Efficient Oil-water Separation Research Articles

Biomimetic stable cellulose based superhydrophobic Janus paper sheets engineered with industrial lignin residues/nano-silica for efficient oil-water separation

The preparation of degradable, stable, acid- and alkali-resistant oil/water separation materials from renewable biomass resources is a vast challenge as well as vital for sustainable development. Inspired by the asymmetric wettability of lotus leaf, a brand-new type of cellulose-based Janus paper sheets with anisotropic wettability was successfully designed and engineered with industrial lignin residues and nano-silica. By easy spraying of coatings to construct hierarchical networks, the papers achieved robust superhydrophobicity in a variety of acidic and alkaline conditions (pH = 3–11) with a water contact angle about 153°. Benefiting from the lipophilicity of lignin and the hydrophilicity of cellulose, Janus paper sheets were endowed an excellent oil-water separation efficiency. It reached a maximum flux of 654.46 L·m−2h−1 of dichloromethane in the solvent-water mixture. Furthermore, the mechanical properties, folding and tearing resistance of the obtained materials were significantly improved due to the splendid interfacial adhesion, rendering them satisfied stability and durability. The oil-water separation efficiency of the Janus paper sheets was maintained at 90% over 8 recycles. In contrast to cumbersome oil-water separation materials, the proposed Janus paper sheets can operate as an efficient, stable, acid- and alkali-resistant, abrasion-resistant biodegradable material to effectively absorb heavy oils and waste organic solvents. A novel application possibility is provided by such an environmentally friendly, reliable, and efficient preparation process for oil-water separation.

Superhydrophilic/superoleophobic GO@CoSx photocatalytic membranes with excellent antifouling properties for efficient oil-water separation and organic pollutant degradation

With the development of industry, water resources have been seriously polluted, posing a great threat to human health and ecological development, and it is urgent to realize the efficient treatment of sewage-containing wastewater. The CoSx modified by thioacetamide grew in the interlayer of graphene oxide, which provided the composite membrane with self-cleaning ability, and at the same time enlarged the interlayer channels, which resulted in the flux and hydrophilicity significantly better than that of GO, and the retention rate of different types of oil-in-water emulsions was above 99 %. Encouragingly, the GO@CoSx-activated PMS system exhibited extremely high degradation performance for methylene blue. After 5 cycles, the flux of the composite membrane to the oil red-petroleum ether-oil-in-water emulsion under the light condition was higher than that under the dark condition, and the retention rate was kept at 99.93 %, with excellent antifouling performance. The composite membrane showed good degradation of methylene blue under alkaline conditions (99.84 %) and excellent removal of oil red-petroleum ether-oil-in-water emulsion under strong acid/alkaline conditions (99.37 %). The composite membrane has good chemical stability and mechanical properties for long-term use. This study will provide a new idea for the separation of oil-water emulsions, which has a broad application prospect.

A direct electrospinning strategy prepared series of coal-derived nanofibers for efficient oil-water separation

Oily wastewater treatment is an arduous global problem. Electrospinning has great potential applications in construction of durable and highly efficient oil–water separation membranes. In this article, low-cost coal was directly incorporated into the fiber skeleton to enhance the roughness of C-NF and impart hydrophobicity (WCA = 130°). The gravity-driven oil flux exceeded 600 L m−2h−1 with a separation efficiency of 96.5 % for emulsions. However, successful mitigation of surface fouling while maintaining efficient flux stability and separation efficiency remains a challenge for C-NF membranes. Herein, we adjusted the diameter of fiber membranes by controlling the heat treatment process and then introduced a vapor deposition technique to achieve super-hydrophobicity (＞150°) and super-lipophilicity (0°) in the obtained C-NFOH and C-NFCH fibers. As a result, these fibers exhibit high flux and separation efficiency for gravity-driven separation of oil/water mixtures and water-in-oil emulsions. Particularly, the C-NFOH membrane exhibits a superior ability to separate water-in-oil emulsions with an efficiency of up to 99.5 %, surpassing that of both C-NF (96.5 %) and C-NFOH (99.2 %) membranes. Furthermore, the robust C-NFOH and C-NFCH membranes exhibit exceptional self-cleaning properties. These membranes are fabricated via direct electrospinning of coal, offering novel opportunities for advanced membrane design in the realm of oil/water emulsion separation.

