Efficient Separation Of Oil Research Articles

Design and Performance Evaluation of CuBTC MOF-Functionalized Copper Mesh-Based Oil Collector for Efficient Oil-Spill Remediation

Oil spills pose severe ecological risks and resource losses, with only 2%–6% of the spilled oil typically recovered despite advancements in cleanup techniques. To address this challenge, an oil-collecting vessel featuring a copper mesh functionalized with perfluorooctyl triethoxysilane-modified copper benzene tricarboxylate metal-organic frameworks (MOFs) was developed. This mesh exhibited superhydrophobic properties (water contact angle ~150˚, sliding angle <10˚) while maintaining a ~0˚ contact angle for oil. This selective wettability enabled the efficient separation of oil from oil–water mixtures, achieving up to 100% separation efficiency. The mesh was also effective in separating non-polar liquids such as hexane and chloroform from multi-phase mixtures. Utilizing a horizontal filtration approach, the vessel was floated on the mixture surface, taking advantage of low static pressures to accommodate larger-pore meshes. The effect of mesh pore size on oil collection was studied, and meshes with 279-µm pores achieved the highest oil influx rates (up to 162,469L/h-m² for hexane), while maintaining water resistance (hydrostatic pressure ~800Pa). Reusability tests demonstrated the mesh’s robustness, with efficiencies near 100% after 10 cycles. Water contact angle measurements and FTIR analysis confirmed stability during continuous use, even after exposure to harsh alkaline environments and solvents. Mechanical durability tests further highlighted thermal stability up to 250˚C and consistent separation performance after significant abrasion. This study presents a promising solution to oil spill remediation, advancing recovery efficiency with a durable and versatile approach.

The role of miscible PAG lubricants in ammonia refrigeration systems reduction and compactness

Today’s society is going through an expanding use of natural refrigerants, earlier present only in big industrial facilities. This has made necessary the charge reduction and compactness improvement of the equipment, to fit the safety measures and standards requirements. The refrigerant charge and the complexity of an ammonia refrigeration system are mainly because of flooded evaporators use and the need for an efficient oil separation system, since conventional lubricants and ammonia are immiscible. The use of ammonia miscible lubricants can address the oil separation problem. A Poly-Alkylene-Glycol (PAG) can be designed and formulated to be miscible with ammonia, and the plant operated like a conventional halocarbon refrigerant one. The circulating lubricant will be recovered through the compressor suction port of the compressor. This will help in the operation of Direct Expansion (DX) evaporators, reducing to a testimonial size the oil separation circuit. This article is a translation of the article by Muñoz-Alonso M, Dixon L, Seeton CJ, Karnaz J. The role of miscible PAG lubricants in ammonia refrigeration systems reduction and compactness. In: Proceedings of the 9th IIR Conference on the Ammonia and CO2 Refrigeration Technologies. Ohrid: IIF/IIR, 2021. DOI: 10.18462/iir.nh3-co2.2021.0018 Published with the permission of the copyright holder.

Multifunctional aluminum 12-hydroxystearate/lignin polyurethane foam for selective gelation and efficient separation of oil and organic solvents

During frequent transportation, the marine environment is continuously exposed to significant threats from crude oil and organic solvent leakage. Non-covalent self-assembly of organogelator on the adsorbent matrix to fix non-polar solvents is an efficient and sustainable remediation method. This contribution proposes an organogelator-adsorbent composite by blending aluminum 12-hydroxystearate (Al HSA) and expanded graphite (EG) during lignin-based polyurethane foaming. Al HSA molecule synergizes with EG to modulate the shape (hexagonal), oil retention, mechanical property, and hydrophobicity (water contact angle = 151.3°) of the lignin-based polyurethane foam (LPUF) skeleton. Al HSA-LPUF (OTS-LPUF/EAH) superhydrophobic foam exhibits sorption capacity up to 13.2–53.0 g g−1 in various oils and organic solvents. From the microscopic morphology, the Al HSA on the skeleton self-assembles into spherical nanoclusters driven by hydrogen bonding, realizing the capturing of oils and organic solvents. Even after 20 cycles, the foam still has a high oil/water separation capacity and mechanical performance. OTS-LPUF/EAH also shows improved flame retardancy and a 61 % reduction in total smoke release (TSR) compared to pristine LPUF.

