Oil-water Separation Materials Research Articles

Stability-enhanced (Cu-, Zn-)MOFs via (Cu, Zn)S composite strategy: A promising approach for oil-water separation

The application of metal-organic frameworks (MOFs) in the field of oil-water separation is developing rapidly, but the challenges of poor water stability, poor scalability and durability still limit its practical application. In this study, two environmentally friendly and non-toxic superhydrophobic (Cu, Zn)S/(Cu-, Zn-)MOFs@stearic acid (CuS/Cu-MOFs@SA and ZnS/Zn-MOFs@SA) coatings were successfully prepared by hydrothermal method combined with dip coating method, with a water contact angle (WCA) of >165°. Through the synergistic effect with stearic acid (SA), the (Cu-, Zn-)MOFs coating composited with CuS and ZnS exhibits excellent durability in extreme environments. This synergistic effect significantly improves the mechanical stability and durability of the coating, allowing it to maintain a WCA of >155° after friction, kneading, tape stripping and ultrasonic treatment. However, CuS/Cu-MOFs@SA coating is significantly superior to ZnS/Zn-MOFs@SA coating in terms of chemical stability (acid-base-salt environment) and self-cleaning ability due to the different ligands used in the preparation process and the formation of particle structure. Significantly improved its durability and reliability in oil-water separation. The separation efficiency of the coating is as high as 98.7 %, and it remains above 97.8 % after 12 times of repeated use. This study provides a new strategy and important reference for the development of superhydrophobic MOFs coatings and oil-water separation materials with high stability, wear resistance and corrosion resistance.

Smart anti‐fouling and self‐repairing polymer brushes for efficient oil–water separation

AbstractThe increasing water pollution problem poses a demand for oil–water separation materials, but preparing separation materials with high efficiency and excellent durability remains a great challenge. In this work, we use a diblock polymer brush of polydimethylsiloxane (PDMS) and poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) based on cotton fabric to prepare oil–water separation membranes with high efficiency, good durability, and intelligent self‐repairing properties. Lubricating PDMS brushes reduces the fouling adhesion due to its low surface energy and high flexibility. pH‐responsive PDMAEMA brushes provide good hydrophobicity and an intelligent self‐repairing effect. The prepared Co‐PDMS‐PDMAEMA has high oil flux (>30,000 L m−2 h−1) and high separation efficiency (>99%) even after 10 cycles and its surface character can be recovered under acidic conditions. Overall, the modified cotton fabric made by such a versatile technique is promising in oil–water separation.

Preparation of ultra-light, highly compressible, and biodegradable chitosan porous materials for heavy metal adsorption, dye adsorption and oil-water separation

Chitosan materials are much important in adsorption, separation and water treatment due to their hydrophilicity, biodegradability and easy functionalization. However, they were difficult to form structural materials, which limited its application in engineering. In this paper, a new type of chitosan porous materials was prepared with two-step strategy involving the freezing crosslinking of chitosan with glutaraldehyde to form cryogels, and their subsequent reduction with NaBH4 to transform CN bonds into CN bonds, resulting in remarkable improvement of mechanical property. That is, the strength remained almost unchanged after 80 % deformation. The abundant -NH2 and -OH on the surface of materials, as well as the unique pore structure from cryogels, gave relatively high adsorption capacity for metals and dyes (88.73 ± 4.25 mg·g−1 for Cu(II) and 3261.05 ± 36.10 mg·g−1 for Congo red). The surface hydrophilicity of materials made it possible for selective water permeation with over 95 % separation efficiency for oil-water mixtures. In addition, simple hydrophobic modification using bromotetradecane achieved selective oil permeation with over 96 % separation efficiency for oil-water mixtures. This study not only provides a new strategy to endow chitosan materials with excellent mechanical property, large adsorption capacity and good oil-water separation performance, but also offers environmentally friendly materials for sewage treatment applications.

