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Oil‐fouling of the membranes limits further application in the separation and purification of oil‐in‐water emulsions. Here, anti‐oil fouling membranes are engineered by the method of non‐solvent induced phase separation (NIPS) which enriches the polysulfonated dopamine (PSDA) and polyethyleneimine (PEI) (PSDA‐PEI) to the top surface from mixed casting solution. The obtained membrane achieves excellent anti‐oil fouling property as high as 98.2% oil rejection, yet it still possesses good flux of 2362.5 ± 110.9 and 1252.3 ± 71.8 L m−2 h−1 for the separation of 1,2‐dichloroethane‐in‐water and toluene‐in‐water emulsions. This can be attributed to outstanding hydrophilicity and super underwater superoleophobicity for mussel‐inspired PSDA‐PEI layer. In addition, the membrane also has excellent stability in acid (pH 1, 3, and 5) or alkali (pH 10 and 12) solutions. This work provides a facile method to engineer underwater superoleophobic membranes with excellent anti‐oil fouling by mussel‐inspired chemistry for oily water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A magnetic demulsifier with beetle-like structures was successfully fabricated. • The beetle-like microstructure endowed the demulsifier with anomalous wettability. • Fe 3 O 4 grains acted as solid-phase bridges to connect C-SR particles and GO sheets. • The demulsifier showed excellent separation properties for oil-in-water emulsion. • The introduction of Fe 3 O 4 and C-SR enhanced solar-assisted recyclability of GO. Owing to its high selective adsorption and excellent cyclability, superwetting materials have attracted considerable attention in environmental governance, especially oily wastewater treatment. However, the inferior separation efficiency and high recovery energy consumption seriously limit the actual application of superwetting particles in oil–water emulsion separation. Herein, inspired reversely by the water collection and water retention of the hydrophilic/superhydrophobic structure on the Stenocara beetle's back, we fabricated magnetic graphene oxide composite with beetle-like microstructure by one-step solvothermal and environmentally friendly ball milling method. Magnetic composite with superhydrophobic/superoleophilic bumps–hydrophilic underlayer exhibits high hydrophobicity/oleophilicity in air and high oleophobicity underwater. In the process of particle assembly, the Fe 3 O 4 grains with abundant oxygen vacancies peeled off from the in-situ deposited magnetic Fe 3 O 4 microspheres play a bridging role to immobilize the superhydrophobic carbon black particles on the graphene oxide (GO) surface. On the unique surface of magnetic composite, attributed to strong π–π/n–π interface adsorption and hydrophobic interaction, the oil–water separation can be rapidly demulsified and the superoleophilic bumps (superhydrophobic carbon black nanoparticles) can capture and aggregate tiny oil droplets. The hydration layer formed in the hydrophilic region effectively prevents the captured oil droplets from spreading on the composite structure, thus enhancing the emulsion separation ability of magnetic GO. More importantly, the prepared composites exhibit efficient recycling and regeneration under solar irradiation, which is superior to the recovery efficiency of traditional GO sheets lacking high self-heating components. These inverse beetle-like magnetic GO-based particles open up a new opportunity for the design and fabrication of advanced demulsifiers in the field of oil–water emulsion separation. [ABSTRACT FROM AUTHOR]

To improve the separation efficiency and decrease fouling of the membranes used in oil-in-water emulsions separation, a superhydrophilic and underwater superoleophobic TiO 2 /Al 2 O 3 composite membrane with ultra low oil adhesion was designed. TiO 2 nanorod arrays were prepared on Al 2 O 3 porous ceramic membrane surface by simple magnetron sputtering and hydrothermal oxidation. The microstructure and surface photosensitivity of TiO 2 nanorod array-coated ceramic membrane can effectively increase the efficiency of oil-water separation and reduce the degree of surface fouling. The layer of TiO 2 nanorod arrays not only reduced the pore size of traditional ceramic membrane (enhanced sieving effect of porous structures) but also endowed its superhydrophilicity (enhanced flux) and underwater superoleophobicity (enhanced oil/water selectivity and antifouling). Based on the superhydrophilicity (water contact angle (WCA) of 0°) and underwater superoleophobicity (oil contact angle (OCA) higher than 150°) of ceramic membrane, oil droplets were blocked by the membrane (oil-water separation efficiency 99.1% under gravity) and water will pass (flux is maintained at 41.8 L/(m 2  h) under gravity). It also has excellent anti-fouling ability due to the ultra-low oil adhesion force (0.084 mN) of the TiO 2 nanorod array-coating after UV irradiation. These features, combined with energy-saving, low-cost and easy-to-scale manufacturing schemes will be of great versatility and practicality in environmental rehabilitation and wastewater purification. [ABSTRACT FROM AUTHOR]

