Excellent Underwater Superoleophobicity Research Articles

All cellulose-based superwetting aerogel/wood composite with disordered/ordered pores structure for rapid emulsion separation

Rapid and efficient separation of oil from emulsions is critically required prior to addressing the global challenge of oily sewage, but most separation membranes encounter intractable challenges in terms of the trade-off effect between separation efficiency and flux, as well as the use of petrochemical feedstocks. Herein, an all-biomass wood/aerogel composite with a disordered/ordered structure was constructed by filling cellulose nanofibers aerogel into the intertubular cavities of delignified wood using cotton and wood as building blocks through a series of processes, including casting, regeneration, and freeze-drying. The parallel channels of wood and the porous structure of aerogel constitute the special disordered/ordered pores structure, which accelerates vertically oriented permeation and enhances emulsified droplets coalescence for demulsification. In addition, the aerogel/wood composite retains the inherent hydrophilicity of cellulose and exhibites excellent underwater superoleophobicity with an underwater oil contact angle of 159.6°, which is chemically stable and salt resistant. The unique disordered/ordered structure and superwettability of the aerogel/wood composite contribute to its exceptional separation efficiency (99.25 %) and high flux (2580 L·m−2·h−1) for the separation of oil-in-water emulsions when driven only by gravity. Additionally, the composite shows good utility and ease of cycling. These outstanding properties highlight its promising practical application in the oil-related industry.

Poly(vinylidene fluoride) membrane design for efficient oil-in-water emulsion separation: Integrating superhydrophilicity, photocatalysis and self-cleaning

To solve the increasingly serious wastewater problems, developing membranes with excellent filtration performance and anti-fouling property has been a research focus. Herein, hydrophilic tannic acid/cysteine/tyrosine@titanium (TA/Cys/Tyr@Ti) double crosslinked coating was constructed on the poly (vinylidene fluoride) (PVDF) microfiltration membranes by two-step coating method, while the mineralized titanium dioxide (TiO2) nanoparticles were utilized to produce superhydrophilic membranes. The synergistic effect of the multilayered nanostructure and hydrophilic groups enables excellent underwater superoleophobicity and anti-fouling property of modified membranes. The addition of TiO2 provides photocatalytic degradation and self-cleaning properties. The optimized modified membrane (MF-4) showed outstanding oil–water separation potential (emulsion flux of 2760 ± 30 L·m−2·h−1, oil rejection rate of 99.5 ± 0.3 %) and stable recycling filter capacity. Moreover, MF-4 was able to efficiently degrade methylene blue under UV light, which was 99.1 % at 90 min. The flux recovery rate (FRR) was 97.4 % following simulated contamination and regeneration with bovine serum albumin. After UV irradiation, the FRR appeared to be significantly enhanced, proving its great anti-fouling and self-cleaning properties. This modified membranes with superhydrophilic and self-cleaning properties have great application potential in oily wastewater and achieving automatic operation of wastewater treatment.

Double-drying 3D lamellar-structured aerogel membrane for efficient oil-water separation and long-lasting antibacterial activity

Conventional oil-water separation membranes are difficult to establish a trade-off between membrane flux and separation efficiency, and often result in serious secondary contamination due to their fouling issue and non-degradability. Herein, a double drying strategy was introduced through a combination of oven-drying and freeze-drying to create a super-wettable and eco-friendly oil-water separating aerogel membrane (TMAdf). Due to the regular nacre-like structures developed in the drying process and the pores formed by freeze-drying, TMAdf aerogel membrane finally develops regularly arranged porous structures. In addition, the aerogel membrane possesses excellent underwater superoleophobicity with a contact angle above 168° and antifouling properties. TMAdf aerogel membrane can effectively separate different kinds of oil-water mixtures and highly emulsified oil-water dispersions under gravity alone, achieving exceptionally high flux (3693 L·m−2·h−1) and efficiency (99 %), while being recyclable. The aerogel membrane also displays stability and universality, making it effective in removing oil droplets from water in corrosive environments such as acids, salts and alkalis. Furthermore, TMAdf aerogel membrane shows long-lasting antibacterial properties (photothermal sterilization up to 6 times) and biodegradability (completely degraded after 50 days in soil). This study presents new ideas and insights for the fabrication of multifunctional membranes for oil-water separation.

