Coating polyurethane sponge with Dy-MOF for efficient oil–water separation in complex environments.

The Dy-MOF@PU sponge can successfully carry out oil–water separation and W/O emulsion separation. To intuitively reveal the separation mechanism of the Dy-MOF@PU sponge for the emulsion, a hypothetical separation process was made. [Display omitted] • Lanthanum-based Dy-MOF was used to decorate 3D PU sponge. • Dy-MOF-F@PU sponge was successfully synthesized by a simple sedimentation method. • Explore the effect of method synthesis on the morphology and hydrophobicity. • Modified sponge with excellent mechanical flexibility, durability and repeatability. Leakage of industrial oil and organic solvents seriously harms environment and ecology yet demanding highly efficient and durable materials for oil–water separations. In this work, ultra-light and highly flexible polyurethane (PU) sponges were engineered to 3D oil–water separators by coating the dysprosium metal organic framework (Dy-MOF) onto the surfaces of the PU frames. Through a facile impregnation, the Dy-MOF was attached to the full frames of the sponges. Consequently, liquid contact surfaces were extended from these on top layers to the whole rack. Superhydrophobicity with water contact angles up to 152.08° and lipophilicity enable continuous separations of dichloromethane from water through the resulted Dy-MOF@PU sponges in a continuous mode. The modified sponges own high gravimetric absorption capacities for oil and organic solvents, and high resistances to temperature variations, corrosive solutions, and mechanical abrasions, thanks to the well-connected and stable superhydrophobic/supportive interfaces. An efficient separation was successfully piloted for oily wastewater consisting of water-in-oil emulsions stabilized by surfactants, demonstrating the potential of practical water treatment of Dy-MOF@PU in complex environments. Mechanism leading to superior oil–water separation capability was studied and inferred as the combined effects of the physical and chemical properties arisen from the stable Dy-MOF and flexible but porous matrix. [ABSTRACT FROM AUTHOR]