• The PVDF/PHEMA membranes were fabricated via the VIPS process. • The surfaces of the resulting membranes are rough and porous. • After surface zwitterion, the membrane displays underwater superoleophobicity. • The membranes can efficiently separate oil-in-water emulsions in resisting fouling. Oil droplets can adsorb on the surface or enter the pore channels during membrane separation, causing a decrease in water flux and increasing the number of washing and replacements, thus increasing costs. So, membrane fouling seriously limits the use of the membrane in the purification of wastewater containing oils. Generally, the underwater superoleophobic surface provides better resistance to oils, which can be fabricated by the synergistic effects of the rough structure and hydrophilic groups are required. Here, poly(vinylidene fluoride)/poly(2-hydroxyethyl methacrylate) (PVDF/PHEMA) composite membranes with the continuous sponge-like rough structure were prepared by the vapor-induced phase separation process (VIPS), and then they were furthermore co-deposited by tannic acid (TA) and N-aminoethyl piperazine propane sulfonate (AEPPS). The zwitterionic surfaces with excellent underwater anti-oil adhesion ability can efficiently separate crude oil-in-water having the flux 1056 ± 102 L m−2 h−1 bar−1 and toluene-in-water emulsions having the flux of 1593 ± 163 L m−2 h−1 bar−1, the separation efficiency is more than 99%. Moreover, they exhibit excellent underwater anti-oil adhesion ability, excellent stability, and reversibility. Our work develops rough and porous surfaces with stable underwater superoleophobicity in an efficient way, which enables the resulting membranes to be used in the continuous purification of oily wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] Janus membrane (JM) with opposite wettability has great potential in separation of oil-in-water (O/W) and water-in-oil (W/O) emulsions. In this work, we have reported a simple, low cost nanocasting/NIPS strategy for preparation of the superhydrophobic and underwater oleophobic surface of JM for the first time. Poly (vinylidene fluoride) (PVDF) and polyethylenimine (PEI) blend membranes were fabricated on PDMS modified non-woven fabric by non-solvent induced phase separation (NIPS) process. Then the as-prepared membranes were further modified with hydrophilic nano-SiO 2 to improve the hydrophilicity of the top surface. Peel off PDMS modified non-woven fabric, parts of PDMS chains were imprinted to the membrane bottom surface with micro-nano three-dimensional microstructures, resulting in superhydrophobic property. The as-prepared JM exhibits an asymmetric wettability with the water contact angle of 35.3° and 151.8° of the opposite surfaces. By changing the orientation of the membrane, oil or water can be filtered respectively. The as-prepared JM shows excellent separation performance for both O/W emulsion and W/O emulsion, the separation efficiency reached 99.72 % and 99.68 %, respectively, as well as good long-term stability. This work is expected to yield a new way to fabricate the superhydrophobic surface of JM. [ABSTRACT FROM AUTHOR]

During the water treatment process, the common polymer membranes with high interface energy are frequently contaminated by oily water. The wettability of the separation membrane surface greatly limits the application range of the membrane. Here, a facile method is reported to fabricate a hydrophilic and underwater superoleophobic coating on hydrophobic polypropylene (PP) microfiltration membrane via co-deposition of tannic acid (TA), polyethyleneimine (PEI), and dopamine (DA). After modification, the microfiltration membrane exhibits excellent hydrophilicity, outstanding acid, alkali and organic solvent resistance. In addition, they can be applied to separate n-hexane-in-water emulsions driven by self-gravity with excellent water flux (489 ± 24 Lm−2 h−1) and high separation efficiency (99.8%). The fabricated TA/DA/PEI coating with outstanding performances has great potential application in the field of oily water treatment. • A facile one-step co-deposition of TA/DA/PEI hydrophilic coating was developed to modify hydrophobic PP membranes. • These membranes can separate various oil-in-water emulsions driven by gravity with excellent water flux and separation efficiency. • The modified coating possesses excellent acid, alkali and organic solvent resistance. [ABSTRACT FROM AUTHOR]