Solvent-tolerant lignosulfonate-attapulgite/calcium carbonate coating on nylon filter mesh for oily water treatment

Due to the rapid increasing drainage of oily wastewater, robust and durable filtration materials with underwater superoleophobic coatings are highly desired. The existing underwater superoleophobic filter materials for oil/water separation are always subject to mechanical and chemical damages, causing the significant loss of superoleophobicity. Herein, a robust and tolerant nylon filter mesh (NFM) with underwater superoleophobicity was fabricated through simple layer-by-layer (LBL) assembly of lignosulfonate (LS), attapulgite (APT) nanorods, calcium ion, and carbonate on NFM. Compared with LS@CaCO3 assembly, the obtained LS-APT@CaCO3 assembly on NFM exhibits good micro/nano-structure, uniform distribution, and excellent underwater superoleophobicity (oil contact angle: > 156°). Moreover, after the fabricated mesh is subjected to the immersion in corrosive environments (acid, base, and salt aqueous solutions) and hot water as well as severe mechanical scratch, the oil contact angle are still higher than 147.5°, implying superb durability. More importantly, the as-obtained NFM is able to treat a variety of oil/pure water and oil/corrosive solution mixtures with separation efficiencies of over 98.2 %. Therefore, the as-prepared mesh has a huge application potential in oil-polluted water remediation due to the simple, facile, and eco-friendly preparation process.

A colorimetric and fluorescent probe of lignocellulose nanofiber composite modified with Rhodamine 6G derivative for reversible, selective and sensitive detection of metal ions in wastewater

Heavy metal ions have extremely high toxicity. As the top of food chain, human beings certainly will accumulate them by ingesting food and participating other activities, which eventually result in the damage to our health. Therefore, it is very meaningful and necessary to design a simple, portable, stable and efficient material for heavy metal ions detection. Based on the spirolactam Rhodamine 6G (SRh6G) fluorescent probe, we prepared two types of nanocomposite materials (membrane and aerogel) by vacuum filtration and freeze-drying methods with lignocellulose nanofiber (CNF) as a carrier, polyvinyl alcohol (PVA) and glutaraldehyde (GA) as the cross-linkers. Then the microstructure, chemical composition, wetting property, fluorescence intensity and selectivity of as-prepared SRh6G/PVA/CNF would be characterized and analyzed. Results showed that SRh6G/PVA/CNF nanocomposites would turn red in color under strong acidic environment and produced orange fluorescence under ultraviolet light. Besides, they were also to detect Al3+, Cu2+, Hg2+, Fe3+ and Ag+ through color and fluorescence variations. We had further tested its sensitivity, selectivity, adsorption, fluorescence limits of detection (LOD) to Fe3+ and Cu2+. The test towards real water samples (hospital wastewater, Songhua River and tap water) proved that SRh6G/PVA/CNF nanocomposites could detect the polluted water with low concentrations of Fe3+ and Cu2+. In addition, SRh6G/PVA/CNF nanocomposites have excellent mechanical property, repeatability, superhydrophilicity and underwater superoleophobicity, which may offer a theoretical reference for the assembly strategy and detection application of cellulose-based fluorescent probe.

