3D-printed super-wetting membranes with in situ grown MOF for efficient oil-water separation

Room-temperature crystallization of a cobalt-aminoterephthalate framework (CoBDC-NH₂) directly on 3D-printed polylactic acid (PLA) yields a super-wetting membrane that reconciles permeability and selectivity in oil-water separation. The ambient-pressure route dispenses with conventional hydrothermal steps and preserves the PLA architecture. Molecular dynamics (MD) combined with density-functional (DFT) calculations reveal that NaOH activation exposes carboxylate sites, while trace polyvinylpyrrolidone amplifies van der Waals forces, uniformly dispersing Co^2 + nuclei and anchoring the metal-organic framework (MOF) layer. The resulting PLA@CoBDC-NH₂ membrane delivers an oil-water mixture flux of 2.9 × 10⁵ L·m^-2·h^-1 and > 99 % rejection across six immiscible oil-water systems-values that exceed those of state-of-the-art polymeric and inorganic counterparts by up to an order of magnitude. Even after 200 gravity-driven filtration cycles, the membrane retains its initial separation efficiency. This remarkable durability originates from the synergistic interplay among the PLA scaffold, the conformal MOF coating, and an interpenetrating three-dimensional hydration-channel network, collectively circumventing the classical permeability-selectivity trade-off. Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis further elucidates the antifouling mechanism underpinning this behavior. This solvent- and energy-lean strategy offers a scalable platform for integrating MOF with biodegradable plastics, opening a path toward high-throughput, low-cost wastewater remediation.