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Three-dimensional (3D) porous absorbents have attracted significant attention in the oily wastewater treatment technology due to their high porosity and elasticity. Given their amphiphilic surface, they have a propensity to simultaneously absorb water and oil, which restricts their range of applications. In this study, a reduced graphene oxide and titanium dioxide nanocomposite (rGO/TiO2) was used to fabricate an ultrahydrophobic melamine sponge (MS) through interfacial modification using a solution immersion technique. To further modify it, polydimethylsiloxane (PDMS) was grafted onto its surface to establish stronger covalent bonds with the composite. The water contact angle of the sponge (rGO/TiO2/PDMS/MS) was 164.2°, which satisfies the condition for ultrahydrophobicity. The evidence of its water repellency was demonstrated by the Cassie–Baxter theory and the lotus leaf effect. As a result of the increased density of rGO/TiO2/PDMS/MS, it recorded an initial capacity that was 2 g/g lower than the raw MS for crude oil absorption. The raw MS retained 53% of its initial absorption capacity after 20 cycles of absorption, while rGO/TiO2/PDMS/MS retained 97%, suggesting good recyclability. Excellent oil and organic solvent recovery (90%–96%) was demonstrated by rGO/TiO2/PDMS/MS in oil–water combinations. In a continuous separation system, it achieved a remarkable separation efficiency of 2.4 × 106 L/(m3·h), and in turbulent emulsion separation, it achieved a demulsification efficiency of 90%–91%. This study provides a practical substitute for massive oil spill cleaning.

Cellulose nanofibers (CNFs) have attracted widespread attention for their capability of producing biodegradable, environmentally safe separation membranes for sustainable water pollution treatment. However, the low mechanical strength and poor corrosion resistance prevent CNF membranes from providing long-lasting wetting stability and separation stability, resulting in poor oil/water emulsion separation efficiency. Herein, a dual structural enhancement strategy of calcium ion (Ca2+)-crosslinking and phytate modification was innovatively presented to fabricate CNF composite membranes with long-lasting wetting stability and mechanical stability for stabilized emulsion separation. Introducing Ca2+ into the fiber crosslinking system provides additional crosslinking paths to facilitate interfacial regulation while structurally strengthening of CNF composite membranes by calcium phytate formed in the phytate modification. Benefiting from this enhancement strategy, the obtained membrane exhibited excellent mechanical strength and stability, with low-stress losses when soaked in different solutions or solvents. Meanwhile, the membrane demonstrated outstanding water-wetting behavior and wetting selectivity of super-hydrophilicity and underwater superoleophobicity with an underwater oil contact angle of 152.83°, allowing for efficient separation of oil-in-water emulsions. The experimental results demonstrated that the membrane can successfully separate two representative oil/water mixtures, including surfactant-free oil-in-water emulsions (SFEs) and surfactant-stabilized oil-in-water emulsions (SSEs), displaying higher separation efficiency (99.2%) and separation fluxes (over 1000 L·m−2·h−1) for SSEs. Additionally, the membrane exhibited positive stability and recycling performance, which possesses an excellent potential for the effective and continuous separation of water-in-oil emulsions. Based on the interfacial design and structural modulation, this study offers an efficient path for developing CNF-based membranes with reinforced structures. [ABSTRACT FROM AUTHOR]

In order to achieve efficient and durable oil-water emulsion separation, the membranes possessing high separation efficiency and mechanical strength attract extensive attention and are in great demand. In present study, a kind of polytetrafluoroethylene (PTFE)-based bilayer membrane was fabricated by electrospinning fibrous PTFE (fPTFE) on an expanded PTFE (ePTFE) substrate. The morphological observation revealed that the fibrous structure of the fPTFE layer could be tailored by controlling the formulation of spinning solution. The addition of appropriate polyoxyethylene (PEO) would make the fibers in the fPTFE layer finer and more uniform. As a result, the compounded membrane exhibited a small pore size of approximately 1.25 µm and a substantial porosity nearing 80%. This led to super-hydrophobicity, characterized by a high water contact angle (WCA) of 149.8°, and facilitated rapid oil permeation. The water-in-oil emulsion separation experiment further confirmed that the compounded membrane not only had a high separation efficiency closing 100%, but such an outstanding separation capacity could be largely retained, either through multiple cycles of use or through strong acid (pH=1), strong alkali (pH=12), or high-temperature (100 °C) treatment. Additionally, the mechanical behavior of the bilayer membrane was basically contributed by that of each layer in terms of their volume ratio. More significantly, the poor creep resistance of fPTFE layer was suppressed by compounding with ePTFE substrate. Hence, this study has laid the groundwork for a novel approach to create PTFE-based compounded membranes with exceptional overall characteristics, showing promise for applications in the realm of emulsion separation. [ABSTRACT FROM AUTHOR]

