One-step fabrication of robust Stenocara beetle-inspired membrane deriving from polyethylene terephthalate (PET) waste for enhancing emulsion separation

The purification of emulsified water from waste oil has become a major research topic. Stenocara beetle-inspired wettable membranes have emerged as separating-efficient designs for purification of oil due to surface energy difference and surface roughness driven demulsification, but they are still suffering from tedious preparation and low robustness. Herein, a one-step electrospinning/electrospraying process was employed to construct Stenocara beetle-like membrane using waste PET and tetrabutyl titanate (TBT) as raw materials for water-in-oil emulsion separation. Specifically, the synchronized deposition process combines electrospinning high-hydrophobic PET fiber membrane and electrospraying superhydrophilic TiO2 particles (superhydrophilic bumps) generated from hydrolysis of TBT on the PET membrane surface, leading to a similar structure to Stenocara beetle. During the separation process, the bumpy superhydrophilic TiO2 particles can capture and aggregate tiny water droplets even though the droplet size is smaller than the membrane pore size. Moreover, this Stenocara beetle-like structure exists both on the surface and interior of the samples, resulting in the boosted demulsification ability and excellent separation efficiency up to 99.8 % and flux as high as 6392 L m-2h 1. Stenocara beetle-like membrane also exhibits strong mechanical properties and strain of the membrane is up to 128.8 %. Even after the friction test, the membrane maintained cycling stability and abrasion resistance with separation flux higher than 3500 L m-2h 1. Overall, this efficient one-step strategy can open up new avenues to fabricate advanced superwetting membranes in the field of emulsion separation.