Superhydrophobic Nanocomposite Polysulfone Fibrous Membranes Incorporated with Phenyltriethoxysilane-Modified Silica...

Oily wastewater originating from industrial activities and domestic effluents has been one of the major sources of pollution, leading to contamination of clean water supplies and jeopardizing aquatic ecosystems. Water pollution accompanied by water scarcity manifests the compelling need for advanced next-generation membrane-based treatment strategies. In this study, high flux, robust, durable, and superhydrophobic nanocomposite fibrous membranes including silica nanoparticles were produced via electro-blow spinning (EBS) of polysulfone (PSU). To enhance water repellency, the surface of nanoparticles was functionalized with phenyltriethoxysilane (PTES). The amount of disperse phase was optimized by the addition of PTES-modified silica (SPTES) nanoparticles into the polymer spinning solution at changing ratios between 1 and 10 wt %. The best membrane performance was obtained with the membrane specimen including 5 wt % SPTES (PSU@SPTES-5). This SPTES ratio stimulated the dense distribution of silica nanoparticles, resulting in distinct surface roughness. Due to the incorporation of SPTES, the water contact angle (WCA) of pristine PSU membrane was enhanced from hydrophobic (129.9°) range to superhydrophobic (154.3°) range. The PSU@SPTES-5 membrane sample exhibited excellent performance in both strength and elongation, maintaining durability while preserving flexibility. Furthermore, its initial decomposition temperature increased from 437 to 461 °C, while char yield shifted from 12.2 to 30.9% relative to PSU. The separation efficiencies of PSU@SPTES-5 were measured as 99.4%, 96.6%, 99.9%, and 86.5% for diesel, CCl₄, petroleum spirit, and sunflower oil (SFO), respectively. After 20 consecutive separation cycles, PSU@SPTES-5 retained a separation efficiency above 97.2%. The efficiency of 86.5% at gravity-driven separation increased to 98.6% when the pressure-driven system was employed for SFO. Upon testing against diesel- and SFO-in-water emulsions (99:1 = O/W (w/w)), PSU@SPTES-5 sample showed fluxes of 1203 L/m² h and 63L/m² h, with corresponding separation efficiencies of 99.3% and 97.2%, respectively. When evaluated under harsh conditions, even after 24 h exposure to 2 M HCl, 2 M NaOH, and UV irradiation, the membrane retained its separation efficiency above 97% in all cases after 20 cycles.