Immiscible Oil-water Mixtures Research Articles

Enhanced oil/water separation using superhydrophobic nano SiO2-modified porous melamine sponges

Recent advancements in functional sponge materials have garnered significant interest due to their efficacy and cost-effectiveness in oil spill remediation. This study introduces both silane coupling agent (methyltrichlorosilane and 3-aminopropyltriethoxysilane) and nano-SiO₂ particles into the melamine sponge framework via impregnation. Additionally, polydimethylsiloxane (PDMS) serves a crucial role in curing to fuse the substrate with the coating through robust covalent bonds. The modified sponges (SiMAPs) facilitate the formation of rough surfaces comprising hierarchical structures by the deposition of nano-SiO₂ particles, while the silane coupling agents and PDMS contribute to a reduced surface energy. These SiMAP sponges maintain high stability with a water contact angle of 162.6° and demonstrate an adsorption capacity ranging from 40 to 90 times their weight in oil or organic solvents. Furthermore, they achieve a separation efficiency exceeding 98% and an oil flux of 14.38 L/m2∙s in immiscible oil-water mixtures. Additionally, the sorption of trichloromethane reaches 88.1 g/g, and the separation efficiency for surfactant-stabilized emulsions containing diesel is 62.8%. Remarkably, the oil-water separation efficiency surpasses 99.8% in dynamic continuous oil-water separation cycles, as evidenced by 20 experimental trials. These results underscore the substantial potential of SiMAP-modified sponges for addressing oil pollution by enhancing oil-water separation.

Multifunctional superhydrophobic sugarcane bagasse capable of efficiently separating oil-water mixtures and degrading MB

Biodegradable and low-cost superhydrophobic absorption materials are still urgently required for the removal of organic compounds from sewage. In this study, sugarcane bagasse (SCB), an abundant and readily available byproduct from sugarcane industries, was used as substrate to fabricate the superhydrophobic adsorbent through a facile dip-coating technique. Firstly, β-FeOOH particles were in-situ grown on the SCB surface, which was further decorated with SiO2 particles. Next, the modified SCB were coated with benzoxazine based on cardanol and dodecylamine (CD) followed by a thermal curing to obtain a superhydrophobic SCB (PC-D/β-FeOOH@SiO2/SCB) with a water contact angle (WCA) of 154°. PC-D/β-FeOOH@SiO2/SCB not only exhibited excellent oil absorption capacities in the range of 11.8 to 22.6 g/g for various organic solvents and oils, but also could successfully separate immiscible oil-water mixtures and emulsions with a separation efficiency of over 99.1 %. After 30 cycles of use, the absorption capacity of the modified SCB only displayed a slight decrease and its separation efficiencies for immiscible oil-water mixture, water-in-oil and oil-in-water emulsions are all more than 99.2 %, meanwhile, all these repeatedly used SCB still maintained a superhydrophobicity, demonstrating an outstanding reusability. Moreover, the WCA of PC-D/β-FeOOH@SiO2/SCB was still higher than 150o after 48 h of immersion in HCl, NaOH and NaCl solutions, exhibiting a satisfactory chemical stability. Besides, the prepared SCB also possessed a high photocatalytic degradation activity to methylene blue. Therefore, this work not only provides a sustainable and cheap superhydrophobic absorbent for wastewater treatment, but also presents a route for the better utilization of SCB.

Multifunctional lignin-reinforced cellulose foam for the simultaneous removal of oils, dyes, and metal ions from water

Pollutants emitted by industry pose an emerging threat to ecosystems, human health and native species, which has attracted global attention. At present, most of the biomass-based water remediation materials suffer from the poor mechanical properties, complexity of the modification process, single function and low adsorption capacity. Therefore, a high-strength lignin/cellulose foam absorbent (LCMA) with super-hydrophilic surface was developed for wastewater treatment by using lignin as the skeleton to crosslink cellulose through sol-gel method. Combined with an abundance of reactive functional groups and a highly porous structure, LCMA demonstrated a superior absorption and removal performance for cationic dyes and heavy metal ions, with separation efficiencies exceeding 99.76 % for cationic dyes and 99.85 % for heavy metal ions. Further modification of LCMA by a facile method using polydopamine (PDA) and polyethyleneimine (PEI) imparted superhydrophilicity to the foams. The developed LCMA@PDA@PEI exhibited an impressive immiscible oil-water separation performance and emulsion separation performance (Separation efficiency >99.95 % for immiscible oil-water mixtures and >99.05 % for oil-in-water emulsions). With the capabilities of simultaneous removal for dyes, heavy metal ions and oil pollutants from water, LCMA holds a broad application prospect in the water remediation, especially in the treatment of polluted water with complex components.