Tile roof inspired structure optimization on radial wood to fabricate oil-water separation function

Cross wood was usually selected to fabricate oil-water separation function. However, the cross wood is easy to be deformed after chemical delignification. Therefore, structure optimization via drilling holes on radial wood along with nano Cu(OH)2/CuCl modification overcame the bottleneck defect of dimensional instability, and simultaneously fabricated oil-water separation function. The oil absorption capacity of modified wood increases with the number and depth of drilled holes, reaching a maximum of 3.7 g/g toward dichloromethane. The modified radial wood demonstrated exceptional filtration effectiveness toward dichloromethane/chloroform-water mixtures and exhibited superior photocatalytic degradation capabilities against methylene blue, malachite green, and direct blue 151 dyes. Additionally, the modified radial wood displayed favorable recycle ability for both oil-water separation and photocatalytic degradation. Thus, a facile, cost-effective and environmental friendly strategy proposed in this work has potential to enhance the practical application of wood based oil-water separation materials.

Block copolymer brushes modified cotton fabric for antifouling oil-water separation materials with thermal responsiveness

Polymer brushes have proven to have great potential in oil-water separation but it remains a long-standing challenge to improve their operational stability and service endurance. In this work, we sequentially grafted polydimethylsiloxane (PDMS) and poly (N-isopropylacrylamide) (PNIPAM) brushes on the cotton fabric to prepare a durable and self-reparing oil-water separation film (Co@PDMS/PNIPAM). The grafting of liquid PDMS brushes significantly improved the antifouling performance through its lubricating effect thereby improving the durability. The hydrophilic and thermoresponsive PNIPAM was synthesized through a surface-initiated atom transfer radical polymerization (SI-ARGET ATRP). Co@PDMS/PNIPAM shows high flux in various oily water and bio-solution. More remarkably, Co@PDMS/PNIPAM exhibited intelligent self-repairing characteristics, and this further enhances its stability and service endurance in the application of oil-water separation. The results provide pathways to the preparation of antifouling and durable membranes in the application of water treatment, and resource recovery.

Preparation of lightweight porous slag-based geopolymer highly hydrophobic materials for efficient oil-water separation

Surface hydrophobic modification is a critical technology for enhancing the application properties of materials, crucial for the development of geopolymer materials in oil-water separation. in this study, a lightweight porous slag-based geopolymer highly hydrophobic materials (PSGHHMs) were successfully prepared in-situ using slag and liquid water glass by varying different influencing factors, such as the amount of water/foaming agent/polymethylhydrosiloxane (PMHS) and the curing temperature. The PSGHHMs exhibited high strength, large flux and excellent highly hydrophobic properties, with contact angle reaching 156.14° and a sliding angle of less than 2°. SEM-EDS, TG-DSC and FT-IR analysis reveal that the in-situ modification mechanism of PSGHHMs involves the hydrolysis of Si-H in PMHS under alkaline conditions to form Si-OH. This subsequently reacts with Ca-OH in C-S-H gel to produce Ca-O-Si. Consequently, the PSGHHMs retained their excellent highly hydrophobicity even after calcination at 450℃ for 2.5 h. The PSGHHMs demonstrated robust resistance to acid/alkali/salt corrosion, as well as to friction, with the ability to quickly restore damaged highly hydrophobic properties. Additionally, the PSGHHMs could quickly absorb light/heavy oils, and achieving a desorption efficiency of over 99 %. They were also capable of continuously separation of oil-in-water emulsions and oil-water mixtures. Given these properties, the PSGHHMs have broad potential applications in antifreezing, antifogging, drag reduction and oil-water separation.