PVDF-based nanofiber membrane decorated with Z-scheme TiO2/MIL-100(Fe) heterojunction for efficient oil/water emulsion separation and dye photocatalytic degradation

Membrane separation is one of the most widely used methods for water purification, but membrane fouling is a stumbling block that must be overcome for its further promotion and application. In this work, a self-cleaning PVDF-based hybrid nanofiber membrane with core-sheath structure were constructed via electrospinning and in-situ synthesis, using polyvinylidene fluoride/polyvinyl pyrrolidone (PVDF-PVP) electrospun nanofibers as skeleton cores and in-situ synthesis of Z-scheme TiO2/MIL-100(Fe) heterojunctions as photocatalytic sheaths. The hybrid membrane exhibited excellent superhydrophilicity (water contact angle of 0°) and underwater superoleophobicity (underwater oil contact angle of 161.4°) with high permeate fluxes and superior separation efficiencies (more than 99.5%) for various oil/water emulsions. Furthermore, the Z-scheme TiO2/MIL-100(Fe) heterojunctions anchored on the nanofibers possessed robust photocatalytic activity with the removal efficiency of dyes up to 99.9% under simulated sunlight. More importantly, the membrane has excellent recyclability due to its outstanding anti-fouling and self-cleaning properties. Therefore, the hybrid membrane has attractive potential application in wastewater purification.

Superhydrophilic and Underwater Superoleophobic Copper Mesh Coated with Bamboo Cellulose Hydrogel for Efficient Oil/Water Separation.

Super-wetting interface materials have shown great potential for applications in oil-water separation. Hydrogel-based materials, in particular, have been extensively studied for separating water from oily wastewater due to their unique hydrophilicity and excellent anti-oil effect. In this study, a superhydrophilic and underwater superoleophobic bamboo cellulose hydrogel-coated mesh was fabricated using a feasible and eco-friendly dip-coating method. The process involved dissolving bamboo cellulose in a green alkaline/urea aqueous solvent system, followed by regeneration in ethanol solvent, without the addition of surface modifiers. The resulting membrane exhibited excellent special wettability, with superhydrophilicity and underwater superoleophobicity, enabling oil-water separation through a gravity-driven "water-removing" mode. The super-wetting composite membrane demonstrated a high separation efficiency of higher than 98% and a permeate flux of up to 9168 L·m-2·h-1 for numerous oil/water mixtures. It also maintained a separation efficiency of >95% even after 10 cycles of separation, indicating its long-term stability. This study presents a green, simple, cost-effective, and environmentally friendly approach for fabricating superhydrophilic surfaces to achieve oil-water separation. It also highlights the potential of bamboo-based materials in the field of oil-water separation.

Dual role of silk fabric functionalized with polymer/GO-tungsten oxide nanocomposites as superwettable membranes and photocatalysts for removing dye contaminants and emulsion separation

BackgroundWastewater containing hazardous dye contaminants has aroused significant concern and poses a great challenge to membrane technology. Herein, a novel bio-inspired silk fabric membrane modified with L-histidine functionalized polyglycidyl methacrylate composited with graphene oxide and tungsten oxide (amino-PGMA/GO-WO2.72) was successfully produced to treat wastewater contaminants. MethodsAn urchin-like WO2.72 nanoparticle is synthesized using the hydrothermal method. The synthesized WO2.72 nanoparticles are composited with an amino-functionalized PGMA/GO via dispersion polymerization techniques. Finally, a flexible membrane is created by dip-coating silk fabric in the amino-PGMA/GO-WO2.72 nanocomposite solution. Significant findingsThe fabricated membrane showed excellent superhydrophilicity, underwater superoleophobicity, and outstanding performance in separating methylene blue (MB) dye-mixed emulsions under gravity with a high permeation flux of about 1690 ± 40 L m−2 h−1. The amino-PGMA/GO-WO2.72 modified silk fabric membrane showed remarkable stability, allowing the membrane to withstand a high separation efficiency of 99 %. Furthermore, the photo-responsive ability of the heterojunction GO-WO2.72 catalyst materials present in the modified membrane can lead to the reduction of toxic nitro phenols, degradation of various dyes and textile effluents wastewater with high photodegradation efficiency under UV–-visible and solar light irradiation.

