°, into a multifunctional superhydrophilic-underwater superoleophobic (SUS) SiO2@Fe3O4@ PS membrane, with a 0°contact angle. Fabrication entails electrospinning highly porous Fe3O410%@ PS nanofibrous membranes coated with silica nanoparticles to achieve a unique surface structure with multiscale roughness and surface energy. The resulting membrane demonstrates excellent performance in gravity-driven separation, effectively removing oils, oil-in-water emulsion, dyes, and biological pollutants while maintaining high permeability (up to 1530 L.m−2.h−1). The SiO2@Fe3O4@ PS nanocomposite membrane exhibits outstanding separation efficiency for oil/water mixtures, emulsions, algae, parasites, and organic dyes like Methylene blue (MB) with a removal effectiveness of 99.9 %. Furthermore, this multifunctional membrane nanocomposite is durable and is utilized in various challenging environments, including alkaline, acidic, salty, and hot water. It can withstand at least 50 separation cycles without retraining, which is cost-effective.