ZIF-8 in Situ Modified Nanofiber Membranes with Photocatalytic Self-Cleaning Ability for Oil–Water Separation

Abstract

Oil–water separation is critical to ensuring the reliability of industrial oils. However, commonly used polymer separation materials can be difficult to degrade, contributing to white pollution. This study used electrospinning and seed-assisted in situ growth methods to combine the biodegradability of polylactic acid (PLA) with the high wettability and photocatalytic activity of a zeolitic imidazolate framework (ZIF-8). The resulting PLA@ZIF-8 nanofiber composites exhibited both efficient oil–water separation and self-cleaning contaminant removal abilities. The mild growth conditions of ZIF-8 and the seed-assisted method overcame the limitations regarding the in situ growth of metal–organic frameworks on PLA substrates. Experiments and COMSOL simulations revealed that the rough papillary structure of the ZIF-8 formed on the surface of the nanofiber membrane improved the oleophilicity and hydrophobicity of the PLA materials, thereby enhancing the oil–water separation performance, realizing a separation efficiency of >99.8% and maximum flux of 6280 L m–2 h–1. Under UV light irradiation, the composite membrane achieved a diesel degradation rate of 92.8%, thereby addressing the problem of reduced service life owing to fouling and pore blockage in current oil–water separation applications. The removal rate of the water-soluble pollutant methylene blue was 99.7%. Notably, the PLA@ZIF-8 membrane demonstrated excellent biodegradability and almost completely degraded after being buried in outdoor soil for 120 days, thereby avoiding white pollution. The proposed multifunctional membrane provides an efficient and environmentally friendly solution for industrial oil–water separation processes.