Janus membrane materials have received widespread attention in oily wastewater due to their special wettability and high selectivity, however, the poor structural stability and weak mechanical properties of membrane significantly restrain the practical application. Herein, cellulose was used as the membrane matrix and modified with dopamine as the hydrophilic modifier and adhesive to obtain a polydopamine/cellulose superhydrophilic membrane (PDA/CM). Secondly, the polyethylene terephthalate (PET) electrospinning solution prepared from waste Coca-Cola bottles was used to electrospin PET membrane on the surface of PDA/CM superhydrophilic membrane to form hydrophobic PET layer, and finally obtained PET/PDA/CM Janus membrane with asymmetric wetting properties. The PDA/CM membrane side exhibits superhydrophilicity, which can separate various oil-in-water emulsions with efficiency of above 98%. Oppositely, the PET side owns hydrophobicity, which can separate various water-in-water emulsions with efficiency of above 98.7%. After 10 cycles, the separation efficiency remained over 98.6% for oil-in-water emulsions and 98.5% for water-in-oil emulsions, demonstrating its good recycling ability. Moreover, compared with the original cellulose membrane, the obtained Janus membrane has stronger mechanical properties, and because PDA acts as a structural adhesive between the two layers, the membrane does not delaminate during the mechanical stretching process. This study provides a novel strategy for design stability structure and enhanced mechanical ability of Janus membrane toward oily wastewater purification in the future. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Transactions B: Applications is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herein, the concept of a membrane‐equivalent foam (MEF) with equivalent characteristics to a separated multilayer membrane is proposed and elaborated to mitigate the conflict between efficiency and selectivity in emulsion separation. Porous polytetrafluoroethylene/carbon (PTFE/C) composite MEF with a two‐level microporous structure (bubble pores and ice‐templated pores) was prepared successfully, derived from a PTFE/glutaraldehyde crosslinked polyvinyl alcohol (PVAG) composite foam green body. The PVAG‐based in situ carbon was analyzed as composed mainly of amorphous carbon. The bubble pores were observed to be interconnected by ice‐templated pores. The porosity of the porous PTFE/C composite MEF reached a remarkable value of 73.35%. Corresponding to m(PTFE)/m(PVA) values of 14/1, 12/1, 10/1 and 8/1, the average pore sizes of the bubble pores were 32.99, 44.31, 47.33 and 48.01 μm, and the average sizes of the ice‐templated pores were about 2.24, 2.77, 3.02 and 3.47 μm, respectively. Meanwhile, the porous PTFE/C composite MEF exhibited near superhydrophobicity in air and superhydrophobicity under oil. In gravity‐driven water−oil emulsion separation tests, the oil flux was up to 3541 L h−1 m−2 and the separation efficiency reached more than 99.52%. After 20 cycles of testing, the oil flux and separation efficiency remained stable. The membrane‐equivalent thickness of the samples from PTFE/C‐m1 to PTFE/C‐m4 were below 3.47, 4.26, 0.58 and 0.30 nm, respectively, which is about 10−7–10−6 times lower than the height of porous PTFE/C composite MEF. It is reasonable to believe that porous PTFE/C composite MEF could effectively mitigate the 'trade‐off' effect. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Oil/water separation processes have garnered significant global attention due to the quick growth in industrial development, recurring chemical leakages, and oil spills. Hence, there is a significant demand for the development of inexpensive superwetting materials in an eco-friendly manner to separate oil/water mixtures and emulsions. In this study, a superwetting melamine sponge (SMS) with switchable wettabilities was prepared by modifying melamine sponge (MS) with sodium dodecanoate. The as-prepared SMS exhibited superhydrophobicity, superoleophilicity, underwater superoleophobicity, and underoil superhydrophobicity. The SMS can be utilized in treating both light and heavy oil/water mixtures through the prewetting process. It demonstrated fast permeation fluxes (reaching 108,600 L m−2 h−1 for a light oil/water mixture and 147,700 L m−2 h−1 for a heavy oil/water mixture) and exhibited good separation efficiency (exceeding 99.56%). The compressed SMS was employed in separating surfactant-stabilized water-in-oil emulsions (SWOEs), as well as surfactant-stabilized oil-in-water emulsions (SOWEs), giving high permeation fluxes (reaching 7210 and 5054 L m−2 h−1, respectively). The oil purity for SWOEs' filtrates surpassed 99.98 wt% and the separation efficiencies of SOWEs exceeded 98.84%. Owing to their remarkable capability for separating oil/water mixtures and emulsions, eco-friendly fabrication method, and feasibility for large-scale production, our SMS has a promising potential for practical applications. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramic membranes have gained increasing attention due to their excellent chemical and thermal stability serving in harsh conditions. However, the use of SiC ceramic membrane is limited in micro-filtration fields because of the micro-scale pores in the selective layer. Here, a pure-SiC ultrafiltration (UF) membrane was prepared by dip-coating and recrystallization sintering using fine SiC particles of 100 nm and 50 nm in sizes. EDS and XRD analysis confirmed that the membrane was composed of pure-SiC phase, which endowed the UF membrane with strongly chemical resistance. Because of the refinement in particles, the average pore sizes of the ceramic membrane made of 100 nm and 50 nm particles corresponded to 82 nm and 58 nm, respectively. Due to the refinement in pore size, the oil flux increased from 69.50 L/(m2·h) to 99.01 L/(m2·h) and the oil rejection exceeded 98.8 % for the 50 nm membrane. [ABSTRACT FROM AUTHOR]

Metal organic framework (MOF)-derivatives have a larger specific surface area, higher porosity, tunable pore size, higher conductivity, good stability, more exposed active species, etc., but few literature are reported about their application potential in micropollutant separation and removal. In view of this, a robust MOF derivative-based photocatalytic superhydrophobic membrane (D6/TiO2/MoS2/NiCo-NC/PVDF) was successfully fabricated for the first time through solvothermal synthesis and chemical modification, combined with a negative pressure-assisted loading approach. (1) The MoS2-doping strategy effectively avoided the collapse and coarsening of cauliflower-like MOFs during the calcination phase and simultaneously ensured the uniform distribution of metal particles in MOF-derived carbons. (2) The synergistic catalysis of the NiCo-MOF derivative, MoS2, and TiO2 enhanced the transfer efficiency of electrons and free radicals, achieving efficient in situ degradation of pesticides and pharmaceutical and personal care products. (3) The introduction of sodium alginate greatly improved the adhesion between the coating and polyvinylidene fluoride (PVDF) membrane and simultaneously enhanced the growth of MOFs through complexation. (4) The cauliflower-like MOF-derived carbon skeleton with higher surface areas and micronanoporosity combined with a heterogeneous MoS2 structure provided a large specific surface area and enough adsorption sites for various pollutants. High thermal calcination treatment greatly enhanced MOF growth rate, thus resulting in a flaky structure with high regularity and a large specific area. (5) The ultralow surface energy of interlaced siloxane molecules endowed the hybrid membrane with robust superhydrophobicity and superoleophilicity, always maintaining superhydrophobicity after long-time photodegradation. The final membrane achieved continuous emulsion separation and a photocatalytic self-cleaning property. The separation efficiency of the hybrid membrane for emulsions was still up to 97% after reuse for 120 cycles, and it could degrade 86.5% PRO, 90.1% ACE, 92.1% ASP, and 94.3% SMZ, respectively, with the initial concentration of 10 mg/L. The driving forces for oil–water separation and decontamination of the D6/TiO2/MoS2/NiCo-NC/PVDF membrane mainly involved the grasping forces of dodecamethylcyclohexasiloxane, capillary force of inner pores, electrostatic interaction, hydrogen bond interaction, partial p-π conjugation, van der Waals force, and lipophilicity. [ABSTRACT FROM AUTHOR]

Superwetting membranes have superior advantages in the treatment of oil contaminated wastewater, especially when it is in an emulsified state. However, these types of membranes suffer from size-sieving limitations. Here, a Janus membrane was constructed by integration of superhydrophobic/underwater superoleophilic and superhydrophilic/underwater superoleophobic fabrics. Under gravity induced flow, water rapidly passes from the superhydrophobic to the superhydrophilic sides of this membrane while oil droplets are retained by the superwetting interface via an “attraction-aggregation-coalescence” process, realizing highly efficient emulsion separation. [ABSTRACT FROM AUTHOR]

Although membrane separation technology has been widely used in the treatment of oily wastewater, the complexity and high cost of the membrane preparation, as well as its poor stability, limit its further development. In this study, via the vacuum-assisted suction filtration method, polydopamine (PDA)-coated TiO2 nanoparticles were tightly attached and embedded on both sides of laboratory filter paper (FP). The resultant FP possessed the typical wettability of high hydrophilicity in the air with the water contact angle (WCA) of 28°, superoleophilicity with the oil contact angle (OCA) close to 0°, underwater superoleophobicity with the underwater OCA greater than 150°, and superhydrophobicity under the water with the underoil WCA over 150° for five kinds of organic solvents (carbon tetrachloride, toluene, n-hexane, n-octane, and iso-octane). The separation efficiency of immiscible oil/water, oil-in-water, and water-in-oil emulsions using the modified FP is higher than 99%. After 17 cycles of emulsion separation, a high separation efficiency of 99% was still maintained for the FP, along with good chemical and mechanical stability. In addition, successful separation and purification were also realized for the oil-in-water emulsion that contained the methylene blue (MB) dye, along with the complete degradation of MB in an aqueous solution under UV irradiation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Emulsified oil leakage onto the bulk water surface causes severe issues on global ecology and health. Developing efficient, rapid, and universal separation methods of emulsions has been a significant topic in scientific studies. However, a contactless and additive‐free strategy to achieve continuous floating emulsion separation and oil collection remains to be discovered. Herein, a universal contactless demulsification, transportation, and collection method to dispose floating emulsions by ionic wind, which contains active charged particles generated by corona discharge is reported. The splash‐like demulsification process of floating emulsions is attributed to the rupture of water film enveloped on oil droplet surface, simultaneously and respectively. The evidence of this process recorded by a high‐speed camera with 20 000 fps has a referential significance for other works. This study may clean up universal floating emulsions discharged on water in real situations such as oil stations, chemical plants, and restaurants, and furthermore increase the potential of remote control in liquid dynamics by corona discharge. [ABSTRACT FROM AUTHOR]