Direct-coating of cellulose hydrogel on PVDF membranes with superhydrophilic and antifouling properties for high-efficiency oil/water emulsion separation

As a well-known natural and innocuous plant constituent, cellulose consists of abundant hydroxyl groups and can tightly adsorb onto material surfaces hydrogen bonding, resulting in a superhydrophilic surface. In this work, the hydrophobic polyvinylidene fluoride (PVDF) membranes were modified by immersing them in cellulose hydrogel using a simple one-step process. The modified PVDF membrane exhibited excellent resistance to fouling and oil adhesion, making it highly effective in separating various oil-in-water emulsions. The cellulose-modified PVDF membranes achieved a high oil rejection rate (>99 %) and a maximum separation flux of 2675.2 L·m−2·h−1. Furthermore, even an oil-in-water emulsion containing bovine serum albumin maintained a steady permeation flux after four filtration cycles. Additionally, these cellulose-modified PVDF membranes demonstrated excellent underwater superoleophobicity across a wide range of pH levels and high saline conditions. Overall, these cellulose-modified superhydrophilic PVDF membranes are sustainable, environmentally friendly, easily scalable, and hold great promise for practical applications in oily wastewater treatment.

Advanced super-wetting biaxial polypropylene membrane with hierarchical rough surface for multipollutant removal from oily wastewater

The hazardous toxicity of oily wastewater creates a negative impact on the environment and ecosystem that has made water separation an open challenge on a global scale. A promising and workable tactic to prevent contaminations and effective water separation from oily wastewater has been proved using cutting-edge advanced polymeric membrane-based separation technology. Excessive hydrophobicity, contamination vulnerability, and membrane fouling are recurring and crippling problems for the treatment of oily wastewater. To overcome these difficulties, we design a facile, scalable, and highly efficient layer-by-layer modification technique using polyethylene imine and levo-3,4 dihydroxyphenylalanine cross-linked multi-layer assembled rough biaxial polypropylene membrane surface. The synergistic development of the rough surfaces causes the embeddedness of wetting properties of the modified membrane with excellent superhydrophilicity (0º) and underwater superoleophobicity (∼164.3º). Such great underwater superoleophobicity shows a superior oil-repulsive property that helps to achieve high separation efficiency (99.9 %) and permeate flux (2325.3 L m−2 h−1). Additionally, our modified membrane holds excellent anti-bacterial properties against S. aureus and E. coli bacteria with 92.8 % and 88.6 % viability, respectively. Notably, this highly efficient modified membrane is capable of removing multi pollutants (oil particles and bacteria) from oily wastewater in a more energy-efficient way.

Anti-oil fouling poly(vinylidene fluoride) membrane with excellent underwater superoleophobicity and high-efficient photo-Fenton oxidation for oily water purification

Oil fouling makes serious trouble to the membranes for oil-in-water emulsion separation and purification. Here, an anti-oil fouling membrane was designed and constructed by loading β-FeOOH nanorods and carbon quantum dots (CQDs) on the poly(vinylidene fluoride)/poly(2-hydroxyethyl methacrylate) blend membrane. The fabricated BM@(β-FeOOH/CQDs) membrane can efficiently separate various oil-in-water emulsions. Furthermore, BM@(β-FeOOH/CQDs) exhibits stable underwater superoleophobicity with an underwater oil contact angle (UWOCA) of 152.5 ± 1.1° and a sliding angle (SA) of 2.2 ± 0.2°, which is beneficial to prevent oil droplets from contacting and adhering to the separation porous surface. Moreover, BM@(β-FeOOH/CQDs) has excellent photo-Fenton oxidation efficiency, which can photo-activate H2O2 to degrade oil droplets on the separation membrane. The flux recovery ratio of the membrane increases by 1.8 times when the photo-Fenton reaction was activated. This work provides an effective strategy for the engineering of anti-oil fouling membranes to purify oily wastewater.

