High permeability PEG/MXene@MOF membrane with stable interlayer spacing and efficient fouling resistance for continuous oily wastewater purification

Unstable interlayer spacing of lamellar membranes would be rapidly compressed and narrowed under normal high flowrates and concentration polarization effect contributes to reduced permeation and fouling resistance. Herein, a large permeability PEG/MXene@MOF membrane with stable interlayer spacing and superior antifouling property was created via facile interface self-assembly strategy. Metal-organic framework (MOF, UiO-66-NH2) nanoparticles as supports constructed an intercalation-induced structure with hierarchical Ti3C2Tx (MXene) nanosheets, which effectively regulated the interlayer spacing and improved permeability. Hydrophilic polyethylene glycol (PEG) further enhanced the stability of intercalation structure via hydrogen bonding, so that the PEG/MXene@MOF membrane demonstrated excellent swelling resistance with an average layer spacing expansion of only 0.05 nm even after immersion in water for 8 days. Moreover, MOF particles increased the lamellar roughness and interlayer water retention capacity, resulting in the PEG/MXene@MOF membrane with remarkable separation selectivity and powerful fouling resistance (UWOCA >156°, UWOSA <5.5°). Regarding the purification of oil-in-water emulsions stabilized by surfactants, the PEG/MXene@MOF membrane exhibited extremely stable high permeability (1246 ± 12 L m−2 h−1 bar−1) and excellent efficiency (>99.7 %), even during continuous separation of high-viscosity crude oil emulsions for 60 min. In addition, the PEG/MXene@MOF membrane also exhibited superior chemical durability and mechanical robustness in strong-corrosiveness and high-salty environments (72 h), ultrasonic treatments (120 min), bending experiments (100 times) and abrasion tests (20 times). Therefore, this work provided a promising strategy to construct highly permeable membrane with stable interlayer spacing and efficient fouling resistance for practical oily wastewater purification.