Highly Efficient\nOil–Water Separation in Different\nScenarios through Synergistic Self-Assembly of ZIF-67@PPy Coatings\nwith Unique Wetting Properties

In recent years, oil pollution and industrial organic\npollutants\ndischarge has become a major problem affecting the ecological and\nhuman living environment, and the removal of oil in oily wastewater\nis increasingly urgent, especially for emulsion separation. Therefore,\nit is crucial to develop efficient oil–water separation membranes\nwith low cost, green sustainability, and ease of operation. Herein,\nan ingenious spraying hybrid coatings containing ZIF-67 (Zeolitic\nImidazolate Framework-67) and polypyrrole (PPy) onto stainless steel\nmesh (SSM) and polyvinylidene fluoride (PVDF) was proposed. Through\nsolidification and cooperative self-assembly to build rough structures,\noil–water separation membranes ZIF-67@PPy SSM and ZIF-67@PPy\nPVDF have been obtained, which are hydrophilic and oleophilic in air\nand superoleophobic underwater. Depending on the scenario, on-demand\nseparation of light oil/water mixtures and oil-in-water emulsions\ncan be easily realized. The resulting oil–water separation\nmembranes performed well that the separation efficiency of ZIF-67@PPy\nSSM can exceed 99.3% for all kinds of light oil/water mixtures, with\na water flux of up to 66250 L/(m<sup>2</sup>·h), and maintains\na separation efficiency of 98.5% even after 50 cycles. ZIF-67@PPy\nPVDF has a separation efficiency of more than 99.4% for various oil-in-water\nemulsions, and sustains outstanding performance despite undergoing\n10 cycles. In addition, ZIF-67@PPy SSM and ZIF-67@PPy PVDF are sustainable\nin harsh environments, with good mechanical durability and some antimicrobial\nproperties. The coatings prepared in this work that can be used for\nthe separation of light oil/water mixtures and oil-in-water emulsions,\nand the proposed combination of multiple separation strategies are\nexpected to improve the selectivity, improve efficiency, enhance contamination\nresistance, and increase accessibility of oil–water separation\ntechnologies.