Cell Membrane Mimetic Coating for Excellent Antifouling, Antibacterial Corrosion, and Self‐Cleaning Separation of Massive Oil–Water Mixtures

Abstract

is investigated as the most effective and promising oil-water separation approach owing to its simplicity, low cost, and the applicability to separate various oily waste waters. [6][7][8][9] However, the application of filtration membranes for treating huge amount high content oil-water mixture is still impeded by the following issues.The first issue is membrane fouling by contaminant adsorption and/or pore plugging by oil droplets, which causes a severe decline of the filtration flux. [10,11] Frequent water washing or chemical cleaning is required to restore the membrane flux, [11][12][13] though it reduces membrane lifespan and increases operation cost. Thus, it is very essential and urgent to develop strongly antifouling membranes, which can efficiently and rapidly separate oilwater mixtures. [14][15][16][17][18] Among various antifouling modification strategies, surface super-hydrophilization with zwitterionic polymers has been recognized as the most effective method, since zwitterionic material surfaces can form much denser ionic groups and tightly adsorbed water layer via electrostatic interactions. [18][19][20][21] The superhydrophilic membrane surfaces can strongly resist to the adsorption of proteins and other biomolecules, as well as the adhesion of bacterial cells, particulates and oil droplets from aqueous solutions. [20][21][22][23][24][25] The second issue is low filtration flux. Most of hydrophobic polymer membranes and even some modified metal mesh membranes have low filtration flux (100-2000 L m -2 h -1 ), which is unfavorable for massive oil-water separations. [12,26] Therefore, metal meshes with strong mechanical, superhydrophilic, antifouling properties, and extremely high flux (≥30 000 L m -2 h -1 ) are necessary for the filtration treatment of large amount oilwater mixture. Although zwitterionic polymers have been immobilized onto high flux stainless steel meshes (SSMs) by mussel inspired glue of polydopamine (PDA), [27,28] the hydrophilic polymer coating is easily detachable from the skeleton under harsh conditions due to the physical interaction of PDA. [29] The corrosion of the metal meshes by saline water, as well as by bacteria, is another challenging problem need to deal with. Oilfield waters and crude oil usually contain iron-oxidizing bacteria (IOB) and sulfate-reducing bacteria (SRB). [30,31] The adhesion of bacteria on metal surfaces is a crucial step in initiating microbiologically influenced corrosion. [32,33] More Massive oil-water mixtures produced from both industries and frequent oil spill incidents have threatened water ecosystems. A highly efficient separation membrane with ultrahigh filtration flux and excellent antifouling performance is created to deal with oil-water mixtures. The filtration membrane is fabricated by anchoring a phosphorylcholine copolymer (PMEN) on polydopamine (PDA)-precoated stainless steel mesh (SSM) surfaces, forming a durable cell outer membrane mimetic coating. The as-prepared SSM/PDA/PMEN membranes exhibit superhydrophilicity and high separation ...