Eco-friendly fabrication of hierarchical superhydrophobic nonwoven polyester membranes via sol-gel/phase inversion for ultra-high flux oil-water separation

The increasing environmental concerns arising from industrial oily wastewater and offshore oil spills necessitate the development of efficient, durable, and cost-effective oil-water separation technologies. This study fabricated a novel superhydrophobic nonwoven polyester (NWP) membrane using eco-friendly sol-gel and phase inversion methods. The membrane was engineered by integrating polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) with hydrolyzed tetraethyl orthosilicate (TEOS) and vinyltris(2-methoxyethoxy)silane (VTMEOS), forming a robust and highly porous composite material. The unique hierarchical structure exhibited exceptional hydrophobicity, with a water contact angle exceeding 150°, and demonstrated remarkable mechanical and chemical stability across a pH range of 1–13. When tested in a custom-built low-pressure (0.02 MPa) filtration device, the hydrophobic membrane achieved an ultra-high flux rate of 19,400 Lm −2 h −1 and a separation efficiency of 99.9 % over 70 cycles. The membrane's porosity (87.17 %) and finely controlled pore size distribution (0.4–1.8 μm) significantly contributed to its enhanced separation performance. Density Functional Theory (DFT) calculations further validated the chemical interactions underlying the surface modification and hydrophobic behavior. This study presents a scalable and energy-efficient membrane system, which offers a promising platform for next-generation oil-water separation in environmental remediation.