Cubic MOF coated stainless steel mesh with underwater superoleophobicity for highly efficient oil/water separation

A novel superhydrophilic and underwater superoleophobic material (MOF-5/PDA/SSM) with high flux, outstanding oil/water separation performance and durability was prepared. The stainless steel mesh (SSM) was modified by MOF-5 crystals and PDA. The introduction of MOF-5 can improve the hydrophilicity of SSM and achieve high water flux at the same time. PDA is a substance with strong adhesion which can be used as an effective bonding intermediate. The preparation strategy includes the self-polymerization of dopamine and the deposition of cubic clusters on SSM via hydrothermal reaction. The MOF-5 particles on the mesh are cubic hexahedral crystal with a uniform size diameter, which can trap water in the rough microstructure, forming a strong hydration barrier layer or composite water-solid interface on its surface, hindering the penetration of oil. The super-hydrophilicity and underwater superoleophobicity of the modified meshes were introduced by pre-wetting surface. The FTIR, XRD, XPS and SEM characterizations demonstrated that the successfully growth of MOF-5 and a rough structure was obtained on the mesh. The special wetting and the robustness of the fabricated mesh led to the outstanding separation efficiency (up to 99.5%), excellent recyclability (about 20 cycles) and high water flux (53.9 k L m−2 h−1). The mesh also showed remarked water flux and various oil/water mixtures separation performance. Particularly, the successfully prepared materials were found to be significant stable under various physical and chemical extremes environments, including maintain UWOCA>150 under acid/alkali media, marvelous performance after 120 min of continuous separation and high anti-oil intrusion pressure. The combination of metal organic framework and stainless steel mesh may provide a candidate application to effective oil-water separation.