The high internal phase emulsion (HIPE) template method is widely used to prepare porous functional materials because of its designable emulsion components and adjustable porosity. Herein, amphiphilic gelatin (GE) as the sole emulsion stabilizer, and no additional emulsifiers were added to prepare a stable GE‐HIPE membrane and its zeolitic imidazolate framework‐67 (ZIF‐67) hybrid composite membrane. The ZIF‐67/GE‐HIPE composite membrane has good lipophilicity by constructing dual micro‐nano structures by HIPE template and in situ growth of ZIF‐67. When ZIF‐67 was grown in situ, the water contact angle (CA) increased from 58.1 ± 2° for the GE membrane to 121 ± 1.9° for ZIF‐67/GE‐HIPE composite membranes. Besides, the minimum CA of organic solvent is 4.5 ± 0.7° (n‐hexane). The ZIF‐67/GE‐HIPE composite membranes exhibit good O/W emulsion separation properties and adsorption removal ability of organic pollutants. After 10 times of recycling emulsion separation, the emulsion separation capacity of the membrane was still greater than 99.4%. The lipophilic dye removal rate of the ZIF‐67/GE‐HIPE composite membrane was 2.37 times higher than that of GE‐HIPE, and the adsorption process conforms to the pseudo‐second‐order model. Thus, this work provides a strategy for the preparation of GE‐based hydrophobic modified membrane and also presents a typical treatment of adsorption‐separation of lipophilic substances. [ABSTRACT FROM AUTHOR]

Oil/water separation processes have garnered significant global attention due to the quick growth in industrial development, recurring chemical leakages, and oil spills. Hence, there is a significant demand for the development of inexpensive superwetting materials in an eco-friendly manner to separate oil/water mixtures and emulsions. In this study, a superwetting melamine sponge (SMS) with switchable wettabilities was prepared by modifying melamine sponge (MS) with sodium dodecanoate. The as-prepared SMS exhibited superhydrophobicity, superoleophilicity, underwater superoleophobicity, and underoil superhydrophobicity. The SMS can be utilized in treating both light and heavy oil/water mixtures through the prewetting process. It demonstrated fast permeation fluxes (reaching 108,600 L m−2 h−1 for a light oil/water mixture and 147,700 L m−2 h−1 for a heavy oil/water mixture) and exhibited good separation efficiency (exceeding 99.56%). The compressed SMS was employed in separating surfactant-stabilized water-in-oil emulsions (SWOEs), as well as surfactant-stabilized oil-in-water emulsions (SOWEs), giving high permeation fluxes (reaching 7210 and 5054 L m−2 h−1, respectively). The oil purity for SWOEs’ filtrates surpassed 99.98 wt% and the separation efficiencies of SOWEs exceeded 98.84%. Owing to their remarkable capability for separating oil/water mixtures and emulsions, eco-friendly fabrication method, and feasibility for large-scale production, our SMS has a promising potential for practical applications.

Silica nanorods modified fiber membranes were successfully fabricated for the separation of emulsions by filtration deposition method. Compared to the unmodified membranes, the arithmetic mean and root mean square of the membranes were 5.69 μm and 9.71 μm, with an improvement of 39.8% and 46.0%, respectively. Roughness increases improved hydrophilicity and underwater oleophobicity of the membrane. The instantaneous water contact angle (WCA) and underwater oil contact angle (UOCA) reached 0° and 151.92°, showing excellent superhydrophilic and underwater superoleophobic properties. The structural stability of the membranes was demonstrated by testing the mass and microstructural changes after continuous ultrasonic treatment, where the mass loss was only 5.42% and no significant changes in the microstructure were observed. Moreover, following immersion treatment with acid, alkali, and saline solutions, the maximum loss of membrane mass was only 1.20% and it remained underwater oleophobic, displaying excellent chemical stability. The separation efficiency of the silica nanorods modified fiber membrane for oil-in-water emulsions was as high as 96%, and the separation flux was above 1900 L m−2 h−1·bar−1. The separation efficiency of the membranes was consistently maintained above 96% for 5 cycles. [ABSTRACT FROM AUTHOR]

Developing a straightforward and effective hydrophobic modification for metal−organic frameworks (MOFs) under mild conditions is meaningful for MOF applications. Here, a post‐synthetic modification approach assisted with metal hydroxyl groups at room temperature is reported to induce hydrophobicity in the hydrophilic UiO‐66. The bonding between Zr−OH in UiO‐66 and n‐tetradecylphosphonic acid (TDPA) is the vital force for the modifier TDPA. Superhydrophobic and superoleophilic composites were constructed for efficient oil‐water separation by coating TDPA‐modified UiO‐66 (P‐UiO‐66) on commercial melamine sponges (MS) and filter papers (FP) with water contact angles of 153.2° and 155.6°, respectively. The P‐UiO‐66/MS composite could quickly and selectively absorb oily liquids up to 43 times its weight from water. The P‐UiO‐66/MS achieved continuous oil collection with high separation efficiencies (≥99.4 %). In addition, P‐UiO‐66/FP and P‐UiO‐66/MS showed high separation efficiencies for water‐in‐oil emulsions (≥98.5 %) and oil‐in‐water emulsions, respectively, with high resistance to low/high temperatures and acid/base conditions. The metal hydroxyl group‐assisted post‐synthetic modification strategy offers a facile and broad way to prepare hydrophobic MOFs for promising applications in environmental fields. [ABSTRACT FROM AUTHOR]

Although many superwetting materials have been designed for the treatment of oil-containing wastewater, separation strategies for oil-in-water systems containing bacteria have rarely been reported. Herein, poly(vinylidene difluoride)- and poly(lactic acid)-blended fibrous membranes loaded with silver and copper oxide nanoparticles were successfully prepared by a two-step method of electrostatic spinning and liquid-phase synthesis. The product membrane showed excellent super-oleophilic properties in air and hydrophobicity under oil. It could separate water-in-oil emulsion systems containing surfactants with an efficiency above 90%. More importantly, the nanoparticle-loaded fibers were characterized by material degradability and slowly released ions. The fibers exhibited excellent antibacterial activities against both gram-positive and -negative bacteria. This work provides a feasible strategy for water-in-oil emulsion separation and bacterial treatment of wastewater. [ABSTRACT FROM AUTHOR]

Smart surfaces with responsive wettability are unstable, and depend upon continuous external stimuli, which limits their widespread application in switchable oil/water emulsions separations. In this study, a Ti‐based 3D porous structure (SLM‐3DTi) is printed using advanced selective laser melting (SLM) technology for the switchable separation of oil/water emulsion. With the assistance of the computer program, porous structure and re‐entrant texture can be easily designed and printed in one step. Without any continuous external stimulus, the wettability of SLM‐3DTi can be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing cycles. The SLM‐3DTi achieves switchable surfactant‐stabilized oil‐in‐water emulsion (SSE(o/w)) and surfactants‐stabilized water‐in‐oil emulsion (SSE(w/o)) separation with purity above 99.8% at a flux of more than 2000 L m−2 h−1. In addition, the re‐entrant texture of the SLM‐3DTi surface is formed with the partially melting powder particles on the part contour, which has much stronger mechanical durability than any binder. Furthermore, SLM‐3DTi has excellent corrosion resistance due to the material properties of Ti. More importantly, based on the visualization analysis of the simulation, the mechanism of SLM‐3DTi emulsion separation is further elucidated. Therefore, SLM‐3DTi has broad practical application potential for high‐flux, high‐purity, and switchable oil/water emulsion separation. [ABSTRACT FROM AUTHOR]

