Oily dyeing wastewater separate by PAN-EC-SiO2 EFM dual function in a single membrane separation process

Oily dyeing wastewater poses significant environmental hazards and therefore requires effective treatment. Although electrospun fiber membranes (EFMs) have been employed for oily dyeing wastewater treatment, conventional approaches typically involve a two-step process. This study presents a novel single-step modification method for EFMs, enabling efficient treatment of oily dyeing wastewater through a simplified single-membrane separation process. Experimental results demonstrated that spontaneous self-assembly occurs between ethyl cellulose (EC) colloids and hydrophilic SiO₂ nanoparticles in mixed solutions. Furthermore, these self-assembled colloids can undergo liquid-phase-induced self-organization on polyacrylonitrile (PAN) electrospun fiber membranes (EFMs), leading to a "welding" effect that firmly immobilizes both EC and hydrophilic SiO₂ nanoparticles onto the PAN fibers.The self-assembly process effectively prevented the agglomeration of SiO₂ nanoparticles, resulting in their uniform and stable fixation on the PAN fibers. Compared to the pristine PAN EFM, the PAN-EC-SiO₂ EFM exhibited significantly enhanced tensile strength, pH tolerance, surface roughness, hydrophilicity, hydration capacity, and methylene blue adsorption performance. Consequently, this modified membrane demonstrated dual functionality, effectively separating both oil-water emulsions and oily dyeing wastewater. During oily dyeing wastewater treatment, the PAN-EC-SiO₂ EFM achieved a methylene blue rejection rate of 92 %, an oil separation efficiency of 97.2 %, and a high flux of 153 L/m²·h.