Continuous and steady-state high-flux demulsification of oil-in-water emulsions by antifouling copper foam with composite superhydrophilicity-oleophobicity

Three-dimensional superhydrophilic materials hardly achieve continuous high-flux demulsification and separation for oil-in-water emulsions due to intrinsic oleophilicity leading to potential penetration of oil droplets through hydration layer and contamination on the surface over long-term separation processes. Constructing intrinsic oleophobic micro-regions on superhydrophilic surface can intensify anti-oil-fouling capacity for three-dimensional superhydrophilic materials. Herein, a composite superhydrophilic-oleophobic copper foam was prepared through co-deposition of aminated and fluorinated carbon nanotubes, skillfully introducing inherent oleophobic micro-regions on superhydrophilic interface to intensify anti-oil-adhesion capacity. Through a column technique, the modified copper foams achieved continuous demulsification of surfactant-stabilized and free oil-in-water emulsions without interruption for cleaning with high fluxes over 6000 and 10,000 L·m−2·h−1, and separation efficiencies over 95.1 % and 97.4 %, respectively. Various emulsions after demulsification transformed into immiscible oil–water mixtures, which can be quickly separated into pure oil and water at the aid of a second-step separation procedure by a superhydrophilic copper mesh. Importantly, the amount of recycled oil was consistent with that in feed emulsion during separation, indicating the accumulated oil in the copper foam could maintain dynamic equilibrium and a continuous and steady-state demulsification was achieved. The high-flux and continuous demulsification represents a significant breakthrough for superhydrophilic materials in the industrial application of oil–water separation.

Bio-inspired superhydrophobic fiber membrane for oil-water separation and non-destructive transport of liquids in corrosive environments

Conventional polymer separation membranes or coatings suffer from poor separation performance and serious failure in highly corrosive environments, due to their low chemical and mechanical stability. Herein, a simple electrospraying and electrospinning strategy was used to prepare flexible superhydrophobic carbon fiber membranes (FSCFM). The wettability of FSCFM was improved by forming a lotus leaf-like hierarchical rough structure on its surface. The FSCFM exhibited an excellent permeation flux of immiscible oil-water mixtures (up to 15,800 L m−2 h−1) and water-in-oil emulsions (over 5500 L m−2 h−1), while the separation efficiencies were always kept at more than 99 % after 25 consecutive separations. Even in corrosive environments, its separation performance did not show any degradation. Notably, except for recovering floating oil under external driving forces with excellent cyclic stabilities, FSCFM was also able to transport various corrosive solutions with high efficiencies (99.9 %). After multiple mechanical damages and bending cycles, the FSCFM remained superhydrophobic. It could also maintain its repellency in strong acids/bases, high salt solutions and even under high-temperature environments (94.5 °C). These superior properties make it a strong candidate for oil-water mixture/emulsion separation and non-destructive transport of highly corrosive fluids.

Facile preparation of superhydrophilic and superoleophobic sand for efficient oil-water separation

Superhydrophilic-superoleophobic materials possess unique advantages in oil-water separation due to their water permeability and oil repellency. In this study, superhydrophilic-superoleophobic sand (CQS) was prepared using a facile and rapid mixing-drying coating method. Quartz sand was modified with polydopamine (PDA) as the hydrophilic binding agent, fluorosurfactant (FS-50) as the oleophobic agent, and CaCO3/SiO2 to construct hierarchical surface roughness. The CQS exhibited a water contact angle of 0° and an oil contact angle of 154°, which resulted in a slightly increased water adhesion capacity and a significantly reduced oil adhesion capacity. Owing to its selective wettability towards oil and water, the CQS was capable of directly separating immiscible oil-water mixtures and oil-in-water emulsions with high separation efficiency (99.5 % and 98.5 %, respectively), driven by gravity. Moreover, immiscible oil/oil mixtures could be effectively separated by the CQS as well, expanding its application to separating immiscible organic liquids with different polarities. Additionally, the CQS demonstrated good reusability and superior stability against acid, alkali, salt, hot water and mechanical abrasion. These properties ensured its applicability in complex environments. The CQS, with exceptional separation capability and stability, holds promising prospects for future applications in related separation field.