Superwetting membrane by co-deposition technique using a novel N‑oxide zwitterionic polymer assisted by bioinspired dopamine for efficient oil–water separation

Superwetting membranes have good prospective for treatment of oil-containing wastewaters. However, development of simple and environment-friendly membranes with efficient oil–water separation performance remains a great challenge that needs to be addressed urgently. In this study, inspired by the secretion of trimethylamine-N-oxide (TMAO) by saltwater fish, we report a novel N‑oxide zwitterionic polymer (PTMAO) with ultralow fouling property possessing directly linked opposite charges in their molecules and superior hydrophilicity, as compared to conventional zwitterionic ones. Using biomimetic co-deposition technique of dopamine (DA) and PTMAO, a zwitterionic polymer network was formed via self-polymerization of DA and followed by hydrogen bonding and cation-π effects between the oxidatively generated polydopamine (PD) and PTMAO. As expected, the fabricated membrane exhibited excellent superhydrophilicity and underwater superoleophobicity. The M–PD/PT/2:2 membrane achieved high efficiency of oil–water separation performance under ultra-low-pressure conditions, with an oil–water emulsion flux of 1121.1 L/m2 h, a recovery rate of 93.1%, and oil rejection as high as 99.2% in the cyclic oil–water emulsion separation process. Meanwhile, the M–PD/PT/2:2 membrane showed excellent stability. Therefore, this work provides a new idea for the preparation of superwetting membranes using dual-biomimetic techniques for effective separation of oil–water emulsion.

Robust super-wetting biaxial polypropylene membrane with multi-scale roughness structures for highly efficient oil/water emulsion separation

The severe toxicity of oily wastewater is considered extremely detrimental to both human health and the environment. Despite previous enormous efforts, it is still challenging to efficiently separate extremely stable micron-sized oils from wastewater emulsion. This study reports a highly mechanically stable biaxial polypropylene membrane with uniform nano-porous structures for excellent separating tiny oil droplets from emulsion. A facile and scalable two-step surface modification method has been developed by employing acrylic acid and sodium hydrogen carbonate monomer. This modification method ensures excellent hydrophilicity (0º) and underwater superoleophobicity (>160º) by constructing multiscale micro/nano rough surfaces with controllable membrane pores. The modified super-wetting membrane efficiently separates micron-sized oil droplets from surfactant-stabilized emulsions with more than 99.5% separation efficiency. Additionally, the membrane’s outstanding mechanical stability ensures excellent recyclability with remarkable wetting constancy to diverse harsh conditions. Inclusively, the simply modified biaxial polypropylene membrane shows noteworthy potential for usage in practical applications.

Fabrication of superhydrophilic mask non-woven fabric with cellulose/GO composite coating for oil/water separation

Superwettable coatings have aroused considerable attention in oil/water separation materials research benefit from their many advantages, such as various preparation methods, high separation efficiency, and low cost. However, many of these coatings are not suitable for practical separation due to the complex composite methods and poor biodegradability. The development of novel superwettable oil/water separation materials with simple fabrication and eco-friendly coating has become a noteworthy target in oil/water separation fields. Since the outbreak of COVID-19, a large number of waste masks abandoned in the natural environments have caused serious environmental hazards. The mask non-woven fabric (MNF) from waste disposable medical masks is a good separation material for its rich microporous. Herein, regenerated degreasing cotton cellulose and graphene oxide (GO) were used to successfully construct an environmentally friendly composite coating on the MNF through a simple dip coating method, and the obtained Cellulose/GO@MNF has excellent superhydrophilicity and underwater superoleophobicity. The fabricated coating possesses favorable chemical stability and nice mechanical strength after being destroyed by corrosive solutions (acid, alkali, salt solution) and physical processing (scratches). Various oil/water mixtures can be separated with high separation efficiency (>98%), and the separation efficiency is absent a substantive drop even after 10 separate cycles. Water can be removed quickly and continuously from the oil/water mixture by the as-fabricated MNF linking with a peristaltic pump. Besides, toluene oil-in-water emulsion can also be separated effectively. What is more significant is that, the Cellulose/GO@MNF fabric fabricated via a simple method and using biodegradable coating materials has potential application prospects in solving both recycling problems of waste masks and oil/water pollution.

