Fabrication of highly durable and robust superhydrophobic-superoleophilic nanofibrous membranes based on a fluorine-free system for efficient oil/water separation

Developing an effective and energy-efficient oil-water separation technologies for cleaning up or removing of oil contaminants from oily water is highly desired, owing to the frequent occurrence of oil spill accidents and large amounts of oil-containing industrial wastewater emissions. Here, a facile method to fabricate superhydrophobic/superoleophilic membranes based on a fluorine-free system by the combination of electrospun polyimide (PI) nanofibers and a novel in-situ polymerized polybenzoxazine (PBZ) functional containing silica nanoparticles (SNP) is proposed. The resultant PI-based membrane has outstanding superhydrophobicity and superoleophilicity with water and oil contact angles above 154 degrees and approaches 0 degrees, respectively. Simultaneously, the membrane possesses extraordinary chemical and thermal stability and high salt tolerance. Furthermore, the membrane presents high separation efficiency (above 99%) and high-flux (4798 L m(-2) h(-1)) as well as good reusability and oil content in the filtrate below 5 ppm for separation of various oil/water mixture. Significantly, these studies offer a simple yet cog-effective technique to fabricate superhydrophobic/superoleophilic membranes and have potential use for oily wastewater treatment and oil spill clean-up.