Preparation of ZIF-8 modified PAN/PU superhydrophobic-superoleophilic composite nanofiber membranes for oil/water separation and dye adsorption

It is still a great challenge to treat oily wastewater and organic dyes in a complex and variable water environment. In this study, polyacrylonitrile (PAN)/polyurethane (PU) was modified by the synthesis of porous nano-zeolite imidazolium skeleton (ZIF-8), and PAN/PU@ZIF-8 composite nanofiber membranes with high hydrophobicity were prepared by electrospinning technology. After the synergistic effect of ZIF-8 and PU, the prepared fibrous membranes showed excellent superhydrophobic properties with a contact angle of 150.5° to water in air. The prepared PAN/PU@ZIF-8 composite nanofiber membranes showed good separation effects on different oil/water mixtures and water-in-oil (W/O) emulsions, with oil fluxes of up to 6391.01 L·m⁻²·h⁻¹ for different oil/water mixtures and the separation efficiencies were all above 99.15 %. Meanwhile, the separation fluxes of several different W/O emulsions were up to 943.47 L·m⁻²·h⁻¹, and the separation efficiencies were all above 98.6 %. Not only that, the PAN/PU@ZIF-8 composite nanofiber membrane possessed good adsorption effect on common organic dyes such as rhodamine B (RhB) and methylene blue (MB), and the maximum adsorption amount was up to 93.80 mg/g. Meanwhile, the removal of MB and RhB by the prepared nanofiber membrane was 96.84 % and 83.66 % within 3 h, respectively. In conclusion, we prepared a ZIF-8 doped superhydrophobic PAN/PU@ZIF-8 composite nanofiber membrane by electrospinning technology, which is capable of separating W/O emulsions. It is capable of separating W/O emulsion and adsorbing organic dyes at the same time, which provides a new vision and direction for the treatment of oily wastewater and organic dyes in the complex and variable water environment.