Robust multifunctional rGO/ZIF-8@PPS fibrous membrane for effective oil-water separation in harsh environments

Managing oily wastewater under harsh conditions poses a significant challenge in environmental protection. Conventional membranes are often ineffective in treating oily wastewater under complex environmental conditions and typically fail to achieve complete oil–water separation. This work reports the preparation of a reduced graphene oxide (rGO)/zeolitic imidazolate framework (ZIF-8) @ polyphenylene sulfide (PPS) fiber membrane by in-situ growth of ZIF-8 on the rGO-coated PPS fiber membrane. The incorporation of the rGO increases the roughness of the fibrous membrane and enhances the bond between the polymer membrane and the ZIF-8 layer, as the oxygen-containing groups of rGO can interact with the Zn 2+ of the ZIF-8 precursor, facilitating the preferential growth of ZIF-8 crystals on the rGO surface. The resulting rGO/ZIF-8@PPS membrane exhibits underwater superoleophobic and under-oil superhydrophilic properties, endowing it with switchable oil-water separation capabilities (oil-passing water-blocking or water-passing oil-blocking). During the oil (chloroform)/water separation process, it achieves high efficiency (99.96 %) and flux (27,176 L m −2 h −1 ). After 10 separation cycles using either water or oil as the permeating phase, the membrane maintains a high filtration flux (20,500 L m⁻² h⁻¹) and separation efficiency (99.97 %). Additionally, it can efficiently separate a range of oil/water mixtures under different acidic and alkaline conditions, retaining excellent separation efficiency and flux even after 10 cycles. This composite fibrous membrane provides a novel approach for treating large-scale oily wastewater in harsh environments.