Flexible MOF nanosheet based membranes for high-flux antifouling oil/water separation and reverse cross-flow cleaning

Oil droplet deposition on membrane surfaces and within pores remains a fundamental cause of severe flux decline in oil/water separation processes. Inspired by recent advances in flexible nanostructures, we present vertically aligned and flexible ZIF-8 nanosheets based oil/water separation membranes. The membranes exhibit exceptional separation performance with a water flux of 3575 L·m⁻²·h⁻¹·bar⁻¹ and oil rejection exceeding 98%. Molecular dynamics (MD) and density functional theory (DFT) simulations reveal that the hydrophilic-modified nanosheets exhibit strong binding to water molecules (-648.5 kcal/mol) while showing negligible affinity for n-hexane (close to 0 kcal/mol), elucidating the molecular basis for hydration layer formation during oil/water separation. The membranes demonstrated exceptional anti-fouling properties through a novel hydraulic-responsive self-cleaning mechanism that eliminated the need for chemical cleaning agents. This dynamic cleaning mechanism enables a high flux recovery ratio (>85%) and low irreversible fouling. Even after 10 cycles with surfactant-stabilized emulsions, separation efficiency remains uncompromised. This work offers a robust and sustainable strategy for high-performance oily wastewater treatment.