Superhydrophobicity PPS@MGFC composite membrane with nanofiber-like structure formed via TIPS and its oil-water separation performance

Oil/ water separation in extreme environments remains a challenging issue, with high requirements for material performance. Polyphenylene sulfide (PPS) has broad application prospects in extreme environments due to its unique performance. In this study, glass fiber cloth (GFC) modified with polydopamine/ phenyltriethoxysilane (PDA/PTES) (hereinafter referred to as MGFC) was used as the support, a superhydrophobic/ superlipophilic PPS nanofiber-like functional layer with low surface energy was prepared via thermally induced phase separation (TIPS) method, (hereinafter referred to as PPS@MGFC composite membrane). Relying on π-π conjugation between PTES and PPS, the composite interface was firmly bonded, effectively enhancing its structural stability. Meanwhile, when the PPS content was 4.2 wt%, the pure-water contact angle reached 156.8°, the oil contact angle reached 0 °. The prepared PPS@MGFC composite membrane showed strong oil-water separation performance in oil-water separation experiments. It could be used to separate various immiscible oil-water mixtures, the water content was less than 150 ppm and flux was higher than 6429 L·m−2·h−1 (gravity drive). For oil-in-water emulsions, the water content was less than 250 ppm, the flux was higher than 2500 L·m−2·h−1 (0.1 bar), and the separation efficiency was higher than 99.9%. In addition, the separation efficiency and flux remained stable in extreme environments and after recycling use. These results indicated that PPS@MGFC composite membrane created in this study has a significant deal of promise for use in the field of oil/water separation.

Tune wastepaper to hydrophobic membranes through metal-ion-induced lignocellulose nanofibril crosslinking for oil-water separation

Herein, we proposed a metal-ion-induced surface nano-engineering technology for transforming hydrophilic waste newspaper (WNP) into a hydrophobic material suitable for oil-water separation, without using hydrophobic chemicals/materials. WNPs were swelled in a dilute ferric ion solution (i.e., 50 mM FeCl3) followed by oven-drying to induce the coordination between ferric ions and hydroxyls of lignocellulose nanofibrils of the paper. This resulted in the crosslinking of lignocellulose nanofibrils and converted the hydrophilic WNP to the hydrophobic membrane (HM). The HM exhibited remarkable oil sorption capacity for various oils, up to 3.4 times its weight, and demonstrated good recyclability after undergoing 10 cycles of absorption-desorption-drying. Additionally, HM demonstrated the ability to effectively separate both immiscible oil-water mixtures and surfactant-stabilized water-in-oil emulsions in continuous gravity-driven oil-water separation processes. With the modification method and advantages in oil-water separation, the as-prepared HM exhibits great potential for application in oil spill treatment and environmental remediation.

Superhydrophobic and robust photothermal/electrothermal PVDF-a/CNT-s@PDMS membrane for crude oil removal and dye adsorption

Recently, the crude oil spill has brought inevitable harm to the global ecological environment. Due to the high-viscosity crude oil, it is wise to take advantage of the photothermal/electrothermal effects of the membrane to separate the crude oil from the water. However, the functional separation membrane always suffers from low photothermal/electrothermal effects and poor stability. Herein, the vinyl polyvinylidene fluoride/mercapto carbon nanotubes@vinyl-terminated polydimethylsiloxane (PVDF-a/CNT-s@PDMS) membrane with fast photothermal/electrothermal effects and organic absorption property was successfully prepared by electrospinning and multi-layer loading method. The prepared PVDF-a/CNT-s@PDMS membrane resisted a variety of liquids and had stable superhydrophobicity (WCA = 156°). Furthermore, the membrane maintained superhydrophobicity even suffer from water and milk under the applied voltage condition. After 100 wear resistance tests, the membrane maintained stable superhydrophobicity and the separation rate remained unchanged. The surface temperature of the membrane rapidly approached to the maximum temperature in 30 s, showing a rapid photothermal/electrothermal effects, and the average separation rate of crude oil was 1185 kg m−2 h−1·bar−1. Meanwhile, the membrane exhibited outstanding efficiency for separate immiscible oil-water mixtures. Importantly, the incorporation of the sulfhydryl group enhanced the special ability of the composite membrane to adsorb organic dyes from oil phase. Therefore, the PVDF-a/CNT-s@PDMS membrane has a wide range of potential application in the domain of oil-water separation.

