A self-cleaning super-hydrophilic PAN/CS/Ti nanofibrous membrane for highly efficient oil-in-water emulsion separation under gravity

Membrane separation is an efficient purification way to treat large quantities of oily wastewater. The core challenge of membrane separation technology in practical applications is to address membrane fouling and establish sustainable separation capabilities. A super-hydrophilic and self-cleaning nanofibrous membrane is designed and prepared in a large-scale, cost-effective and environmentally friendly process for oily wastewater efficient purification. The polyacrylonitrile/chitosan (PAN/CS) matrix membrane material prepared by co-electrospinning method has excellent self-cleaning ability after amorphous titanium dioxide coating (PAN/CS/Ti). The PAN/CS/Ti membrane not only shows super hydrophilicity (WCA ∼ 0°) and underwater super oleophobicity (UWOCA ∼ 153°) but also exhibits excellent chemical stability even in harsh environments without sacrificing separation performance. Due to the uniform modified micro-nanoporous structure, PAN/CS/Ti membrane has significant gravity-driven separation flux with high efficiency and excellent reusability for surfactant-free and surfactant stabilized oil-water emulsion. In addition, PAN/CS/Ti membrane also shows outstanding separation performance with flux > 2200 L·m −2 ·h −1 for high concentration oil-water emulsions (oil content above 20 %). Overall, this study prepared the super-hydrophilic and self-cleaning PAN/CS/Ti nanofibrous membrane by a simple and scalable approach with outstanding separation performances, which can be widely used in various emulsion separation, and practically as the effective solution for oily wastewater treatment.