In situ preparation of spindle calcium carbonate-chitosan/poly (vinyl alcohol) anti-biofouling hydrogels inspired by shellfish

Hydrogels have received intensive interest in the marine environment due to their excellent anti-biofouling properties. In this work, a series of spindle CaCO3-Chitosan/poly (vinyl alcohol) (SCC/PVA) hydrogels were in situ prepared inspired by the good mechanical self-cleaning and properties of seashell. The morphologies, structure and components of the prepared hydrogels were studied by SEM, FTIR spectra, XRD, TGA, and TEM. The anti-biofouling properties of the prepared hydrogels against protein, bacteria and algae were evaluated by ultrahigh-resolution fluorescence microscopy. Results indicated that chitosan can affect the growth process of CaCO3 leading to the formation of a hollow spindle structure of CaCO3. The prepared SCC/PVA hydrogels have excellent underwater superoleophobicity properties. SCC/PVA-3 hydrogel has the best superoleophobicity property with an underwater contact angle of 167.5°. The compressive strength of SCC/PVA-3 hydrogel is 25 MPa, which is attributed to the doping of SCC. Compared to PVA hydrogel, the settlement of the Navicula, Nitzschia Closterium on the surface of SCC/PVA-3 hydrogels sample decreased by approximately 94 % and 88 %, respectively. The SCC/PVA hydrogels have some antibacterial ability against E. coli. SCC/PVA-3 hydrogel can effectively inhibit the adhesion of elegans with a test time of 180 days in the South China Sea.

Antifouling superhydrophilic porous glass membrane based on sulfobetaine prepared by thiol−ene click chemistry for high-efficiency oil/water separation

Compared to superhydrophobic/superoleophilic membranes for high-efficiency oil/water separation, superhydrophilic membranes displaying underwater superoleophobic properties show improved antifouling performance. Nevertheless, superhydrophilic/underwater superoleophobic surfaces reported so far, in general, are susceptible to oil contamination. In addition, the tricky fabrication methods towards the superhydrophilic membranes also severely limit practical applications of such materials. Herein, we prepared novel superhydrophilic/underwater superoleophobic porous glass membranes with excellent oil fouling resistance via one-step in situ growth of silicone nanofilament network layers on the surface of sand particle-based sintered glass filters using vinyltrichlorosilane (VTCS) as a precursor, followed by grafting of a thiol-functionalized of sulfobetaine by thiol-ene click chemistry. The sulfobetaine-modified porous glass membranes showed excellent underwater superoleophobicity even for viscous crude oil. Besides, such surface-modified glass membranes exhibited high efficiency for the separation of various oil-water mixtures (>99.992%) and oil-in-water emulsions (>99.968%), even for those involved with viscous crude oil (99.982%). Owing to its superior antifouling properties, the sulfobetaine-modified glass membranes display excellent reusability for the separation of oil-water mixtures and oil-in-water emulsions. The outstanding advantages with characteristics of easy-to-fabricate, low-cost, excellent antifouling properties, and high separation performance enable the sulfobetaine-modified porous glass membranes with great potential for oily sewage treatment.

Superwetting Ti3C2TX MXene membranes intercalated with sodium alginate for oil/water separation

Oily wastewater seriously endangers human health. Ti3C2Tx MXene has attracted extensive attention as a building block for separating membranes because of its unique two-dimensional structure and excellent hydrophilicity. In this study, we constructed a superwetting Ti3C2Tx MXene membrane intercalated with sodium alginate. The hydrophilic sodium alginate not only enlarged the nanochannel of the MXene membrane but also decorated the membrane surface and endowed the membrane with excellent surface superwetting properties. The underwater oil contact angle (OCA) was about 151°, indicating an extremely low adhesion between oil and membrane surface. The membrane could also separate a series of oil-water emulsions with high separation efficiency and flux. Due to its excellent underwater superoleophobicity, the membrane demonstrated outstanding antifouling property. Excellent separation performance was maintained even after separation cycles. This work provides insights into the rational use of MXene-based membranes design and demonstrates its potential in the field of membrane separation.

