Preparation of superhydrophilic polyimide fibrous membranes by electrostatic spinning fabrication for the efficient separation of oil-in-water emulsions

Membrane separation is considered an effective technology for treating oily wastewater. Hydrophilic, underwater oleophobic water removal membranes prepared by electrostatic spinning have received significant attention due to their excellent antifouling properties, small pore blockage, and high permeation flux. Herein, a simple and effective method was proposed for fabricating fabrics with superhydrophilic and submerged superoleophobic properties. First, the materials were co-blended with sodium dodecyl benzene sulfonate by electrostatic spinning, and then the porous fiber membrane was obtained by a step-up temperature for thermal imidization. The obtained membranes showed superhydrophilic and underwater oleophobic properties and could separate oil–water emulsions with or without surfactant stabilization while also exhibiting certain retention of methylene blue dye. The separation efficiency was driven by gravity alone, and the oil–water separation efficiency was always above 98.5% for 10 separation cycles, with a separation flux of up to 700 L·m−2·h−1. The modified membranes were tested and evaluated for various oil–water emulsions, and the separation efficiency was found to be consistently above 98.5%. In addition, the membranes showed satisfactory mechanical strength, high-temperature resistance, and excellent contamination resistance, suggesting that these membranes could serve as promising candidates for the treatment of industrial oil-in-water emulsions.