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

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

Hydrophobic silicone modified membranes for efficient oil/water separation: Synthesis, fabrication and application

Oil leakage and discharge of organic wastewater have not only threatened the ecosystem, but also greatly aggravated water scarcity. Efficient separation of oil–water mixture has become a global challenge. To solve this issue, various hydrophobic membranes with special wettability have been developed in past decades. Among them, the hydrophobic silicone-modified membranes have attracted much attention due to their low cost, easy processing and large-scale production. Herein, recent progresses of hydrophobic silicone-modified membranes for oil–water separation are reviewed. Basic mechanisms and principles for efficient oil–water separation are presented as a starting point for the discussion. Then, according to the modified silicone polymers or molecules, we give a detail description of their synthesis and briefly introduce the main reactions with the substrate, the typical grafting strategy and fabricating methods. Subsequently, the performance and oil–water application of various hydrophobic membranes modified silicone are introduced. Finally, some problems and challenges faced by silicone modification are summarized and present, and their future development is also prospected.

Underoil superhydrophilic nanofiber-based composite aerogels for efficient separation of water/oil mixtures and water-in-oil emulsions

Oily wastewater has caused serious environmental problems. To achieve efficient separation of oil/water mixtures and surfactant-stabilized water-in-oil emulsions, electrospinning, directional freeze-casting and thermal treatment techniques were combined to fabricate anisotropic and aligned nanofiber-based composite aerogels with underwater superoleophobicity and underoil superhydrophilicity. No toxic crosslinking agents or organic solvents were used during the whole fabrication process. The composite aerogels without any surface modification possessed the ability to selectively absorb water from oil/water mixtures to realize effective separation oil and water. Furthermore, the composite aerogels could separate surfactant-stabilized water-in-oil emulsions by gravity-driven filtration. When used for gravity-driven separation of Span80 stabilized water-in-petroleum ether emulsion, the flux and corresponding separation efficiency reached 2423 L·m−2·h−1 and 99.8 %, respectively. The used composite aerogel could be readily recycled by rinsing and freeze-drying without using any organic solvent, because it displayed underoil superhydrophilicity and excellent anti-oil property. Differing from the separation materials that have been previously documented, the nanofiber-based composite aerogels could act as both absorption materials and gravity-driven filtration materials. In summary, the composite aerogels developed in this study show great potential for efficient separation of oil and water.

Self-cleaning SiO2–TiO2 ceramic membrane for enhanced oil–water separation

An efficient and practical method is proposed for the separation of oil–water mixtures and emulsions in sustainable water ecosystems, facilitating energy recovery. The construction of flexible ceramic fiber membranes with high throughput and self-cleaning capabilities has proven effective but challenging. This study reports a novel approach combining the sol–gel and electrospinning techniques to synthesize flexible silicon dioxide (SiO2)–titanium dioxide (TiO2) nanofiber membranes (STNFMs). These membranes possess nanoscale rough structures, granting them superhydrophilicity and underwater superoleophobicity (155°). Exploiting the photocatalytic properties of titanium dioxide, STNFMs-4 not only demonstrates excellent separation performance but also exhibits remarkable self-cleaning abilities. After 2 h of ultraviolet light irradiation, the membrane flux returns to its original level. STNFMs provide a promising solution for highly efficient separation of oil–water mixtures and emulsions, with the potential to play a significant role in water treatment and resource recovery.