Although membrane separation technology has been widely used in the treatment of oily wastewater, the complexity and high cost of the membrane preparation, as well as its poor stability, limit its further development. In this study, via the vacuum-assisted suction filtration method, polydopamine (PDA)-coated TiO2 nanoparticles were tightly attached and embedded on both sides of laboratory filter paper (FP). The resultant FP possessed the typical wettability of high hydrophilicity in the air with the water contact angle (WCA) of 28°, superoleophilicity with the oil contact angle (OCA) close to 0°, underwater superoleophobicity with the underwater OCA greater than 150°, and superhydrophobicity under the water with the underoil WCA over 150° for five kinds of organic solvents (carbon tetrachloride, toluene, n-hexane, n-octane, and iso-octane). The separation efficiency of immiscible oil/water, oil-in-water, and water-in-oil emulsions using the modified FP is higher than 99%. After 17 cycles of emulsion separation, a high separation efficiency of 99% was still maintained for the FP, along with good chemical and mechanical stability. In addition, successful separation and purification were also realized for the oil-in-water emulsion that contained the methylene blue (MB) dye, along with the complete degradation of MB in an aqueous solution under UV irradiation.

[Display omitted] Janus membranes have attracted much attention for switchable oil/water separation because they have opposite wetting behavior on each side. However, it remains a challenge to fabricate Janus membranes with asymmetric wettability from biomass by simple methods. Herein, we prepared a flexible Janus wood (JW) membrane by cutting the natural wood along the longitudinal direction, followed by a facile top-down approach. The hydrophobic lignin was removed from the wood to prepare a highly porous and superhydrophilic wood (SW) with underwater superoleophobicity. Then, one side of the SW was sprayed with a mixture of 1H,1H,2H,2H-perfluorooctyltrichlorosilane/SiO 2 nanoparticles to form a superhydrophobic surface that hardly affected the wettability of the other side. The obtained JW membrane maintains its selective wettability in harsh environments owing to its durability and stability. Furthermore, it has a switchable, high separation efficiency of >99% for both oil-in-water and water-in-oil emulsions, which can be attributed to the unique wettability and hierarchical micro/nano structure of the JW membrane. Notably, the three-dimensional interconnected micro/nanochannels (pits and nanopores) of the JW membrane are beneficial to the size-sieving effect during emulsion separation. At the same time, the layered channels (tracheids and vessels) enable multiple separations. JW membrane is sustainable, inexpensive, stable, and easy to manufacture, providing more implications for the innovation of biomass-based Janus separation materials in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

Due to ever‐increasing environmental problems caused by oily wastewater, it is necessary to develop methods for separating oil/water mixtures. However, oil‐in‐water and water‐in‐oil emulsions are highly stable due to the action of surfactants, making them enormously difficult to separate. In this study, we report a 3D superhydrophobic/superoleophilic porous material with a microporous structure and strong negative charge via high internal phase emulsion polymerization to overcome these difficulties. The introduction of 10 wt% α‐zirconium phosphate significantly improved the hydrophobicity of the material (water contact angle = 153°) and also endowed the material with a strong negative charge. The material could separate immiscible oil/water mixtures under turbulent condition and high‐ or low‐temperature environments. Driven by gravity, the as‐prepared monolith separated various oil/water mixtures with the separation efficiency exceeding 99.16%. Benefiting from the diametrically‐opposing wettability and interconnected micropore structure, the foam could separate a Span 80‐stabilized water‐in‐oil emulsion. Furthermore, a cationic surfactant‐stabilized oil‐in‐water emulsion was also separated due to strong electrostatic interactions, which destabilized the oil/water interfacial film. Based on these properties, the as‐prepared porous material shows huge potential for complex oily wastewater treatment. [ABSTRACT FROM AUTHOR]

In this work, a novel PCN-222 metal−organic framework based multitasking membrane was developed for separation of emulsified oils as well as photo-Fenton degradation of refractory aromatic pollutants and inactivation of pathogenic bacteria in water. Fe(III)@PCN-222 nanorods were prepared via impregnation method and subjected to amino-modification, and then robustly anchored on polydopamine (PDA) decorated PVDF membrane via catechol-amine reaction. The as-prepared N-Fe(III)@PCN-222/PDA/PVDF composite membrane exhibited underwater superoleophobicity, and showed high separation efficiency (above 99.4 %) as well as relatively favorable permeation flux (874.9–1592.3 Lm−2h−1) in the separation of emulsified oils ranged from nanoscale to microscale from water. Meanwhile, the membrane serving as a recyclable photo-Fenton platform showed an extensive degradation capacity towards aromatic contaminants and high inactivation activity against bacteria under visible light. The grafted Fe(III) is used as an electron acceptor to promote the separation of photo-generated charge carriers, adjusted the band structure to shorten the bandgap value, and can be reduced to Fe(II) by photo-generated electrons as a Fenton-like catalyst. The photo-Fenton mechanism was studied in detail from the aspects of photoelectric properties, band structure and reactive oxygen species. This work could promote the application of PCN subclass MOFs based superwetting membrane as a recyclable platform for complex wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

