Wrinkled microsphere-modified superhydrophobic PTFE fibrous substrate for high-flux oil-water emulsion separation

Abstract

Superhydrophobic membrane is promising in treatment of oil–water emulsion wastewater, but its large-scale application is often limited by the lack of facile preparation approach. Herein, we developed a simple superhydrophobic modification strategy of ultrasonic-spraying wrinkled microspheres into a commercial polytetrafluoroethylene (PTFE) fibrous substrate. Due to the atomization effect, the sprayed polydimethylsiloxane (PDMS) solution containing ZIF-8@rGO microsphere (∼ 0.4 μm) can be uniformly assembled at the surface of the PTFE fibers, which formed a superhydrophobic membrane with a contact angle of about 152°. The ZIF-8@rGO/PDMS coating decreased the boundary stresses between the oil and PTFE fiber surfaces, leading to an enhanced velocity field of the oil molecules from the fluid dynamics simulations. The resultant ZIF-8@rGO/PDMS/PTFE membrane exhibited an oil flux of 4478 L m^-2h⁻¹ together with a rejection above 99.6 % for water-in-toluene emulsions separations, which is competitive among the reported emulsion-separation membranes. This work would provide a straightforward strategy for production of superhydrophobic membrane materials.