Converting pomelo peel biowaste into multifunctional sponges integrated underwater superoleophobicity and catalytic ability for sewage treatment

Fabricating practical multitasking materials integrating efficient oil-water separation ability and excellent catalytic performance is significant for water remediation but challenging for substrates and subsequent surface modification causing high cost, high power consumption, and poor reusability. Herein, a multitasking sponge was designed for water purification by successively modifying the biomass pomelo peel (PP) with polypyrrole (PPy), Au nanoparticles (NPs), and polydopamine (PDA). The cost-effective and renewable PP substrates, facile surface decoration of PP with PPy coating, in-situ spontaneous growth of Au NPs, and the protection of the outermost PDA coating endowed the as-obtained PP/PPy-Au/PDA sponges high sewage treatment efficiency and the potential for large-scale preparation. The PP/PPy-Au/PDA sponges exhibited high catalytic reduction activity for 4-nitrophenol (4-NP) and excellent reusability without remarkable decline in catalytic activity even after 10 recycles due to the synergistic effect among PPy, Au NPs and PDA. In addition, this sponge also displayed superior separation efficiency and high filtration flux towards both immiscible oil-water mixtures and O/W emulsions due to its underwater superoleophobicity. Integrating above properties, the PP/PPy-Au/PDA sponge could perform catalytic degradation of organic molecules and meanwhile separation of oil-water mixtures.

Superhydrophobic wrinkled skin grown on polypropylene membranes enhances oil-water emulsions separation

It is urgent to explore new materials having high-efficiency separation performance for oil-water emulsions with low cost in the view of protecting environmental ecology. In this study, a facile procedure, consisting of the anchoring sites insertion tandem with wrinkled skin growth, was developed to manufacture a superhydrophobic wrinkled skin-covered polypropylene (PP) membranes through UV grafting and interfacial polymerization. The monomer octadecyltrichlorosilane (OTS) is immobilized on the amine-group anchoring sites on PP surface through covalent bonding, and the immobilized octadecyl tails facilitate the growth of superhydrophobic wrinkled skin, as characterized by FTIR, XPS and SEM, etc. Such wrinkled skin-covered structure improves the tortuosity of membrane and is beneficial for the membranes to contact with the emulsion fully and strengthen the demulsification effect. The prepared membrane shows superior water repellency and excellent separation performance for both immiscible oil-water mixtures and water-in-oil emulsions containing surfactant, with the retention rate of more than 99%. In addition, the wrinkled skin-covered PP membrane has good resistance to solvents and abrasion resistance due to the strong chemical bonding between the superhydrophobic structure and the PP membranes. Therefore, the newly proposed superhydrophobic wrinkled skin-covered PP membranes have promising practical applications in the field of oil-water separation.

Scalable and switchable CO2-responsive membranes with high wettability for separation of various oil/water systems

Smart membranes with responsive wettability show promise for controllably separating oil/water mixtures, including immiscible oil-water mixtures and surfactant-stabilized oil/water emulsions. However, the membranes are challenged by unsatisfactory external stimuli, inadequate wettability responsiveness, difficulty in scalability and poor self-cleaning performance. Here, we develop a capillary force-driven confinement self-assembling strategy to construct a scalable and stable CO2-responsive membrane for the smart separation of various oil/water systems. In this process, the CO2-responsive copolymer can homogeneously adhere to the membrane surface by manipulating the capillary force, generating a membrane with a large area up to 3600 cm2 and excellent switching wettability between high hydrophobicity/underwater superoleophilicity and superhydrophilicity/underwater superoleophobicity under CO2/N2 stimulation. The membrane can be applied to various oil/water systems, including immiscible mixtures, surfactant-stabilized emulsions, multiphase emulsions and pollutant-containing emulsions, demonstrating high separation efficiency (>99.9%), recyclability, and self-cleaning performance. Due to robust separation properties coupled with the excellent scalability, the membrane shows great implications for smart liquid separation.