A novel Pumice@PVA membrane with high separation efficiency for oil-water emulsion application

Oil pollution poses a major threat to both human health and economic development, and therefore the development and improvement of oil-water separation technology is urgent. Traditional methods have problems such as complicated preparation, high cost and the vulnerability of lipophilic materials to oil contamination. Therefore, finding an inorganic material that meets the requirements of underwater superoleophobic performance and reduces surface modification has become a new demand. In this study, natural pumice was found for the first time to have excellent underwater superoleophobic performance and chemical stability, and the underwater superoleophobic filter membrane was prepared by vacuum adsorption using hydrogen bond cross-linking between natural pumice and PVA. The experimental data show that the prepared PVA/natural pumice ultrafiltration membrane has superhydrophilic and superoleophobic properties, and exhibits excellent stability (OWA>150°) under the harsh environment of strong acid and strong alkali. In addition, the composite membrane has good emulsion separation efficiency (>97 %) and a separation flux of 39.91 Lm-2h-1. It is demonstrated that the composite membrane has oleophobic and wettable properties, and is capable of separating both oil-water mixtures without phase mixing and oil-in-water emulsions without oil contamination. This study provides a new idea for the preparation of superoleophobic materials for oil-water separation, which has the potential for large-scale application.

Sustainable Oily Liquid-Proof Passive Cooling (SOC) Textile for Personal Thermal Management.

Sweat passive-cooling textiles with asymmetric wettabilities on different sides offer an effective and low-energy consumption solution to personal thermal management in extreme thermal environments. However, the sweat-wicking and the cooling abilities decrease when the textile is contaminated by low-surface tension oily liquid fouling. The integration of anti-oily liquid fouling and sweat-wicking abilities on textile involves resolving the contradiction between hydrophilic and oleophobic properties and seeking eco-friendly short-chain fluorides to reduce the surface energy. Herein, a sustainable oily liquid-proof passive cooling (SOC) textile for personal thermal management is proposed. The SOC textile is obtained by applying a fluoride-free hydrophobic coating layer to one side of the high thermal conductive superoleophobic/superhydrophilic basal textile, which is fabricated using eco-friendly short-chain fluoride. The SOC textile preserves the anti-oily liquid fouling property even after 2000 abrasion cycles. Experimental test revealed that the SOC textile exhibits a cooling effect of ≈5°C compared with the cotton textile, and the up to 70% reduction in sweating rate under the constant metabolic heat production rates. The configuration of the SOC textile would inspire the future design of intelligent textiles for personal thermal management, and the proposed strategy have implications for fabrication of eco-friendly oil-water separation materials.

Superelastic, ultralight aramid fibre/tannic acid/graphene nanohybrid aerogel constructed using a cross–scale strengthening strategy for rapid and high–flux oil–water separation

Graphene-based aerogels are efficient oil–water separation materials with enormous potential, but their poor mechanical strength and cycling stability limit their applications. A cross-scale strengthening strategy was used to construct aramid fibre (A)/tannic acid (T)/graphene (G) (ATG) aerogel using an in situ electrostatic self-assembly and freeze-drying process. At 95 % of the ultimate compressive strain, the ATG aerogel could withstand a stress of up to 147 kPa and can rebound quickly. The mechanism for the high mechanical strength of the ATG aerogel was explored by structure characterisation and density functional theory (DFT) calculation. A superhydrophobic aerogel (named H-ATG) was prepared by a hydrophobic modification of ATG using a vapor deposition reaction method. The H-ATG aerogel exhibited excellent superoleophilicity/superhydrophobicity with the oil and water contact angles of 0° and 152.48°, respectively. The hydrophobicity of the H-ATG aerogel was stable over the pH range of 1–13 and the temperature range of -80–600 °C. In addition, the aerogel had an ultra-fast absorption speed and excellent absorption capability, rapidly absorbing various oil-based organic solvents up to 101 times its own weight within 5 s. After the absorption of oil or solvents, it could be easily recovered by combustion, distillation or extrusion, and the performance remained relatively unchanged after 10 cycles. When H-ATG was used as a filter to achieve fast and efficient oil–water separation with a high flux of 20,371.83 L·h−1·g−1. Therefore, the H-ATG aerogel has excellent potential for applications in the oil–water separation and the purification of oily wastewater.