Nanocomposite hydrogel engineered hierarchical membranes for efficient oil/water separation and heavy metal removal

The contaminants of oily sewage and heavy metal ions have been increasingly released into the aquatic environment, which causes a severe threat to both ecosystem and human health. However, it is still difficult to use a single separation technology to effectively deal with such a complex hazardous system to ensure the water safety and environmental remediation. Herein, a novel nanocomposite hydrogel-coated membrane was designed by one-step dip-coating of tannic acid (TA)/sodium alginate (SA)/3-aminopropyltriethoxysilane (APTES) co-depositing strategy, which combines the robust adhesion of TA, the hierarchical architecture induced by APTES and the strong hydration ability of SA. The as-prepared membrane exhibits excellent hydrophilicity and underwater superoleophobicity, which achieves efficient separation for various oil/water emulsions and outstanding anti-oil fouling performance. Meanwhile, the excellent heavy metal adsorption capacity was realized due to the abundant adsorption sites (-COO-, –NH2 and phenolic hydroxyl) and large surface area caused by hierarchical structures. Most interestingly, the fabricated membrane also presented strong chemical stability over a wide pH range 3–11, high salt tolerance and good resistance to anhydrous ethanol corrosion. The designed superwetting membranes show great potential for the purification of oil/water emulsion and the removal of heavy metal ions to effectively remediate the aquatic environment by the concept of ‘killing two birds by one stone’.

Bioinspired Composite Hydrogel‐Coated Stainless Steel Screen for Efficient and Stable Gravity‐Driven Oil–Water Separation

The reasonable and efficient treatment of oily wastewater has attracted wide attention. Herein, a composite hydrogel‐modified filter screen, inspired by fish scales and marine mussels, is prepared via layer‐by‐layer modification to separate oil–water mixture even in harsh environments. First, a stainless steel filter screen is coated by a layer of silicon dioxide (SiO2) microspheres by the vapor deposition of polydimethylsiloxane. Then, a SiO2@polydopamine‐polyacrylamide composite hydrogel (SiO2@P–PGel)‐modified screen is prepared by dipping the screen into a prepolymer solution. Due to the special wettability and micronanostructures, the stable and high efficient water permeation in the air and oil repellency in water are achieved by the screen. A very effective oil–water separation rate of over 99% can be achieved for various types of oil–water mixtures. The separation efficiency and water flux remain stable even after 70 cycles. Another significant feature of the innovative screen is that it displays excellent underwater superoleophobicity in very salty, acidic, and alkaline solutions, suggesting that the screen has excellent oil–water separation performance and stability, even in corrosive aqueous media. This innovative screen is a potentially attractive candidate for the treatment and recovery of oily wastewater due to its high efficiency and stability.

Robust Underwater Oil-Repellent Biomimetic Ceramic Surfaces: Combining the Stability and Reproducibility of Functional Structures.

Robust underwater oil-repellent materials combining high mechanical strength and durability with superwettability and low oil adhesion are needed to build oil-repellent devices able to work in water, to manipulate droplet behavior, etc. However, combining all of these properties within a single, durable material remains a challenge. Herein, we fabricate a robust underwater oil-resistant material (Al2O3) with all of the above properties by gel casting. The micro/nanoceramic particles distributed on the surface endow the material with excellent underwater superoleophobicity (∼160°) and low oil adhesion (<4 μN). In addition, the substrate exhibits typical ceramic characteristics such as good antiacid/alkali properties, high salt resistance, and high load tolerance. These excellent properties make the material not only applicable to various liquid environments but also resistant to the impact of particles and other physical damage. More importantly, the substrate could still exhibit underwater superoleophobicity after being worn under specific conditions, as wear will create new surfaces with similar particle size distribution. This approach is easily scalable for mass production, which could open a pathway for the fabrication of practical underwater long-lasting functional interfacial materials.