Ce-MOF-based superhydrophobic polyurethane sponge reinforced by cellulose for efficient oil-water separation

It is extremely significant to manufacture materials with simple and low-cost synthetic method for the disposal of large-scale oil spills and environmental pollution caused by the illegal discharge of oily wastewater. In this paper, cerium metal-organic framework (Ce-MOF), 1H, 1H, 2H, 2H perfluorodecyltrimethoxysilane (PFOTS) and cellulose were used as raw materials to prepare polyurethane hydrophobic sponges (PU) interconnected by chemical bonds to improve physical properties performance. The sponge shows excellent superhydrophobicity with a surface water contact angle (WCA) of 152.53 ± 0.8°. It has high mechanical strength and oil absorption capacity for various oils/organic solvents up to 15.0–44.9 times its weight. It is more imortant that C–F–Ce@PU can separate immiscible oil-water mixtures driven by vacuum pump or gravity. Superhydrophobic/oleophilic C–F–Ce@PU can also be used to separate water-in-oil emulsions. The above characteristics provide a reference for its practical application in oil-water separation.

Bio-Inspired Eco-Friendly Superhydrophilic/Underwater Superoleophobic Cotton for Oil-Water Separation and Removal of Heavy Metals.

Effective integrated methods for oil-water separation and water remediation have signifi-cance in both energy and environment fields. Materials with both superlyophobic and superlyophilic properties toward water and oil have aroused great attention due to their energy-saving and high-efficient advantages in oil-water separation. However, in order to fulfill the superlyophobicity, low surface tension fluorinated components are always being introduced. These constituents are environmentally harmful, which may lead to additional contamination during the separating process. Moreover, the heavy metal ions, which are water-soluble and highly toxic, are always contained in the oil-water mixtures created during industrial production. Therefore, material that is integrated by both capacities of oil-water separation and removal of heavy metal contamination would be of significance in both industrial applications and environmental sustainability. Herein, inspired by the composition and wettability of the shrimp shell, an eco-friendly chitosan-coated (CTS) cotton was developed. The treated cotton exhibits the superhydrophilic/underwater superoleophobic property and is capable of separating both immiscible oil-water mixtures and stabilized oil-in-water emulsions. More significantly, various harmful water-soluble heavy metal ions can also be effectively removed during the separation of emulsions. The developed CTS coated cotton demonstrates an attractive perspective toward oil-water separation and wastewater treatment in various applications.

Superhydrophobic polyurethane sponge based on sepiolite for efficient oil/water separation

Massive oil leakage accidents and illegal discharge of oily wastewater have not just destroyed the sustainability of the ecological environment but caused permanent damage to marine ecosystems, which makes it urgent to handle it. In this paper, by means of sol-gel, micro-nan silica that grew from the surface of fibrous sepiolite was organically modified with 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane (PFDS). The superhydrophobic sepiolite/silica firmly attached to the surface of polyurethane sponge under the action of oily epoxy resin with strong adhesion. The sponge exhibited superhydrophobicity and excellent selective oil adsorption capacity (19.98–40 times of their own weight). More importantly, besides the effective separation of immiscible oil-water mixtures (the separation rate reached 98.72%), it could also efficiently separate oil with water and oil with salt solution emulsions. In addition, the sponges kept hydrophobic even after floating in extremely corrosive liquids for 20 h, showing a strong resistance to strong acidic as well as alkaline liquids. After 100 times of mechanical compression, the three-dimensional structure of sponge held still and the water contact angle was greater than 144°, demonstrating an excellent mechanical stability, which provided a reference for its practical application in oil-water separation.

Facile Fabrication of Electrospun Nanofibrous Aerogels for Efficient Oil Absorption and Emulsified Oil-Water Separation.

Developing superabsorbents for efficiently separating immiscible oil–water mixtures and oil–water emulsions are highly desirable for addressing oily wastewater pollution problems, but it remains a challenge. Ultralight nanofibrous aerogels (NFAs) with unique wetting properties show great potential in oily wastewater treatment. In this study, a facile and efficient method for producing hierarchical porous structured NFAs with hydrophobicity for high efficiency oil–water separation was developed. The synthesis included three steps: wet electrospinning, freeze drying, and in situ polymerization. The obtained NFA demonstrated outstanding oil absorption capacity toward numerous oils and organic solvents, as well as efficient surfactant-stabilized water-in-oil emulsion separation with high separation flux and excellent separation efficiency. Furthermore, these NFAs displayed excellent corrosion resistance and outstanding recoverability. We assume that the resultant NFAs fabricated by this facile strategy are highly promising as ideal oil absorbents for practical oily wastewater treatment under harsh conditions.