Synthesis of cost-effective Si-CQD for effective oil separation from core rock

Nanomaterials (NMs) based on carbon are suitable candidates for separating oil from core rock. Nowadays, the application of carbon-based NMs to enhanced oil recovery (EOR) is far less. The production of NMs based on carbon (water-wet) is of great importance due to the high recovery they create in reservoirs. The purpose of this study was to change the wettability of oil-wet (OW) carbonate rock (CR) towards water-wet (WW) conditions using cheap synthetic materials. In this regard, the effect of three quantum carbon dots (CQDs) on saltwaters has been used. The CQDs were synthesized by hydrothermal procedure and tetraethyl orthosilicate (TEOS) was used as the initial source of carbon. In this regard, Si-CQDs indicated great colloidal sustainability in saltwaters solutions. Therefore, to determine the morphological characteristics and structure of the synthesized NMs, Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) were done. The stability of NMs was investigated using the zeta potential (ZP). The new compound showed acceptable results at a very low concentration of 100 ppm. The findings indicated that the nanofluid (100 ppm Si-CQDs + Seawater (SE)) reduced the interfacial tension value from 23.34 mN/m to 7 mN/m. Also, the results showed the solution of SE + 100 ppm Si-CQDs improved the oil recovery by 24 % and 23 %. Generally, this paper opens the door for the development of carbon-based NMs with the ability to absorb sediments in the porous media of the reservoir for the efficient separation of oil from core rock. Generally, our analysis supports the use of Si-CQDs as an efficient and economical additive for further oil recovery in carbonate reservoirs.

Superhydrophobic PODS-modified nickel foam with reversible wettability for oil-water separation

In this work, superhydrophobic and superoleophilic nickel foam was fabricated to effectively purify oil-water mixtures. Octadecyltrichlorosilane (OTS) was utilized to form polymerized octadecylsiloxane (PODS) coatings on the nickel foam through hydrolysis and subsequent polycondensation reactions. The surface composition and morphology of the nickel foam were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The initially smooth surface of the nickel foam became rough upon being coated with the PODS. The incorporation of long alkyl chains from the PODS coating, along with the introduced roughness, synergistically provided the nickel foam with superhydrophobic and superoleophilic properties. The PODS-modified nickel foam demonstrated a water contact angle (WCA) of 151.3° and oil contact angle (OCA) of 0°, exhibiting excellent wettability selectivity towards water and oil. Additionally, it showcased a remarkable permeation flux of 7468.4 ± 236.3 L·m−2·h−1 when tested with a water-n-hexane emulsion. This superior performance enabled efficient separation of oil and water. Notably, even after 20 cycles, the PODS-modified nickel foam maintained a separation efficiency of over 98.4 %. Furthermore, the wettability of the PODS-modified nickel foam could be easily switched from superhydrophobicity to superhydrophilicity through a straightforward prewetting treatment using ethanol. In this process, ethanol served as a mediator between the hydrophobic surface and water. Once the prewetted foam was thoroughly dried, the hydrophilic channels were eliminated, thus restoring the superhydrophobicity of the nickel foam. This reversible transition of wettability holds great potential for the development of smart filters capable of effectively addressing diverse challenges in oily wastewater treatment.

Preparation of inorganic–organic composite coagulant and its mechanism in destroying emulsified oil in oilfield sewage

The complexity of oily sewage from oilfields has risen with the advancement of polymer flooding technology, thereby increasing the treatment challenge. In this study, a composite coagulant, PVPAM-PPFS, was proposed, inspired by octopus tentacles, with PVP as the backbone. FTIR, 1H NMR and Rg radius of gyration were used to characterize the functional groups and conformation of PVPAM-PPFS in aqueous environments. The composite coagulant exhibits facile dispersion in water. Upon hydrolysis of PVPAM-PPFS, numerous molecular chains resembling octopus tentacles are formed and confirmed through Atomic Force Microscopy (AFM). When applied to oily sewage in oilfields, PVPAM-PPFS demonstrates enhanced interaction with emulsified oil layers, capturing colloidal particles in water and thereby facilitating efficient separation of oil, water, and flocs. Lastly, the mechanism of PVPAM-PPFS was analyzed through a combination of coagulation experiments and detection of floc morphology. PVPAM-PPFS will better interact with colloidal particles in water through increased charge neutralization, bridging adsorption, and sweeping capabilities. Significantly, an enhanced crude oil recovery rate is observed from the recovered oil droplets following the disruption of the emulsion layer.