At present, many oil-water separation membranes are being developed to purify oily wastewater. However, oily wastewater often contains heavy metal, which are often difficult to dispose during separation. Furthermore, most of the oil-water separation membranes cannot be degraded after scrap, producing pollution to environment. Herein, the polyvinyl alcohol/chitosan@carnauba wax (PCGCW) membrane with heavy metal adsorption and biodegradation performance was acquired by electrospinning and spraying process. The acquired PCGCW membrane had excellent mechanical properties after crosslinking glutaraldehyde (GA). Furthermore, the composite membrane had excellent superhydrophobic property (WCA = 154°) with a rolling angle of 2°, due to the introduction of carnauba wax. Exhilaratingly, for emulsions with surfactant, it had a high separation flux with 19,217 L·m−2·h−1·bar−1 and splendid an oil purity over 99.9 %. Besides, the efficiency of oil purity and separation flux remained stable even after 10 separations. In addition, the PCGCW membrane had the ability to adsorb heavy metals with adsorption capacity of 51–106 mg/g for Cu2+, Fe3+, Co2+ ions. Foremost, the superhydrophobic PCGCW membrane was biodegradable, with degrading 29.76 % within 40 days. The prepared composite membrane had the advantages of low cost, high separation flux, great repeatability, adsorbable heavy metals and degradability, which had a vast application prospect. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Converting green tide Enteromorpha prolifera into degradable functional adsorbents. • A biomimetic aerogel was prepared by the multi-sided unidirectional freeze-casting. • The constructed lamellar layers show excellent compressibility and superelasticity. • Superior thermal management enables solar-driven recovery of viscous oil spills. The development of environmental remediation materials from renewable biowaste, especially for the cleanup of viscous oil spills in an eco-friendly manner, marks a substantial advancement in functional materials. This study proposes a biomass aerogel (M−MCEP) transformed from Enteromorpha prolifera (EP) in green tides for solar-driven recovery of high-viscosity oil spills. Inspired by the lamella-bridge architecture of Thalia dealbata stems, a biomimetic structure with multi-domain, long-range aligned lamella-bridge interconnections is constructed by a multi-sided unidirectional freeze-casting technique. Multi-scale interface optimization between rigid photothermal fillers and soft lamellar layers achieves multiple reinforcements, providing aerogel with a perfect balance of elasticity and strength. The multidomain low tortuosity channels and photothermal effects enhance M−MCEP's photothermal conversion (95.2 %) and thermal conductivity (0.3517 W/m·K), reducing oil flow resistance and achieving high oil retention efficiency (>92 %). Under 1 sun irradiation, M−MCEP rapidly heats to 67.3 °C, effectively reducing the viscosity of crude oil in situ, with a crude oil adsorption rate of 1843 mL/m2 within 30 s. Moreover, M−MCEP captures emulsified oil in oil-in-water emulsions through high-speed repeated oscillations, achieving a separation efficiency of 96.42–99.21 %. Renewable resources and unique structural designs provided by nature drive the development of advanced biomimetic aerogels for efficiently remedying catastrophic oil spills. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile, general method is designed to construct gradient colloidal gel coating. • The coating exhibits excellent surface hydration and interface bonding strength. • The coating has a continuous gradient structure to ensure mechanical stability. • The coating shows a reversible flux recovery rate when separating the emulsion. • Gradient colloidal gels have broad application prospects in water treatment. Gradient gel coatings possess superior interfacial bonding strength and surface wettability, providing new ideas for the structure design of separation materials. However, simply and effectively combining colloidal gels that have excellent separation potential with gradient structure design remains a great challenge. Herein, a polymerization-induced microphase separation strategy based on metal ions is developed for constructing colloidal gel coatings with gradient structure on the stainless steel mesh. The colloidal gel is formed by hydrogen-bond complexation and microphase separation of acrylamide and methacrylic acid during polymerization. The metal ions generated by the hydrogen evolution corrosion of stainless steel mesh can not only be used to construct a continuous gradient structure by influencing the microphase separation process but also enhance the mechanical properties and stability of the gel coating. The preparation strategies of traditional gradient materials are limited in the manufacturing and application processes due to their complicated preparation procedures and potential requirement for special equipment assistance. In contrast, this strategy can simply and efficiently prepare colloidal gel coatings with continuous gradient structure by one-pot method under strict monomer ratio. Its unique colloid network demonstrates better wettability and permeability than conventional polymer gel. The prepared gradient colloidal gel coating exhibits excellent separation efficiency (above 99.9 %) and water flux recovery rate (≈98.75 %) in separating surfactant-stabilized emulsion. Therefore, this work provides new insights into the design and preparation of gradient colloidal gels, promoting their development in the field of water treatment. [ABSTRACT FROM AUTHOR]

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. • The pumice has hydrophilic properties and underwater super-oleophobic performance. • Filter membranes were prepared by adsorbing the pumice/PVA suspension onto the PA surface. • The pumice provided excellent underwater super-oleophobic performance to the membrane. • The prepared membrane had excellent emulsion separation efficiency. [ABSTRACT FROM AUTHOR]

Water pollution and solid waste resource reuse demand immediate attention and research. Here, we present a method to create anisotropic cellulose sponges from cotton stalk waste. Using the inherent structure of cotton stalks, we selectively remove lignin and hemicellulose via acid and alkali pretreatment. This process yields cellulose sponges with a natural pore structure. Our findings demonstrate that these sponges retain the original pore configuration of cotton stalks, providing excellent connectivity and compressibility due to their unique anisotropic three-dimensional structure. Moreover, these sponges exhibit exceptional super-hydrophilic and underwater super-oleophobic properties, with underwater oil contact angles exceeding 150° for all tested oils. External pressure can reduce the pore size of the cellulose sponge, facilitating the gravity-driven separation and removal of dyes and emulsions. Remarkably, removal efficiencies for Methylene Blue (MB), Congo Red (CR), water-in-oil (w/o) emulsions, and oil-in-water (o/w) emulsions exceed 99 %, 97 %, 99 %, and 99 %, respectively, highlighting superior removal and recyclability. Further investigation into the mechanisms of dye and emulsion removal employs X-ray photoelectron spectroscopy (XPS) characterization and molecular dynamics (MD) simulation. These insights lay the groundwork for the efficient recycling and resource utilization of waste cotton stalks, offering promising applications in water purification. [Display omitted] ● Cotton stalk was used to make anisotropic cellulose sponge materials. ● The sponges without any additives. ● The sponges showed high removal efficiency of dyes (over 97 %). ● The sponges also had excellent removal effects on o/w and w/o emulsions (over 99 %). ● The preparation and application of sponge demonstrates "curb-waste-with-waste". [ABSTRACT FROM AUTHOR]

[Display omitted] • PDMS shell graft on PAN nanofiber core for heterogeneous nanofibrous membranes. • The aggregation-release demulsification process for stable emulsion separation. • Both purified water and aggregated oil phase could be recovered from the permeates. Efficient oil/water recovery from emulsions is a challenging task for membrane separation in terms of perm-selectivity and long-term stability. Oil fouling on membrane surface and intrapore disables the efficient recovery of water and oil, limited by size exclusion. Herein, this work proposes an aggregation-release demulsification mechanism to address the fouling issue and achieve efficient oil and water recovery, respectively. Specifically, an ultra-thin sub-10 nm polydimethylsiloxane (PDMS) shell layer was constructed on a hydrophilic polyacrylonitrile (PAN) nanofiber core surface through the hydrolysis and condensation between vinyltriethoxysilane (VTES) and dimethoxydimethylsilane (DMS). The aggregation-release demulsification process on the lipophilic and slippery PDMS surface could be proposed as, oil droplet adsorption, spread out, aggregation and slippery, which vacates the membrane pore space and makes way for water flow. Thus, both purified water and aggregated oil phase could be easily recovered from the permeates. The prepared membrane enabled continuous operation without cleaning. The membrane shows high water permeance (2800 L m-2h−1 bar−1), high emulsion treatment capacity (8000 mL), and high oil (∼85 %) and water (nearly 100 %) recovery. The strategy reported in the current study might offer an opportunity for advancing practical applications of membrane separation for valuable oil products from emulsions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The preparation of this membrane is simple and free of organic polymers. • The membrane can achieve almost 100% separation rates for oil–water emulsions. • The membrane exhibits recyclable separation performance and great flexibility. • The membrane in this work is environmentally friendly and fully degradable. Flexible membranes have attracted extensive attention in water treatment due to their outstanding plasticity, portability, and toughness. However, conventional flexible membranes are usually made from non-degradable polymers or hazardous reagents, posing threats to the environment. In this work, a flexible silica nanofiber-regenerated cellulose composite membrane was fabricated by "no polymer solvents electrospinning" with cellulose regeneration. The membrane was fully degradable and eco-friendly, and it exhibited low oil adhesion force and recyclable oil emulsion separation performance. It achieved removal rates of almost 100 % and up to 0.1 % residual oil rate for six different types of oil emulsions with the addition of surfactant, which represents the optimal level reported in the literature to date. The presence of these extremely water-attracting functional groups on the surface of the membrane allows them to bond with water molecules, creating a stable water layer held together by hydrogen bonds. This layer can reject oil compounds during the separation process due to the inherent immiscibility between water and oil. Importantly, this membrane has excellent degradability. The regenerated cellulose layer on its surface can undergo complete microbial degradation (activated sludge) within 7 days, while the remaining substrate can be degraded continuously in concentrated hydrochloric acid, thereby facilitating complete environmentally benign disposal and providing a new strategy for developing green flexible membranes, which holds promise for addressing water scarcity and water pollution issues. [ABSTRACT FROM AUTHOR]