Emulsified oil-water separation properties of superhydrophobic/superoleophilic surface by emulsion droplets impacting dynamic behavior

Superhydrophobic/superoleophilic materials with excellent separation property are urgently needed for the clarification of water from oil-water emulsions, however, the lack of interfacial contact dynamics in the separation process is not beneficial to extensive application for them. Herein, a superhydrophobic/superoleophilic mesh was successfully prepared by spraying fluorinated polyurethane (FPU), silicon dioxide (SiO2) and carbon nanotubes (CNTs). The prepared mesh exhibited excellent superhydrophobic/superoleophilic performance, accomplishing a 1636.9 L m−2h−1 flux and a high separation efficiency above 99.8 % for water-in-oil (W/O) emulsions. The dynamic behavior of emulsion droplets impacting on the prepared mesh was innovatively investigated by experiment and simulation. As the oil content of emulsion droplets increased from 0 wt% to 2 wt%, the maximum spreading diameter (Ddmax) of emulsion droplets decreased from 5.57 mm to 5.28 mm, which can be attributed to the oil capture ability of the superhydrophobic/superoleophilic surface. Simultaneously, the maximum jet height (Hdamx) and the retraction velocity of the droplets firstly decreased and then increased. The results revealed that the oil film captured on the surface possessed good lubricity and water repellency, which could accelerate the dislodging of water from the surface and enhance separation performance. The separation mechanism of superhydrophobic/superoleophilic surface revealed by the contact dynamics study provided a novel path for the fabrication of emulsified oil-water separation materials.

Enhanced separation flux and compressive strength for oil-water separation by adding sodium lignosulphonate

Oil-water separation materials have been deeply developed to solve oil spill problems. However, mechanical strength and separation efficiency remain challenging. Based on the electrostatic repulsion, we design and prepare oil-water separation materials to enhance the separation flux and resistance to pressure by adding sodium lignosulphonate nanoparticles (LSs) to the reduced graphene oxide (rGO), followed by surface modification with trimethoxymethylsilane (MTMS). XRD patterns prove the positive action of LSs for improving interlayer spacing of rGO, which contributes to an excellent separation flux (carbon tetrachloride/water, 43209.71 L⋅m-2⋅h-1) of MLNGA. The compressible recovery ability is enhanced to 49.91 kPa under 80 % strain. The MLNGA presents excellent separation efficiency (∼99.12 %) on a continuous oil-water separation device. All these results indicate the outstanding performances and potential of MLNGA in oil–water separation applications. Moreover, this design concept involves electrostatic repulsion and may be promoted to other anionic macromolecules such as sodium alginate, tannic acid, and pectin.

In-situ construction of stable and efficient superhydrophobic MOFs-based cellulose paper for oil–water separation

In recent years, separating oil-water mixed pollutants has emerged as an increasingly significant part of sustainable development due to oil-containing wastewater discharged and offshore oil spills. Therefore, developing stable and efficient materials for the separation of oily wastewater has garnered significant attention in current research. Herein, a novel superhydrophobic functionalized MOFs-based cellulose paper (PDMS/UiO-66-NH2@CP) was successfully synthesized by integrating cellulose paper (CP) with UiO-66-NH2 via solvothermal method and further modifying with polydimethylsiloxane (PDMS), which was used as an oil-water separation material to purify oily wastewater. The reaction procedure is facile and simple, and the preparation method is efficient. Notably, the as-synthesized PDMS/UiO-66-NH2@CP showed excellent superhydrophobicity/superlipophilicity, with a water contact angle up to 162° and an oil contact angle (OCA) of approximately 0º, and it can still maintain superhydrophobic stability under strong acid or alkali conditions. Furthermore, the surface of superhydrophobic paper cannot been adhered by dye solution and powder, indicating its good self-cleaning and anti-fouling ability. Moreover, the composite paper displayed exceptional UV blocking property with the ability to block 99% ultraviolet. Attributed to these characteristics, PDMS/UiO-66-NH2@CP as an oil-water separator demonstrated exceptional performance in separating oil-water mixtures and emulsions, achieving efficiencies exceeding 98% and fluxes in the range of 105.26−412.14 L·m-2·h-1. More importantly, it displayed remarkable recyclability and its separation efficiency was still above 98% after 50 cycles. This study not only develops a facile and effective strategy for preparing superhydrophobic papers, but also provides innovative and instructive guidance for developing efficient oil-water separation materials.