Robust and Durable Superhydrophobic Polythiophene/SiO2 Coated Cotton Fabric for Versatile Oil–Water Separation

AbstractWith the development of industrialization, environmental pollution problems (e.g., oily water discharge and oil spill accidents) are becoming increasingly severe. The efficient and economic treatments for oily sewage are urgently needed and remain a huge challenge. Here, a robust and durable superhydrophobic material with the contact angle above 160° is prepared by coating SiO2 particles/polythiophene on cotton fabrics through a sol–gel process and an oxidation coupling polymerization. The polythiophene/SiO2 coated cotton fabric displays excellent resistance to ultraviolet irradiation, high and low temperatures, acid and salt solution immersion, organic solvent immersion, and good mechanical abrasion durability, antidirt and antifrost properties. The modified fabric is successfully applied as a filter to separate oil–water mixtures by gravity with high separation efficiency and excellent reusability. Moreover, superhydrophobic absorbers can be easily prepared from common 3D porous materials such as a sponge wrapped with the modified fabric for the effective collection of oil. Both immiscible oil–water mixtures and emulsions (oil‐in‐water and water‐in‐oil) can be separated even under harsh conditions (acidic solution or artificial seawater). This work provides a facile and selectable solution to treat oily sewage and leads to new ways of efficient oil–water separation.

Carbon Nanotubes and Polydopamine Modified Poly(dimethylsiloxane) Sponges for Efficient Oil-Water Separation.

In this paper, effective separation of oil from both immiscible oil–water mixtures and oil-in-water (O/W) emulsions are achieved by using poly(dimethylsiloxane)-based (PDMS-based) composite sponges. A modified hard template method using citric acid monohydrate as the hard template and dissolving it in ethanol is proposed to prepare PDMS sponge composited with carbon nanotubes (CNTs) both in the matrix and the surface. The introduction of CNTs endows the composite sponge with enhanced comprehensive properties including hydrophobicity, absorption capacity, and mechanical strength than the pure PDMS. We demonstrate the successful application of CNT-PDMS composite in efficient removal of oil from immiscible oil–water mixtures within not only a bath absorption, but also continuous separation for both static and turbulent flow conditions. This notable characteristic of the CNT-PDMS sponge enables it as a potential candidate for large-scale industrial oil–water separation. Furthermore, a polydopamine (PDA) modified CNT-PDMS is developed here, which firstly realizes the separation of O/W emulsion without continuous squeezing of the sponge. The combined superhydrophilic and superoleophilic property of PDA/CNT-PDMS is assumed to be critical in the spontaneously demulsification process.

Multifunctional alginate-based carbon aerogels for oil–water mixture and emulsion separation

Efficient separations of both water-in-oil (W/O) and oil-in-water (O/W) emulsions are still challenging. In this study, a alginate-based carbon aerogel (AB carbon aerogel) as oil-water separation materials were prepared by wet spinning, high-temperature carbonization, and acidification, which were characterized using scanning electronic microscopy (SEM), energy-dispersion spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and oil and water contact angle. AB carbon aerogel revealed multifunctional separations of immiscible oil-water mixtures and emulsifier-stabilized W/O and O/W emulsions. The separation fluxes and separation efficiencies were 131 L m−2 h−1 and 99.02% for water-in-CCl4 emulsion, and were 94 L m−2 h−1 and 98.97% for n-hexane-in-water emulsion, respectively. The multifunction of AB carbon aerogel is due to the amphiphilicity.

A facile route for the fabrication of a superhydrophilic and underwater superoleophobic phosphorylated PVA-coated mesh for both oil/water immiscible mixture and emulsion separation

Special wettable materials have been shown to be promising for use in oil-water separation and, in particular, hydrogel-based materials have been studied for water separation from oil-water mixtures due to their high hydrophilicity. Here, a superhydrophilic and underwater superoleophobic phosphorylated PVA (PPVA) hydrogel-coated stainless-steel mesh with underwater oil repellency was prepared using a simple and facile route that introduced metal ions for PVA crosslinking. The PPVA hydrogel-coated mesh can not only separate immiscible oil-water mixtures but also separate surfactant-stabilized oil-in-water emulsions with a high separation efficiency (>99.2%). In addition, due to its multiple crosslinked networks, the resultant PPVA hydrogel-coated mesh exhibited good chemical stability and wear resistance and can tolerate high acid, alkali, salty and organic solvents.