Multifunctional nanofibrous membrane fabrication by a sacrifice template strategy for efficient emulsion oily wastewater separation and water purification

Extensive progress has been made to construct superwetting membranes for oil/water separation. However, the membrane with hierarchical micro/nanostructure fabricated by chemical method generally involves tedious, time-consuming processes and cause secondary pollutants, which has greatly restricted their wide application. We herein report the rational design of a porous hybrid membrane (ZIF-8 @PAN) by water etching of sacrificial polyvinylpyrrolidone (PVP) of blowing-spun polyacrylonitrile (PAN)/PVP composite nanofibrous membrane during the process of in-situ growth of ZIF-8 nanoparticles onto the fiber, for effective separation of on-in-water emulsion and water purification. Specially, the porous structures increase the gaps among the fibers, thus creating new penetration paths. The formed ZIF-8 nanoparticles improved the underwater superoleophobicity and facilitated the emulsion demulsification due to the increment of the roughness of the as-fabricated mem-brane. Therefore, the ZIF-8 @PAN membrane exhibits high flux (> 4410 L m- 2 h-1) and separation efficiency (> 99.8%) for various surfactant-stabilized oil/water emulsions (SSEs). Besides, the synergistic effect of the elec-trostatic adsorption and the ZIF-8 photodegradation also render this membrane with a high organic dye removal efficiency (>90%). Meanwhile, the membrane demonstrates outstanding antibacterial activity. Hence, the syn-ergistic effect of low oil adhesion, photocatalysis, and antibacterial effect contributes to the enhancement anti-fouling ability. Further, the membrane also exhibits good chemical stability and effective separation of complex wastewater. This strategy may shed light on the design of multifunctional membranes for the treatment of complex oily wastewater.

Automated summary

A porous hybrid membrane (ZIF-8 @PAN) was designed by water etching of sacrificial polyvinylpyrrolidone (PVP) and in-situ growth of ZIF-8 nanoparticles onto the fiber, which exhibited high separation efficiency and flux for oil/water emulsion and water purification. The presence of ZIF-8 nanoparticles improved the membrane's underwater superoleophobicity and emulsion demulsification efficiency. The membrane also demonstrated antibacterial activity, chemical stability, and effective separation of complex wastewater.