Preparation of Highly Adhesion Hydrophobic Membrane and Superhydrophobic Membrane via Electrospinning

Membranes with superhydrophobicity have attracted much attention in recent years for improving self‐cleaning in practical applications. In this study, highly adhesive hydrophobic membranes and superhydrophobic membranes are prepared and used for preciously rare droplets transportation and efficient oil–water separation separately. The two types of membranes with different applications are prepared by electrospinning and the morphology and structures of the electrospinning membranes are adjusted by regulating a series of parameters including voltage, flow rate, and the diameter of the spinning needle. The as‐prepared membranes with apparent superhydrophobicity are fluorine‐free, environmentally friendly materials and realize effective and rapid oil–water separation; moreover, the membranes exhibit excellent adhesivity when measured by the video–optical contact‐angle system, and the maximum adhesion amount is 80 μL. The two membranes reported here are easily fabricated and reproducible, with adhesive and superhydrophobic properties, respectively. So, it is envisioned that the membrane has the potential to be used in a variety of practical applications such as the development of robots that require nondestructive liquids transportation, efficient oil–water separators, and so on.

Cellulose acetate superhydrophobic coatings for efficient oil–water separation using a combination of electrostatic spraying and chemical vapor deposition

AbstractThe efficient and simple separation of oil–water mixtures has been a global challenge due to the growing problem of oily wastewater. To address this issue, various materials with special wetting properties and functionality have been developed in the past decades for oil–water separation. In this study, a superhydrophobic cellulose acetate (CA) functional coating was prepared by electrostatic spraying of CA and chemical vapor deposition of methyltrichlorosilane (MTCS) on a stainless steel mesh (SSM). Water contact angle in air (WCA) of the resulting coating is154° or more, and oil under water contact angle (UWOCA) is 0°. Simultaneously, the separation flux of the resulting coating for oil–water mixtures is as high as 23977.77 L·m−2·h−1, with separation efficiencies exceeding 99%. Due to its excellent water repellency, the CA functional coating can effectively separate oil and water, and can be easily dried for continuous use. Furthermore, the CA functional coating exhibits good stability in salt solutions and acidic environments, making it an ideal material for addressing oily wastewater challenges.Highlights The coating obtained by electrostatic spraying and CVD was superhydrophobic. The separation flux and separation efficiencies of coatings is 23977.77 L·m−2·h−1 and 99%. Coatings remain stable under polar environment conditions (pH = 2–12 and NaCl = 1–3 mol/L).

Recyclable porous polyurethane sponge for highly efficient oil–water separation

AbstractOil spills and chemical leakages have caused severe environmental problems. Physical absorption of the spilled oils and chemical reagents by absorbing materials is an efficient and economical approach to solve these problems. Herein, we have prepared a porous thermoplastic polyurethane (TPU) sponge by combining the thermally induced phase separation method with the selective dissolution of water‐soluble PEG components. The selective removal of PEG components from the walls of TPU sponges could increase the intensities of free volume holes and surface areas of TPU sponges. The content of free volume holes and surface areas of TPU sponge reached its maximum with the TPU/PEG ratio of 1:1. The increased roughness could improve the absorption capacities of TPU sponges for various oils/organic solvents. Moreover, due to its excellent compressibility, this TPU sponge could be reused 20 times with little loss of saturated absorption capacity. In addition, this TPU sponge exhibited excellent separation ability for the toluene from the toluene/water mixture and emulsion. In all, we have developed a facile method to prepare TPU sponge absorbent with excellent absorption performance, which holds great potential in the application of large‐scale oil/water separation.