Hierarchical Ni-Mn LDHs@CuC2O4 Nanosheet Arrays-Modified Copper Mesh: A Dual-Functional Material for Enhancing Oil/Water Separation and Supercapacitors.

The pursuit of superhydrophilic materials with hierarchical structures has garnered significant attention across diverse application domains. In this study, we have successfully crafted Ni-Mn LDHs@CuC2O4 nanosheet arrays on a copper mesh (CM) through a synergistic process involving chemical oxidation and hydrothermal deposition. Initially, CuC2O4 nanosheets were synthesized on the copper mesh, closely followed by the growth of Ni-Mn LDHs nanosheets, culminating in the establishment of a multi-tiered surface architecture with exceptional superhydrophilicity and remarkable underwater superoleophobicity. The resultant Ni-Mn LDHs@CuC2O4 CM membrane showcased an unparalleled amalgamation of traits, including superhydrophilicity, underwater superoleophobicity, and the ability to harness photocatalytic forces for self-cleaning actions, making it an advanced oil-water separation membrane. The membrane's performance was impressive, manifesting in a remarkable water flux range (70 kL·m-2·h-1) and an efficient oil separation capability for both oil/water mixture and surfactant-stabilized emulsions (below 60 ppm). Moreover, the innate superhydrophilic characteristics of the membrane rendered it a prime candidate for deployment as a supercapacitor cathode material. Evidenced by a capacitance of 5080 mF·cm-2 at a current density of 6 mA cm-2 in a 6 M KOH electrolyte, the membrane's potential extended beyond oil-water separation. This work not only introduces a cutting-edge oil-water separation membrane and supercapacitor electrode but also offers a promising blueprint for the deliberate engineering of hierarchical structure arrays to cater to a spectrum of related applications.

Hydrogen bond recombination regulated by strongly electronegative functional groups in demulsifiers for efficient separation of oil–water emulsions

Tight oil extraction and offshore oil spills generate large amounts of oil–water emulsions, causing serious soil and marine pollution. In such oil–water emulsions, the resin molecules are bound by π–π stacking and bind to interfacial water molecules via hydrogen bonds, which impede the aggregation between water droplets and thereby the separation of the emulsion. In this study, strongly electronegative oxygen atoms (in ethylene oxide, propylene oxide, esters, and hydroxyl groups) were introduced through poly(propylene glycol)-block-polyether and esterification with acrylic acid to attract negative charges in order to form electron-rich regions and enhance interfacial hydrogen bond recombination. The potential distribution in the demulsifier molecules and their space occupancy were regulated by the polymerization reaction to destroy the π–π stacking interaction between resin molecules. The results show that the binding energies (binding free energy and hydrogen bonding energy) of oxygen-containing demulsifier molecules with water molecules were higher than those of resin molecules with water molecules, resulting in the fission of the hydrogen bonds between resin and water molecules. The introduction of demulsifier molecules that occupied large interfacial space reduced the binding energy between resin molecules from −2176.06 to −110.00 kJ·mol−1. Noteworthy, the binding energy between demulsifier molecules and resin molecules was −1076.36 kJ·mol−1 lower than that between resin molecules (−110.00 kJ·mol−1), indicating the adsorption of the surrounding interfacial resin molecules by the demulsifier molecules and destruction of the π–π stacking between them, thus favoring the collapse of the interfacial structure of the oil–water emulsion and achieving its separation. This study provides important theoretical support for the treatment of oil-contaminated soil and offshore oil spill pollution.