Despite the emergence of hydrogels as ideal candidates for preparing the superhydrophilic materials for emulsion separation, their structural stability and swelling still hinder their long-term use, mainly due to structure defects after swelling. Herein, differing from the common modification, the eco-friendly poly 2-hydroxyethyl methacrylate (pHEMA) hydrogel foam was designed and synthesized via a one-step strategy by using the high internal phase emulsion (HIPE) template method, which endowed it with a highly interpenetrated porous structure. Unlike the normal swellable hydrogels such as poly(N-isoproplyacrylamide) (PNIPAM) hydrogel, or modified hydrogel coatings, the pHEMA hydrogel foam displayed stable structure and underwater superoleophobicity after 20 d of immersion in water. The pHEMA hydrogel foam could separate different kinds of highly surfactant-stabilized oil-in-water (O/W) emulsions with a high separation efficiency of 99.3% for liquid paraffin emulsion obtained solely under gravity-driven. Additionally, it exhibited excellent antifouling performance and long-term acid/alkali tolerance over 100 h without decrease in emulsion separation efficiency (98.0%, oil/water ratio of 99:1) and permeation flux (over 2000 L·m−2·h−1) attributed to its stable bulky structure. Moreover, the pHEMA hydrogel foam demonstrated high cell viability of 96.87% and 95.96% after culturing the 3T3 clone A31 cells in the pHEMA hydrogel foam for 24 h and 48 h, respectively, indicating good biocompatibility. Hence, our work provides a new design to develop an eco-friendly bulk hydrogel foam that achieves stable structure and performance for emulsion separation. [Display omitted] • Eco-friendly pHEMA hydrogel foam was designed and synthesized via HIPE method. • It displayed stable volume, structure and underwater superoleophobicity. • It exhibited stable and effective performance for emulsion separation. • It possessed excellent antifouling, acid/alkali tolerance and biocompatibility. • The hydration layer in hydrogel foam endows effective oil repellency. [ABSTRACT FROM AUTHOR]

The design and fabrication of advanced membrane materials for versatile oil/water separation are major challenges. In this work, a superwetting stainless steel mesh (SSM) modified with in situ-grown TiO2 was successfully prepared via one-pot hydrothermal synthesis at 180 °C for 24 h. The modified SSM was characterized by means of scanning electron microscopy, energy spectroscopy, and X-ray photoelectron spectroscopy analysis. The resultant SSM membrane was superhydrophilic/superoleophilic in air, superoleophobic underwater, with an oil contact angle (OCA) underwater of over 150°, and superhydrophobic under oil, with a water contact angle (WCA) as high as 158°. Facile separation of immiscible light oil/water and heavy oil/water was carried out using the prewetting method with water and oil, respectively. For both “oil-blocking” and “water-blocking” membranes, the separation efficiency was greater than 98%. Also, these SSMs wrapped in TiO2 nanoparticles broke emulsions well, separating oil-in-water and oil-in-water emulsions with an efficiency greater than 99.0%. The as-prepared superwetting materials provided a satisfactory solution for the complicated or versatile oil/water separation.

In this study, using chitosan (CS) and carboxymethyl cellulose (CMC) as backbone and introducing citric acid (CA)to enhance the electrostatic interaction of the system, citric acid/chitosan/carboxymethyl cellulose (CA/CS/CMC) aerogel is obtained by simple freeze-drying. CA/CS/CMC composite aerogel exhibits light weight, low density, high porosity, outstanding hydrophilic and water retention properties, and satisfactory underwater oleophobicity. The water adsorption capacity of the obtained aerogels can reach 43.87–80.28 g/g, which are far more than that of carboxymethyl cellulose and chitosan aerogels (14.27–20.08 g/g). In addition, with strong hydrophilicity, underwater oleophobicity and water retention endowed by the rough internal microstructure and the rich hydroxyl, amino, and carboxyl groups, the fabricated aerogel can also be used as a filter to achieve effective separation of oil-in-water emulsions and oil/water mixtures. The separation efficiency of aerogel for oil/water mixtures are higher than 90.7%. Because the developed preparation method is green, simple and mild and the raw materials are readily available and environmentally friendly, the obtained CA/CS/CMC aerogel with strong water absorption capacity and good separation efficiency displays a promising application in water-oil separation.

Oily wastewater discharge causes not only the pollution of environment but also the waste of resources. Existing technologies for wastewater remediation, such as membrane and particle methods, are variable and effective, but are difficult for achieving continuous and rapid oil–water separation. Here, with the synergy of turbo stirring, a strategy for emulsion separation is demonstrated based on the bio‐inspired cone array barrel. Under the centrifugal force, oil droplets in emulsion are thrown onto the cones arrayed on inner wall due to the Coriolis effect, captured by microstructures on cone surface and then penetrate out through the superhydrophobic pores, while only the remediated water remains. The separation technique maintains a high efficiency of above 99.5% for over 30 times of use, as well as for emulsions with variable ingredients. This structure‐dynamics synergistic separation strategy evolves the future technologies on water purification in industrial and daily processes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Oil-water separation materials with excellent chemical stability are urgently needed in the treatment of oily wastewater. In this work, in order to effectively separate various oily-water emulsions in complex environments such as acid, alkali and salt, with stainless steel mesh (SSM) as the base, copper sulfide (Cu2S) was modified on the surface of stainless steel mesh by electrochemical deposition and solution reaction to successfully prepare Cu2S@SSM composite membrane. The prepared Cu2S@SSM composite membrane exhibited excellent superhydrophilic/underwater superhydrophobic properties. A series of oil-in-water emulsion, including surfactant-free and surfactant-stabilized of-in-water emulsions, separation experiments were conducted. The permeation fluxes as high as 932 and 361 L/(m² ⋅ h) and the separation efficiency as high as 99.78% and 99.15% were obtained, respectively. Thanks to the photo-Fenton catalytic performance of Cu2S, the degradation rate of Cu2S @SSM composite film to methylene blue and rhodamine B is up to 99% under visible tight irradiation. More importantly, the Cu2S@SSM composite membrane shows excellent chemical stability in strong acid, strong alkali and high salt environments. [ABSTRACT FROM AUTHOR]

The pollution arising from emulsified oil/water mixtures is an issue of great concern owing to its fatal impact on the ecosystems and human health, which has stimulated one to develop advanced separation materials. Electrospun nanofibrous materials featured with controllable wettability, diverse pore structures, and excellent pore connectivity have received tremendous attention. Here we mainly focus on the systematic design and construction of nanofibrous materials by electrospinning for oil/water emulsion separation. Firstly, a comprehensive understanding of emulsion separation is provided, and then we discuss the considerations for nanofibrous materials to realize emulsion separation. Then, the materials will be categorized into three types, involving membranes with small pore size, membranes with hierarchical fibers, and aerogel with tortuous microchannels. In each section, we introduce the representative work, preparation strategies, and the relationship between fibrous structure, material wettability, and separation performance. Finally, the promising perspectives and challenges in the field are summarized. [ABSTRACT FROM AUTHOR]

In human life and production, excessive oily wastewaters containing detergents are produced and discharged, causing severe environmental pollution and water resource problems. A metal-organic framework (MOF)-based membrane is an economical and environmentally friendly tool for emulsion separation but is limited by a complex preparation process and poor flexibility. Herein, we developed a simple method to synthesize a MOF-based mixed-matrix membrane (MMM) by spray and fabricated the membrane on poly(vinylidene fluoride) (PVDF) fibers via postdeposition and in situ growth manners. The prepared ZIF-8/PVA MMMs have uniform distribution of ZIF-8 particles and poly(vinyl alcohol) (PVA) on the PVDF fibers. PVA improved the adhesion between the ZIF-8 particles and between the MOF layer and PVDF fiber, endowing the separation membrane with high flexibility and bendability. The prepared ZIF-8/PVA membrane exhibited hydrophilicity and underwater superoleophobicity, which showed high separation efficiency and considerable water flux for emulsions, emulsion containing dye, and surfactant-stabilized emulsion. In addition, the fabricated ZIF-8/PVA/PVDF fibers exhibited good antifouling property and flexibility and can maintain stable separation efficiency after working several times and even under bending, demonstrating the stability and potentiality of the ZIF-8/PVA/PVDF fibers in practical applications. This work paves a new avenue for the synthesis and application of MOF-based MMMs.