Superhydrophilic/underwater superoleophobic PVDF ultrafiltration membrane with pH-responsive self-cleaning performance for efficient oil-water separation

The treatment of various oily wastewaters generated in human production and life has been a huge challenge in recent years. Responsive materials for controlled wettability surface have a great potential for oil-water separation. Inspired by the superior pH-responsive of poly (2-(N, N′-dimethylamino) ethyl methacrylate) (PDMAEMA), a pH-responsive self-cleaning PVDF ultrafiltration membrane containing both carboxyl and tertiary amine groups were prepared by a simple grafting and co-blending method. The membrane fabrication process consisted of introducing 3-Dimethylaminopropylamine (DMPA) into the SMA side chain, resulting in the creation of the amphiphilic polymer DMPA@SMA. This polymer was then mixed with PVDF to produce DMPA@SMA/PVDF membranes. The optimized DMPA@SMA/PVDF membranes showed excellent superhydrophilicity/underwater superhydrophobicity, with a water contact angle of 0° and an underwater oil contact angle higher than 150° for crude oil. These endowed the as prepared membrane with a high pure water flux of 852 L·m−2·h−1 and anti-crude-oil-adhesion property. The separation efficiency exceeded 98% for various surfactant-stabilized oil-in-water emulsions, whether it’s positively charged emulsion or negatively charged emulsion. More interestingly, the carboxyl and tertiary amine groups presented the membrane with pH responsivity, and the membrane surface can be triggered by acid or alkali with self-cleaning performance. Strategy proposed in the present work offers a convenient and effective way to prepare membranes treating oil-in-water emulsions with either negative or positive charges.

Hydrophilic-to-hydrophobic conversion of polyamide 6-based mat via polyvinylidene fluoride nanofiber integration with enhanced oil-water separation

This study presents a unique technique for fabricating a highly effective hydrophobic polyamide 6 (PA6)-based nonwoven mat with remarkable performance in hydrophobicity and oil-water separation. Utilizing a ternary blend system of polypropylene (PP)/PA6/polyvinylidene fluoride (PVDF) based on Harkin's theory and employing an in-situ fibrillation process, a distinctive micro-nano hierarchical structure is achieved. The removal of the PP matrix results in a nonwoven mat composed of bimodal PA6 microfibers surrounded by PVDF nanofibers. Water contact angle measurements revealed micro-nano hierarchical structure in the mat-induced hydrophobicity on the intrinsically hydrophilic PA6. Further optimization of the PP removal process enhances the hydrophobicity of the micro-nano fibrillar structure. The mat also demonstrates outstanding efficiency in separating oil and water, with an impressive oil-water separation efficiency of up to 97.4%. This scalable fabrication technique opens significant opportunities for the utilization of hydrophobic PA6 nonwoven mats in diverse industries, including textiles and other sectors where water repellency is crucial. Furthermore, these hydrophobic PA6 nonwoven mats hold great potential for sustainable applications in environmental settings, addressing the growing need for both hydrophobicity and efficient oil-water separation solutions.

Recent advances on the fabrication of superwettable layered double hydroxides materials for oil–water separation

Fast industrialization and infrastructural development have increased the use of fossil fuels, leading to frequent oil spills during mining and/or marine transportation produces oily wastewater. Everywhere in the world, oil spills poses a serious global environmental problem and is considered an environmental disaster. Hence, there is a need to find an efficient way to treat oil–water separation, and a recent approach is through the use of functional materials. Emerging studies suggest that superhydrophobic materials have great potential for the separation of oil–water. In this review discusses the potential of superwettable materials, especially superwettable layered double hydroxides (LDHs) materials for efficient oil–water separation. Superwettable LDHs demonstrate various mechanism for water and oil removal, such as superhydrophilicity/superoleophobicity, superhydrophobicity/superoleophilicity, sedimentation/flocculation or adsorption, and oil mopping. Also this review highlight LDHs capability and their role in achieving superwettability during oil–water separation, addressing challenges and briefly discusses the future research direction in this promising area.