Janus resorcinol-formaldehyde-based membrane with opposite wettability for efficient separation of oil and water emulsion

A resorcinol-formaldehyde (RF)-based Janus membrane was fabricated by casting graphene oxide (GO)-dispersed RF solution on Janus-B side and Cu salt-RF solution on the opposite Janus-A side of an activated carbon fibre (ACF) substrate, and then subjecting the composite material to chemical vapor deposition to form a web of carbon nanofiber (CNF) on the Janus-A side. CNF imparted the super-hydrophobic (water contact angle WCA ∼151°) and super-oleophilic (oil contact angle OCA ∼0°) characteristics, while GO-RF imparted the hydrophilic (WCA 30°) and olephobic (OCA ∼121°) characteristics to the membrane. The microfiltration tests were carried out under different conditions of oil and water feed concentrations (0–15% v/v) and operating pressure (1–3 bar). The super-hydrophobic side showed 99.75% water rejection efficiency and the initial permeate flux of 1020 Lm−2h−1 for a 5% (v/v) water-in-oil (W/O) emulsion, while the hydrophilic side showed 99.96% oil rejection efficiency and the initial permeate flux of 380 Lm−2h−1 for 5% (v/v) oil-in-water (O/W) emulsion. The material showed good chemical stability in acidic, basic and corrosive media as well as an excellent repeatability under the repeated alternate cycles of pure diesel/water and emulsion post- simple ethanol wash. Considering that the method of fabrication is simple, fast, and scalable, the comparative performance data clearly pitch CNF-RF/ACF/GO-RF ahead of the other membranes discussed in the literature for oil-water emulsion.

Green Synthesis of a Carbon Quantum Dots-Based Superhydrophobic Membrane for Efficient Oil/Water Separation.

The efficient separation of oil and water is a significant challenge worldwide due to the increasing frequency of industrial oily wastewater. Previous work by our group utilizes biological metal-organic framework-based superhydrophobic (S.P) textile fabric for oil/water separation. However, this system is limited due to the low mechanical stability, so there is a need for producing a more robust S.P membrane for oil/water separation. In this study, we report on the synthesis of carbon quantum dots (CQD) from banana leaves via a hydrothermal process and their application in producing a robust S.P coating on textile fabric for oil/water separation. The CQDs were characterized using various techniques including TEM, XRD, absorbance spectroscopy, and the BET method. The TEM images showed that the CQDs were circular in shape with a size of 4.4 nm, while the XRD micrograph indicated that the CQDs were crystalline in nature. The UV-vis graph showed a peak at a wavelength of 278 nm, suggesting strong absorption in the ultraviolet region. The BET-specific surface area of the prepared CQDs is 845 m2/g, with a pore volume of 0.33 cm3/g, and a mean pore diameter of 1.62 nm. We examined the surface wettability, morphology, composition, oil absorption capacity, oil/water separation performance, flux rate, chemical stability, and mechanical stability of the S.P membrane. Our findings indicate that the developed CQD-based S.P membrane possesses excellent S.P properties, displaying high water contact angles of 163° and low water sliding angles of 1°. The membrane demonstrated superior oil absorption capacity, separation efficiency, and flux rate towards three different oils-petroleum ether, n-hexane, and silicone oil. Petroleum ether has the highest separation efficiency (99.5%), and flux rate (13,500 L m-2 h-1), while silicone oil has the lowest. However, silicone oil has the highest absorption capacity (218.9 g/g) and petroleum ether has the lowest (194.8 g/g). For the absorption capacity and separation efficiency, a one-way ANOVA test was conducted. The statistical analyses revealed significant differences in absorption capacity and separation efficiency for the three oils, highlighting the efficacy of the superhydrophobic membrane for tailored oil/water separation. Additionally, the S.P membrane exhibited good mechanical (the membrane maintains its superhydrophobicity until an abrasion length of 850 cm) and chemical stability (the membrane maintains its superhydrophobicity in pH range 1-13), withstanding abrasion and immersion in solutions of varying pH values. The CQD-based S.P membrane shows great potential as a promising material for oil/water separation applications, with excellent performance and stability under various environmental conditions.