Maintaining high separation performance during continuous emulsion separation remains a challenge. Herein, based on biomimetic coupling ideas, hole array interlaced wetting surfaces (HAIWSs) and mastoid array interlaced wetting surfaces (MAIWSs) were prepared by laser processing, electroless silver deposition, thiol modification, and spraying for on-demand emulsion separation. When the separation is going on, randomly moving emulsion droplets are prone to being captured by holes or mastoids due to interlaced wettability. Under this unique interface behavior, the occurrence of filter cake and pore clogging is reduced, thus achieving both high efficiency (∼99.5 and ∼99.3 %). Meanwhile, the high flux can also be maintained (∼3212 and ∼3458 L m -2 h -1 ). Significantly better than surfaces without pores or mastoid structures. Further, the as-prepared surfaces also exhibit excellent recyclability. After 50 separation cycles, optimized HAIWS and MAIWS still maintained high efficiency (∼96.2 and ∼95.8 %) and high flux (∼3042 and ∼3164 L m -2 h -1 ), exceeding other surfaces without hole or mastoid structure. Notably, complex physical/chemical cleaning processes are avoided. Besides, even in harsh conditions, HAIWS and MAIWS still maintain excellent stability. The above strategy provides a novel mechanism for effective on-demand emulsion separation and is expected to encourage the creation of new-class separation devices for oily wastewater treatment in industry., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

High-performance separation materials for oil-water emulsions are crucial to environmental protection and resource recovery; however, most existing fibrous separation materials are subject to large pore size and low porosity, resulting in limited separation performance. Herein, we create high-performance membranes consisting of spherical-beaded nanofibers and nanoarchitectured networks (nano-nets) using electrostatic spinning/netting technology, for water-in-oil emulsion separation. By manipulating the nonequilibrium stretching of jets, spherical-beaded nanofibers capable of generating a robust microelectric field are fabricated as scaffolds, on which charged droplets are induced to eject and phase separate to self-assemble nano-nets with small pores. Benefiting from 3D undulating networks with cavities originating from 2D nano-nets supported by 1D spherical-beaded nanofibers, the membranes exhibit under-oil superhydrophobicity (>152°), a striking separation performance with an efficiency of >99.2% and a flux of 5775 L m -2 h -1 , together with wide pressure applicability, antifouling, and reusability. This work may open up new horizons in developing fibrous materials for separation and purification.

Considering the potential threats posed by oily wastewater to the ecosystem, it is urgently in demand to develop efficient, eco-friendly, and intelligent oil/water separation materials to enhance the safety of the water environment. Herein, an intelligent hydrogel-coated wood (PPT/PPy@DW) membrane with self-healing, self-cleaning, and oil pollution detection performances is fabricated for the controllable separation of oil-in-water (O/W) emulsions and water-in-oil (W/O) emulsions. The PPT/PPy@DW is prepared by loading polypyrrole (PPy) particles on the delignified wood (DW) membranes, further modifying the hydrogel layer as an oil-repellent barrier. The layered porous structure and selective wettability endow PPT/PPy@DW with great separation performance for various O/W emulsions (≥98.69% for separation efficiency and ≈1000 L m -2  h -1  bar -1 for permeance). Notably, the oil pollution degree of PPT/PPy@DW can be monitored in real-time based on the changed voltage generated during O/W emulsion separation, and the oil-polluted PPT/PPy@DW can be self-cleaned by soaking in water to recover its separation performance. The high affinity of PPT/PPy@DW for water makes it effective in trapping water from the mixed surfactant-stabilized W/O emulsions. The prepared eco-friendly and low-cost multifunctional hydrogel wood membrane shows promising potential in on-demand oil/water separation and provides new ideas for the functional improvement of new biomass oil/water separation membrane materials., (© 2024 Wiley‐VCH GmbH.)

The fouling phenomenon of membranes has hindered the rapid development of separation technology in wastewater treatment. The integration of materials into membranes with both excellent separation performance and self-cleaning properties still pose challenges. Here, a self-assembled composite membrane with solar-driven self-cleaning performance is reported for the treatment of complex oil-water emulsions. The mechanical robustness of the composite membrane is enhanced by the electrostatic attraction between chitosan and metal-organic frameworks (MOF) CuCo-HHTP as well as the crosslinking effect of glutaraldehyde. Molecular dynamics (MD) simulations also revealed the hydrogen bonding interaction between chitosan and CuCo-HHTP. The composite membrane of CuCo-HHTP-5@CS/MPVDF exhibits a high flux ranging from 700.6 to 2350.6 L∙m -2 ∙h -1 ∙bar -1 and excellent separation efficiency (>99.0%) for various oil-water emulsions, including crude oil, kerosene, and other light oils. The addition of CuCo-HHTP shows remarkable photothermal effects, thus demonstrating excellent solar-driven self-cleaning capability and antibacterial performance (with an efficiency of ≈100%). Furthermore, CuCo-HHTP-5@CS/MPVDF can activate peroxomonosulfate (PMS) under sunlight, quickly removing oil-fouling and dyes. Density functional theory (DFT) calculations indicate that the bimetallic sites of Cu and Co in CuCo-HHTP effectively promoted the activation of PMS. This study provides distinctive insights into the multifaceted applications of MOFs-derived photothermal anti-fouling composite membranes., (© 2024 Wiley‐VCH GmbH.)

Oil-water separation based on superwettable materials offers a promising way for the treatment of oil-water mixtures and emulsions. Nevertheless, such separation techniques often require complex devices and external energy input. Therefore, it remains a great challenge to separate oil-water mixtures and emulsions through an energy-efficient, economical, and sustainable way. Here, a novel approach demonstrating the successful separation of oil-water emulsions using antigravity-driven autonomous superwettable pumps is presented. By transitioning from traditional gravity-driven to antigravity-driven separation, the study showcases the unprecedented success in purifying oil/water from emulsions by capillary/siphon-driven superwettable autonomous pumps. These pumps, composed of self-organized interconnected channels formed by the packing of superhydrophobic and superhydrophilic sand particles, exhibit outstanding separation flux, efficiency, and recyclability. The findings of this study not only open up a new avenue for oil-water emulsion separation but also hold promise for profound impacts in the field., (© 2024 Wiley‐VCH GmbH.)