Green Fabrication of Superhydrophilic/Underwater Superoleophobic Composite Membrane for High-Efficiency Oil/Water Separation in Harsh Environments.

Due to the high oil spill incidence and industrial wastewater discharge including oil and emulsified oil, designing and synthesizing oil-water separation materials which can maintain stability under harsh environmental conditions with high separation efficiencies remains a great challenge. The present work developed an easy, green, cost-effective, and easily scaled-up approach for fabricating cellulose-based membranes. First, we coated polydopamine (PDA) onto fibers of filter membrane (FM). Then, the PDA-FM membrane was immersed into the mixed solution of poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) and further thermally cross-linked at 150 °C to create a superhydrophilic/underwater superoleophobic membrane (PVA/PAA@PDA-FM) to separate oil/water mixtures. The simple thermally cross-linking process promotes multiple covalent chemical bonds generation between cellulose filter membrane, PAA, PDA, and PVA, endowing membranes with excellent stability and resistance to acidity, alkalinity, and salinity. The PVA/PAA@PDA-FM membrane not only demonstrates great separation performance (>99.8%) and great flux (>1000 L m-2 h-1) in oil-water immiscible mixtures but also maintains high separation efficiency under conditions of high acidity, alkalinity, and salinity. Additionally, the PVA/PAA@PDA-FM membrane exhibits excellent separation capacity in oil-water emulsions, which can maintain the >99.6% separation efficiency even after 40 cycles in harsh environments, showing outstanding reusability. Thus, due to the multiple cross-linked networks in the membrane, the excellent performance makes the PVA/PAA@PDA-FM membrane a good application prospect in water purification and oily wastewater treatment.

Utilizing a layer-by-layer self-assembly strategy to construct eco-friendly and sustainable superhydrophobic C–S@PDMS@SiO2 coatings on engineering materials for efficient oil-water separation

In order to mitigate the economic and environmental damage caused by the industrial discharge of oily wastewater, the research and development of efficient and long-lasting oil-water separation devices is imminent. Among them, utilizing the copper stearate (C–S) and hydrophobic SiO2 nanoparticles, a robust superhydrophobic and superoleophilic C–S@PDMS@SiO2 (PDMS shortened form polydimethylsiloxane) was prepared on stainless steel mesh (SSM) using layer-by-layer assembly for heavy oil/water separation. The resulting superhydrophobic surface has a water contact angle of 158° and a water rolling angle of less than 3°. The separation efficiency is as high as 99.78% and a flux is greater than 20,000 L/(m2 × h) after 10 separation cycles for a variety of heavy oil/water mixtures. The superhydrophobic performance of C–S@PDMS@SiO2 SSM is superior to that of the C–S SSM as the modified hydrophobic SiO2 nanoparticles are grafted with long-chain PDMS. The C–S@PDMS@SiO2 SSM exhibited good mechanical and chemical stability. Even under corrosive solution environments (e.g., strong acids, strong bases, and high salt solutions), it was able to separate a variety of immiscible heavy oil/water mixtures with a separation efficiency of greater than 96.5%. In addition, the prepared separation membranes were able to maintain high hydrophobicity after 20 abrasion cycles with 1000 grit sandpaper and still had high separation efficiency. This type of heavy oil/water separation device has a simple preparation process, a sturdy structure, low cost, environmental friendliness, high separation efficiency, and good mechanical and chemical stability, providing a new scheme for the development and wide application.