In situ reaction enabled surface segregation toward dual-heterogeneous antifouling membranes for oil-water separation

Fabricating membranes with superior antifouling property and long-term high performance is in great demand for efficient oil-water separation. Herein, we reported a reaction enabled surface segregation method for antifouling membrane fabrication, in which the pre-synthesized fluorinated ternary copolymer Pluronic F127 was coordinated with Ti4+ as segregation additive in the membrane casting bath. Additionally, tannic acid was utilized to enhance the self-assembly of the copolymer in the coagulation bath, and freshly-biomineralized TiO2 was anchored into the membrane surface through hydrogen bond. A hydrogel layer was constructed onto the membrane surface with synergistically tailored heterogeneous chemical composition and heterogeneous geometrical roughness. The dual-heterogeneous membrane exhibited hydrophilic and underwater superoleophobic features, resulting in high water flux (621.7 L m−2 h−1) at low operation pressure of 0.05 MPa and an excellent antifouling property (only 4.8% flux decline during 24-hour filtration). In situ reaction enabled surface segregation method will accelerate the development of antifouling membranes for oil-in-water emulsion separation.

In-situ electrostatic self-assembly superhydrophilic UiO-66-NH2@h-PPS membranes for highly efficient oil-water emulsion separation

Highly efficient treatment of oil-water emulsions in severe environments (organic solvents, strong acids) is recognized as a challenging subject. Polyphenylene sulfide (PPS) is an ideal membrane material with superior thermal stability as well as chemical resistance that is expected to settle this challenge. However, the hydrophobicity of PPS (h-PPS) membrane inherently prevents its efficient treatment of oil-in-water (O/W) emulsions. In this study, superhydrophilic modification of PPS substrates was achieved by in situ electrostatic self-assembly of hydrophilic Zr-MOFs to obtain UiO-66-NH2@h-PPS membranes. The introduction of UiO-66-NH2 crystals constructed the micro/nanoscale hierarchical structure for the substrate, which transforms the PPS substrate from a hydrophobic to a superhydrophilic state (water droplets require only 0.6 s to be completely immersed in the membrane). Meanwhile, the UiO-66-NH2@h-PPS membranes gain under-water superhydrophobicity (the under-water oil contact angle exceeds 150° for toluene, hexane, dichloromethane, and carbon tetrachloride, of which toluene reaches 163.1°), thereby improving wettability selectivity and decreasing oil adhesion, permitting the fabricated UiO-66-NH2@h-PPS membranes to effectively separate different types of O/W emulsions. The UiO-66-NH2@h-PPS membranes acquire excellent permeate fluxes (for the surfactant-free toluene-in-water emulsion, it reaches up to 7638.1 L m−2 h−1) and separation accuracy (99.1% oil rejection). Moreover, the UiO-66-NH2@h-PPS membrane exhibited outstanding harsh environment resistance. Interestingly, the combination of UiO-66-NH2 and h-PPS substrate was applicable to degrade the organic compound in water, and the degradation efficiency of the methylene blue achieved 85.7% under visible light within 120 min. In summary, loading Zr-MOFs onto h-PPS substrates provides a novel strategy for the efficient treatment of wastewater under complex conditions with great potential for practical applications.

Photoswitchable and reusable superhydrophobic/hydrophilic TiO2-coated stainless-steel mesh as oil–water separator

This study fabricated a superhydrophobic/hydrophilic stainless-steel mesh with a TiO2-coated surface for efficient oil–water separation. The mesh manifested both hydrophobic and hydrophilic properties upon incorporating fluorine- and amine-containing silanes, respectively. The photoswitching speed and recovery of surface properties were evaluated by adjusting the UV irradiation period. Additionally, the mesh was subjected to ultrasonic treatment to enhance the photoswitching speed. After alternating UV irradiation and ultrasonification treatments, the variations in contact angle confirmed the feasibility of reversible surface conversion: 158° → 15° → 149.4° → 9.1° → 146.8° → 8.4° → 147.3°. Furthermore, the oil–water separation efficiency of the fluorine-modified mesh was assessed using water and n-hexane solutions. Over eight cycles, the hydrophobic/hydrophilic mesh achieved an average separation efficiency of 95.3% and 96.7%, respectively. The separation process occurred within approximately 5 s. Thus, this study proposed a comprehensive approach for developing a single superhydrophobic mesh capable of facile and rapid photoswitching between hydrophilic and hydrophobic properties. The developed mesh offers precise filtration, durability, and reusability, contributing to sustainable oil–water separation processes.

Superhydrophobic Thermoplastic Polyurethane Foam Fabricated by Phase Separation and Silica Coating for Oil-Water Separation.