Abstract Oily wastewater discharge causes not only the pollution of environment but also the waste of resources. Existing technologies for wastewater remediation, such as membrane and particle methods, are variable and effective, but are difficult for achieving continuous and rapid oil–water separation. Here, with the synergy of turbo stirring, a strategy for emulsion separation is demonstrated based on the bio‐inspired cone array barrel. Under the centrifugal force, oil droplets in emulsion are thrown onto the cones arrayed on inner wall due to the Coriolis effect, captured by microstructures on cone surface and then penetrate out through the superhydrophobic pores, while only the remediated water remains. The separation technique maintains a high efficiency of above 99.5% for over 30 times of use, as well as for emulsions with variable ingredients. This structure‐dynamics synergistic separation strategy evolves the future technologies on water purification in industrial and daily processes.

Here, we report a metal–organic framework (MOF) [Hf6O4(OH)4(TFNDC)6]·6H2O·2DMF [SHMOF, where TFNDC = 1-(2,2,2-trifluoroacetamido)-naphthalene-3,7-dicarboxylate], which possesses excellent chemical and thermal stability along with remarkable hydrophobic characteristics. The hydrophobic SHMOF was used for in situ coating on the polypropylene (PP) fabric to make a superhydrophobic SHMOF–PP fabric composite. The immobilization of nanocrystalline particles of SHMOF creates a nanoscale hierarchy that enhances the hydrophobicity of the material. The superhydrophobic SHMOF–PP composite showed a water contact angle of 160°. The successful integration of the MOF compound with PP fabric was confirmed using field-emission scanning electron microscopy, X-ray powder diffraction spectroscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray analysis experiments. Superhydrophobic SHMOF–PP composite displayed a high separation efficiency (93–99%) for separating light, heavy, and crude oils from oil–water mixtures. The flux for oil–water separation was found to be 13–18k L m–2 h–1. Importantly, the SHMOF–PP composite can be used repetitively up to a minimum of 20 times for oil–water separation. The recyclability was also maintained in high acidic and alkaline media. Moreover, superhydrophobic SHMOF–PP composite showed excellent oil absorption capacity (29–39 g/g) for heavy and light oils at ambient temperature. A gravity-driven active-filtration process and separation against the gravity process were also performed to examine the flexibility of the composite for separation. We demonstrate that the SHMOF–PP composite has the merit of very high separation efficiency, absorption capacity, good recyclability, and exceptional robustness, showing high potential for versatile oil–water separation. Additionally, the material displayed noticeable self-cleaning and antifouling properties. The SHMOF–PP composite also exhibited good efficiency (95–99%) and flux density (1845–1899 L m–2 h–1) for the separation of water-in-oil emulsions. [ABSTRACT FROM AUTHOR]

Wastewater containing oil and surfactant pollution causes health, environment, and resource issues. Surfactant‐stabilized emulsion separation is conventionally achieved by modified sponges, membranes and micro‐nanoparticles, still, with relevant limitations in low durability, high energy consumption, and discontinuity. Inspired by nasal cavity, a superhydrophobic/superoleophilic nanowires decorated cone array tube with penetrated pores is demonstrated for oil recovery in micron‐sized oil‐in‐water emulsions. The experimental results reveal that the separation efficiency can reach 99.84% and the oil recovery efficiency can achieve 92% at the same time. Oil droplets are captured by cones under the synergy of superwettability and gradient structure, and then transport driven by the force of Laplace pressure. The whole process of oil recovery in wastewater is continuous, durable, and versatile for different oil/surfactant contents. This work will effectively control wastewater pollution and facilitate oil resource recovery, and opens the possibility of phase separation in various applications, such as chip microfluidics, beverage refining, and drug screening. [ABSTRACT FROM AUTHOR]

Due to the trade‐off between purity and flux, the development of high‐purity, high‐flux oil–water separation materials is still an arduous challenge. Herein, to achieve emulsion separation with high purity and high permeability, fluorinated graphene/poly(vinyl alcohol) aerogel (FGPA) with strong honeycomb was obtained via a facile freeze‐drying method, and the separation mechanism was investigated via computational fluid dynamics (CFDs) simulation. The as‐prepared FGPA exhibited superhydrophobicity‐superoleophobicity and cyclic compression stability. Under the complex pore and superhydrophobicity, FGPA could separate water‐in‐oil emulsions with droplet sizes several times smaller than their own aperture only under gravity with ultrahigh flux (3255 L m−2 h−1) and ultrahigh purity (99.9%). Also, the separation process as visualized using simulations revealed that the vortex accelerates the demulsification behavior and promotes the gathering of water droplets rebounding on the superhydrophobic surface, so that the water droplets are intercepted. Therefore, FGPA has broad practical application potential in high‐flux and high‐purity oil–water emulsion separation. [ABSTRACT FROM AUTHOR]

The development of microfiltration (MF) membranes with a high separation flux and antifouling ability is an ultimate goal for the purification of emulsified oily wastewater by MF techniques. Herein, a dual‐functional MIL‐100(Fe)@graphene oxide (MIL‐100(Fe)@GO) membrane is fabricated by in situ growth of MIL‐100(Fe) with a graphene oxide (GO) nanosheet. The porous MIL‐100(Fe)@GO composite endows the MF membrane with superhydrophilicity and demulsification functions. The MIL‐100(Fe)@GO membrane achieves an outstanding water permeation flux of 12 457 L m−2 h−1 bar−1, as encouraged by the versatility of MIL‐100(Fe) in enabling superhydrophilicity of the MIL‐100(Fe)@GO membrane and providing rich water permeation channels. An impressive emulsion separation efficiency of >99% and maximum emulsion separation flux of 5529 L m−2 h−1 bar−1 are thus delivered by the MIL‐100(Fe)@GO membrane. Moreover, a 131% recovery ratio of emulsion separation flux (7135 L m−2 h−1 bar−1) is attained with this system after regeneration by ethanol. In virtue of the demulsification of MIL‐100(Fe), the rational design of the MIL‐100(Fe) hybrid membrane exhibits a self‐cleaning effect on the emulsion separation. The demonstrated high performance of the membrane system opens up new avenues for the development of membranes with antifouling abilities and ultrahigh flux for emulsion separation. [ABSTRACT FROM AUTHOR]

Abstract Developing high-performance separation membrane with good durability is a highly desired while challenging issue. Herein, we reported the successful fabrication of chemically and mechanically durable superhydrophobic membrane that was prepared by embedding UiO-66 as size-sieving sites within the supramolecular fiber structure of collagen fiber membrane (CFM), followed by the polydimethylsiloxane (PDMS) coating. The as-prepared CFM/UiO-66(12)/PDMS membrane featured capillary effect-enhanced separation flux and homogeneous porous channels guaranteed high separation efficiency. When utilized as double-layer separation membranes, this new type of composite membranes separated various surfactant stabilized water-in-oil microemulsions and nanoemulsions, with the separation efficiency high up to 99.993 % and the flux as high as 973.3 L m− 2 h− 1. Compared with commercial polytetrafluoro ethylene (PTFE) membrane, the advantage of the double-layer CFM/UiO-66(12)/PDMS membranes in separation flux was evident, which exhibited one order of magnitude higher than that of commercial PTFE membrane. The CFM/UiO-66(12)/PDMS membrane was acid-alkali tolerant, UV-aging resistant and reusable for emulsion separation. Notably, the CFM/UiO-66(12)/PDMS membrane was mechanically durable against strong mechanical abrasion, which was still capable of separating diverse water-in-oil emulsions after the abrasion with sandpaper and assembled as double-layer separation membranes. We anticipate that the combination of CFM and metal organic frameworks (MOFs) is an effective strategy for fabricating high-performance separation membrane with high mechanical and chemical durability. Graphical Abstract