Polylactic acid/ zinc oxide decorated multi-wall carbon nanotubes fibrous membranes and their applications in oil-water separation

The frequent occurrence of oil spills and oily wastewater leakage has increased the demand for oil-water separation materials with good hydrophobicity. Herein, a novel polylactic acid composite fibrous membrane is reported to address this problem. The zinc oxide decorated multi-wall carbon nanotubes were synthesized via the hydrothermal reaction and composited with polylactic acid to prepare a series of fibrous membranes via electrospinning. The wetting behavior of the prepared fibrous membranes conformed to Cassie's equation, proving that the introduced zinc oxide-decorated multi-wall carbon nanotubes enhanced the surface roughness of the prepared fibrous membranes. Such rough surfaces of the fibrous membranes have enhanced the hydrophobicity and increased the water contact angle to 138.5° (in air) and 159.3° (under oil), respectively. The oil uptake of the prepared fibrous membranes has reached 73.2 g/g. The prepared fibrous membrane was able to absorb oil on the water surface, underwater, or emulsion. Therefore, the prepared polylactic acid/zinc oxide-decorated multi-wall carbon nanotubes fibrous membrane can be a good candidate material for treating oily wastewater.

Preparation of polystyrene and silane-modified nano-silica superhydrophobic and superoleophilic three-dimensional composite fiber membranes for efficient oil absorption and oil-water separation

Oily solid waste and wastewater are two kinds of contaminants that seriously endanger the environment and the general public. Recently, superhydrophobic and superoleophilic materials have attracted extensive attention owing to their exceptional oil-water separation capabilities. In this study, we demonstrated a simple, low-cost, and high-economic efficiency method to prepare nanosilica (SiO2) from dye diatomite filter aid waste (DDW) and silanize it with octadecyltrichlorosilane (OTS) to form hydrophobic nanosilica (hSiO2) by solution impregnation. Polystyrene/hydrophobic nanosilica (PS/hSiO2) composite fiber membranes with a rough surface and low surface energy were prepared by electrospinning. The prepared PS/hSiO2 water contact angle can reach 166.6°, showing superhydrophobicity and excellent adsorption capacity for various common oils. The maximum oil absorption capacity for transformer oil can reach 136.4 g/g. Importantly, the oil absorption process of the nanocomposite is selective, fast, and efficient, and it can be used for the purification of oil-contaminated water. In addition, it also demonstrates remarkable durability and stability in strong acid and alkali solutions. This strategy of making oil-water separation materials from solid waste may offer a straightforward, cost-effective, and environmentally sustainable option for the treatment of solid waste, industrial oil wastewater treatment, and marine oil spill cleanup.

A novel ex-situ method to fabricate pH-responsive material based on core-shell Fe3O4@SiO2 nanoparticles for multi-functional oil-water separation and efficient recycling

The ex-situ method is suitable for the preparation and practical engineering application of large-sized adsorption materials like sponges. pH-responsiveness can solve the post-treatment problem of oil-absorbing sponges. Here, a facile ex-situ method is proposed to construct large-sized multi-functional oil-water separation materials by adsorbing pH-responsive magnetic core-shell structured nanoparticles (MNP) onto different substrates including sponge, metal mesh, and sandpaper. The MNPs are prepared by chemical coating and surface modification. The sponge can achieve in-situ renewable oil-water separation through the "oil absorption - oil desorption" process under different pH values, and the oil droplets exhibit a segmented wiredrawing desorption process. The generated secondary oily wastewater can be further separated through modified metal mesh, which can treat oily wastewater with more complex situations such as oil-water-oil three-phase mixtures. The detached nanoparticles (NP) can be easily recycled and reused through magnets. This method can achieve a large-scale in-situ treatment renewable oil-water separation process that integrates wastewater purification, oil collection, and material regeneration, which is environmentally friendly, energy-saving, and suitable for engineering applications.

A review of various dimensional superwetting materials for oil-water separation.