Anticorrosive superhydrophobic high-entropy alloy coating on 3D iron foam for efficient oil/water separation

Oil-spill remediation requires low-cost, high-efficiency, and operationally flexible oil-water separators, particularly those with superior corrosion resistance to extend their service life. Superhydrophobic 3D metallic foams are increasingly attracting tremendous attention due to their excellent mechanical stability and promising applications for continuous in-situ separation. Hence, superhydrophobic iron foams were fabricated via cyanide-free electrodeposition of a ZnFeCoNiMn high-entropy alloy (HEA) coating followed by non‑fluorine surface modification with tetradecanoic acid. Fluffy microspheres with hierarchical micro/nanostructure on the superhydrophobic HEA coating contributed to the superhydrophobicity of 3D iron foam. These foams exhibited highly efficient separation of oil and water even under violent stirring (700 rpm). Moreover, they achieved excellent anti-corrosion performance, with a decline in corrosion rate from 14.95 to 0.27 mm·a−1 in a 3.5 wt% NaCl solution, making it perfect for the harsh sea environment.

Superhydrophobic Sponge for Highly Efficient Separation of Both Stratified and Emulsified Oil–Water Mixtures

Efficient separation of oil–water mixtures, particularly homogeneous and stable emulsions, has always been an industrial challenge. Herein, we report a facile, cost-effective procedure for fabricating superhydrophobic melamine sponges using a single solution–immersion process. The modified sponge has stable superhydrophobicity owing to the synergy of triple hydrophobic mechanisms with a maximum water contact angle of 158°. As an absorbent, the modified sponge block exhibits high porosity, outstanding absorption capacity, excellent mechanical properties, and superior physical and chemical stability, enabling its use for the separation of stratified oil–water mixtures via repeated absorption–extrusion processes with a separation efficiency of nearly 100%. Furthermore, as a filter, the crushed, modified sponge powders exhibit a demulsification efficiency ranging from 97.65 to 99.33% for the separation of ideal water-in-oil emulsions under gravity. Finally, the feasibility of these sponges for oilfield applications is established through the demonstration of the continuous separation of an emulsion of brine in crude oil using the modified sponge powders in conjunction with an in-house built apparatus. This work may open a viable pathway for the efficient separation of both stratified and emulsified oil–water mixtures via wettability, and provide a novel strategy for the reuse of waste sponges.

Laser Electrochemical Deposition Hybrid Preparation of an Oil-Water Separation Mesh with Controllable Pore Diameter Based on a BP Neural Network.

With the increasing problem of water pollution, oil-water separation technology has attracted widespread attention worldwide. In this study, we proposed laser electrochemical deposition hybrid preparation of an oil-water separation mesh and introduced a back-propagation (BP) neural network model to realize the regulation of metal filter mesh. Among them, the coating coverage and electrochemical deposition quality were improved by laser electrochemical deposition composite processing. Based on the BP neural network model, the pore size after electrochemical deposition could be obtained only by inputting the processing parameters into the model, enabling the prediction and control of the pore size of the processed stainless-steel mesh (SSM), and the maximum residual difference between the predicted value and the experimental value was 1.5%. According to the oil-water separation theory and practical requirements, the corresponding electrochemical deposition potential and electrochemical deposition time were determined by the BP neural network model, which reduced the cost and time loss. In addition, the prepared SSM was found to achieve efficient separation of oil and water mixtures, reaching 99.9% separation efficiency in a combination with oil-water separation, along with other performance tests without chemical modification. The prepared SSM showed good mechanical durability and the separation efficiency exceeded 95% after sandpaper abrasion, thus, still maintaining the separation ability of oil-water mixture. Compared to other similar preparation methods, the method proposed in this study has the advantages of controllable pore size, simplicity, convenience, environmental friendliness, and durable wear resistance, offering important application potential in the treatment of oily wastewater.

