Designing nanofibrous membrane with biomimetic caterpillar-like structured for highly-efficient and simultaneous removal of insoluble emulsified oils and soluble dyes towards sewage remediation.

Abstract Purification of insoluble emulsified oils and soluble organic pollutants from sewage has attracted tremendous attention in today's society. Herein, a stable and environmentally friendly nanofibrous membrane with hierarchical caterpillar-like structure was fabricated via in-situ hydrothermal growing the nickel-cobalt layered double hydroxides (NiCo-LDHs) on the polyacrylonitrile (PAN) electrospun nanofibers. The wrapped hydrophilic NiCo-LDHs constructed the hierarchical structure and endowed the membrane attractive superhydrophilicity (≈0°)/underwater superoleophobicity (≈161°) and enhanced oil-repellency performance. Meanwhile, the NiCo-LDH@PANI/oPAN NFMs can display the ultra-fast flux of SSEs (xylene/water emulsion, 4175 L m-2 h-1) and satisfactory separation efficiency (99.07%). Moreover, the introduction of positively charged NiCo-LDHs increased plentiful adsorption active sites for membranes, which is beneficial to demulsify ionic SSEs and adsorb organic pollutants. Finally, for simultaneous purification of complex sewage by the dead-end and cross-flow filtration experiment, the composite membrane both displayed splendid removal rate of oil (> 99.0%) and dyes (> 99.0%), robust regeneration recycle-ability and no secondary pollution. Hence, it is expected that such strategy of combining electrospun and chelating-assisted in-situ hydrothermal can provide a low energy consumption and high decontamination technology for severe environmental crisis.