In recent years, the application and fabrication technologies of superwetting materials in the field of oil-water separation have become a research hotspot, aiming to address challenges in marine oil spill response and oily wastewater treatment. Simultaneously, the fabrication technologies and related applications of superwetting materials have been increasingly diversified. This paper systematically reviews the sources and hazards of oily wastewater and oil-water emulsions, several traditional oil-water separation methods, and their limitations, thereby highlighting the advantages of superwetting materials. Additionally, this paper provides an overview of the fundamental theories of wetting and conducts a microanalysis of the penetration mechanism based on Laplace pressure at the gas-liquid-solid three-phase interface. Following this, the latest advances in superwetting oil-water separation materials are elucidated, focusing on five categories: (i) superhydrophobic-superoleophilic materials; (ii) superhydrophilic-underwater superoleophobic materials; (iii) superhydrophobic-superoleophobic materials; (iv) "special" superwetting materials; and (v) smart switchable superwetting materials. This paper innovatively discusses these materials from the perspectives of two-dimensional and three-dimensional materials, deeply studying the mechanisms of oil-water separation and using data to quantify the separation efficiency. Comparative discussions are conducted on the materials from various dimensions, including different substrates, innovations in existing technologies, and fabrication methods as discussed in various articles, followed by corresponding summaries. Finally, the existing shortcomings and challenges of current superwetting materials are summarized, and prospects are proposed. We firmly believe that developing low-cost, stable, environmentally friendly, and practical large-scale superwetting oil-water separation materials will have broad application prospects and potential in the future.

Activated carbon fibers functionalized with superhydrophilic coated pDA/TiO2/SiO2 with photoluminescent self-cleaning properties for efficient oil-water separation

The adhesion of high-viscosity oil contamination poses limitations on three-dimensional (3D) materials' practical use in treating oilfield-produced water (OPW). In this study, we developed a hybrid pDA/TiO2/SiO2 coating (PTS) on the surface of hydrophilic activated carbon (ACF1) through a combination of dopamine (DA) polymerization, ethyl orthosilicate (TEOS) hydrolysis, and the condensation of TiO2 nanoparticles (NPs) with SiO2 NPs. This coating was designed for gravity-based oil-water separation. The inherent porosity and generous pore size of ACF1-PTS conferred it an ultra-high permeation flux (pure water flux of 3.72 × 105 L∙m−2∙h−1), allowing it to effectively separate simulated oil-water mixtures and oil-water emulsions while maintaining exceptional permeation flux and oil rejection efficiency. When compared to cleaning methods involving ethanol aqueous solutions and NaClO, ultraviolet (UV) illumination cleaning proved superior, enabling oil-contaminated ACF1-PTS to exhibit remarkable flux recovery efficiency and oil-removal capabilities during cyclic separation of actual OPW. Furthermore, the ACF1-PTS material demonstrated impressive stability and durability when exposed to acidic environments (acid, alkali, and salt), robust hydraulic washout conditions, and 25-cycle tests. This study offers valuable insights and research avenues for the development of highly efficient and environmentally friendly 3D oil-water separation materials for the actual treatment of OPW.

Rational designed of PVDF membrane based on surface modification of εPL anchored by PC for crude oil emulsion separation

For high-viscosity wastewater containing crude oil, the membrane material is easily clogged with contaminations, resulting in decreased flux and potentially loss of separation ability. In this study, a superhydrophilic/underwater superoleophobic PVDF membrane (PVDF-PC-εPL) was designed by the self-polymerization of proanthocyanidins (PC) and the grafting reaction of ε-polylysine (εPL), which showed a rough micro-nano structure without adding the inorganic particles. The PVDF-PC-εPL membrane displayed outstanding self-cleaning ability for high-viscosity crude oil, and the separation efficiency of the crude oil-in-water emulsion could be greater than 99.4%. The underwater oil contact angle (UWOCA) of the PVDF-PC-εPL membrane was 165°, after the PVDF-PC-εPL membrane had been exposed to air or water for 6 weeks, or soaked in different pH or seawater for 24 h, the UWOCA remained above 154° and the water contact angle was always 0°. The modification method on the PVDF membrane proposed in this study offers a fresh perspective and choice for preparing the oil-water separation materials.