Antifouling hydrolyzed polyacrylonitrile/graphene oxide membrane with spindle-knotted structure for highly effective separation of oil-water emulsion

Polyacrylonitrile/graphene oxide (PAN/GO) composite fibers with spindle-knot structure have been fabricated by facile electrospinning and then hydrolyzed (H-PAN/GO) for tailoring their chemical features, and their separation performance for oil-water is evaluated. Herein, bio-inspired spindle-knot structures are induced by the GO sheets, which may be attributed to the mismatch between GO size and fiber diameter and the strong interaction between PAN and GO. It is found that H-PAN/GO membrane with GO concentration at 7% (H-PAN/GO7%) is superhydrophilic in air and ultralow-oil-adhesion under water. As a result, the H-PAN/GO7% membrane exhibits ultra-high flux (~3500 LMH), satisfied rejection ration (~99%) and outstanding flux recovery ratio (~99%) for separating oil-water emulsion. These outstanding separation performances mainly are attributed to the combination of chemical features of hydrolyzed PAN and spindle-knotted structure induced by GO. Moreover, self-transport of oil along spindle-knotted fiber under water is demonstrated by Lattice Boltzmann method (LBM) and the anti-fouling mechanism of this structure was also explained in this paper. The H-PAN/GO fibrous membrane offers a novel insight into fabricating next generation membrane to separate oil-water emulsion.