Recombination of hydrogen bonds clipping interfacial film effectively for dehydrated tight oil

Tight oil is an important unconventional oil resource. However, during the extraction process of tight oil, a large amount of tight oil emulsion is generated, combined with offshore oil releases, have caused serious environmental problems. Owing to the high content of resin molecules, which adsorbed the interfacial water molecules in the form of hydrogen bonds, as well as tightly bound resin molecules via π–π stacking, the interface structure is stable; hence, it is difficult to separate oil and water. In this study, the hydrogen-bond energy of O atoms in common groups and water molecules was analyzed, and the efficient separation of oil and water was realized by the regulation of hydrogen-bond energies of the demulsifier molecules and interfacial water molecules. The O atoms in EO, PO, ester group and hydroxyl group were named as Type 1–6 O atoms. The compatibility of the demulsifier and tight oil was improved by the introduction of an aromatic structure, which combined with the tight oil molecules via π–π stacking. At the same time, by the introduction of Types 1–6 O atoms, the electronegativity (Hydrogen bond acceptor ability) of the demulsifier molecules was optimized to improve the hydrogen-bond energy formed between the demulsifier and water molecules effectively; then, the interfacial resin molecules were replaced to form stronger hydrogen bonds with water molecules, weakening the π-π stacking interaction between resin molecules for clipping the interfacial film; thus, the mass-transfer efficiency of water molecules at the oil–water interfacial is enhanced.

Rational Design of High-Flux, Eco-Friendly, and Versatile Superhydrophobic/Superoleophilic PDMS@ZIF-7/Cu3(PO4)2 Mesh with Self-Cleaning Property for Oil-Water Mixture and Emulsion Separation.

In recent years, efficient oil-water separation has gradually become an indispensable part of environmental treatment. Superhydrophobic/superoleophilic materials with excellent self-cleaning performance are urgently required and remain challenging in the investigation of practical, rapid, and efficient separation of oil-water mixture and emulsion, especially those with robust surfaces that can be used in harsh conditions. In this work, a novel superhydrophobic/superoleophilic material was first fabricated by in situ constructing PDMS@ZIF-7/Cu3(PO4)2 hierarchical architectures on a copper mesh, which was adopted as a high flux and efficient separation material for gravity-driven separation of oil-water mixture as well as emulsion. The introduction of crucial Cu3(PO4)2 nanosheet interlayers created the ideal hierarchical structures and serve as partial templates for the subsequent in situ growth of hydrophobic ZIF-7 nanosheets. An improved superhydrophobicity (CA = 155°), permeation flux (102,000 L m-2 h-1), and preferred self-cleaning property were thus achieved by such manipulation of the copper mesh. The PDMS@ZIF-7/Cu3(PO4)2 mesh exhibited exceptional separation efficiency for diverse oil-water mixtures and emulsions attributed to the superhydrophobicity and the demulsification ability and considerable stability to cope with extreme environments including sunlight resistance, low temperature, and corrosion resistance, which prompted its promising applicability in cleaning emulsified wastewater.

Rational design of polymer nanofiber aerogels with aligned micrometer-sized porous structures and their high separation performance

In this article, a new type of pre-oxidized polyacrylonitrile/polyimide (OPAN/PI) nanofiber aerogels (NFAs) with aligned micrometer-sized hierarchical porous structures was fabricated via oriented ice-segregation-induced self-assembly and thermal imidization process. Polyimide was chosen as an adhesive and cross-linker because of its excellent chemical resistance, thermal stability and mechanical strength. The resulted OPAN/PI NFA have good resilience and high hydrophobicity (water contact angle 136.0°), ultralow density (8.65 mg m−3), which can be used as good oil absorbents and efficient separation of oil and water. The optimized OPAN/PI NFAs can collect various oily solvents with high absorption capacities up to 135 times of their own weight. Moreover, surfactant-stabilized water-in-oil emulsions and oil/water mixture can be fully separated under gravity driving and the filtration efficiency has only 1% loss after 20 separation processes. The elution flux can be up to 8.7 × 105 L m−2 h−1. This work opens up the avenue of exploring novel for application in the field of oil/water separation.