In situ cross-linked superwetting nanofibrous membranes for ultrafast oil–water separation

Abstract

Creating a practical and energy-efficient method with high efficacy to separate oil–water mixtures, especially those stabilized by surfactants, has proven to be extremely challenging. To overcome this challenge, a novel and scalable strategy was developed for the synthesis of superhydrophilic and prewetted oleophobic nanofibrous membranes by the facile combination of in situ cross-linked polyethylene glycol diacrylate nanofibers supported on polyacrylonitrile/polyethylene glycol nanofibrous (x-PEGDA@PG NF) membranes. The as-prepared x-PEGDA@PG NF membranes have shown superhydrophilicity with ultralow time of wetting and promising oleophobicity to achieve effective separation for both immiscible oil–water mixtures and oil-in-water microemulsions solely driven by gravity. These new membranes having a good mechanical strength of 14 MPa and mean pore sizes between 1.5 and 2.6 μm have shown a very high flux rate of 10 975 L m⁻² h⁻¹ with extremely high separation efficiency (the residual oil content in filtrate is 26 ppm). More importantly, the membranes exhibit high separation capacity, which can separate 10 L of an oil–water mixture continuously without a decline in flux, and excellent antifouling properties for long term use, thus making them important candidates for treating wastewater produced in industry and daily life. Such membranes are also ideal for high viscosity oil purification such as purification of crude oil.