Oil spills and the presence of oily wastewater have resulted in substantial ecological damage. Superhydrophobic polymer foam with selectivity and adsorption capacity is a promising candidate for efficient oil-water separation. In this study, a method that combines phase separation and silica coating to produce superhydrophobic thermoplastic polyurethane (TPU) foam is proposed. The TPU foam demonstrates superhydrophobicity with a water contact angle of 155.62°, and exhibits a maximum saturated adsorption capacity of 54.11gg-1 . Furthermore, the foam can be utilized as a filter for oil-water separation, maintaining its filtration efficiency (41.2m3 m2 h-1 ) even after ten filtration cycles.

Double network cross-linked hydrogel coating membrane with photocatalytic self-cleaning performance for efficient oil-water separation

Oil-water separation is one of the most attractive areas in the field of energy and the environment. However, the synthesis of oil-water separation membranes with high separation efficiency and anti-fouling via simple methods is still a challenge. In this work, a double network with tannic acid and g-C3N4 cross-linked gelatin hydrogel coating membrane was prepared via ultrasound and coating. The prepared hydrogel had excellent mechanical properties and swelling resistance and also endowed the membrane with underwater superoleophobicity. For stratified oil-water mixtures, the separation flux achieved 40,355 ± 1957 L·m−2·h−1 and separation efficiency higher than 99 %. Moreover, after 40 cycles, there was no decrease significantly in separation performance. For oil-in-water emulsions, the separation efficiency is >99.90 % under gravity. The adsorption of MB by the GE-CNTA-PP membrane conformed to a pseudo-first-order kinetic process (R2 = 0.99906), which was consistent with the Langmuir isothermal adsorption model (R2 = 0.99932). The contaminated membrane could self-clean via photocatalytic reaction, which mechanism was explained through theoretical investigation of the band structure of g-C3N4 by DFT. Due to these obvious advantages, the practical application of the gelatin-based hydrogel membrane in the purification of oily wastewater is promising.

Urchin-like fluorinated covalent organic frameworks decorated fabric for effective self-cleaning and versatile oil/water separation

Oil contamination and industrial organic pollutants emission have been a serious problem affecting the ecological and residential environment. Membrane-based separation shows great application prospect due to its low-cost, environmental-friendly and easy operation. Therefore, the development of efficient oil-water separation membranes is highly desirable. Herein, a fabric filter with superwettability was prepared by coating urchin-like fluorinated covalent organic frameworks (COFs) on fabric, which was well utilized in filtering immiscible oil-water mixture and surfactant-stabilized water-in-oil emulsion driven only by gravity for the first time. The as-prepared COF fabric filter (defined as fabric@u-FCOF) possessed many outstanding properties, including superhydrophobicity with the water contact angle of approximately 151.6°, satisfactory resistance for alkaline, acidic and saline environments, as well as superior mechanical durability under harsh conditions. Because of the super-micropore of fabric@u-FCOF and the nanopore in the COF coating, the obtained fabric@u-FCOF exhibited excellent performances in terms of separation efficiency and permeability, in which the oil flux was up to 16964 L·m−1·h−2 and separation efficiency for the mixed o-dichlorobenzene/water was higher than 99.4%. In addition, the fabric@u-FCOF also showed excellent self-cleaning performance due to the micro/nano hierarchical structure of its surface. These excellent properties make it an ideal candidate for applications of oil/water separation and water purification.

Superhydrophobic DTES-SEP/SiO2@PDMS coated sponge and stainless steel mesh for efficient oil and water separation

The exploitation of offshore oil will inevitably cause oil leakage, which not only affects the ecological environment but also threatens the balance of the marine ecosystem. Therefore, new materials for efficient oil-water separation need to be continuously researched. In this paper, dodecyltriethoxysilane (DTES) was used to hydrophobically modify meerschaolite (SEP) and silicon dioxide (SiO2) nanoparticles. DTES-SEP/SiO2@PDMS coatings were successfully prepared on the surface of sponges and stainless steel meshes by immersion in the presence of polydimethylsiloxane (PDMS). The coating has a water contact angle of up to 153°. It exhibits high wettability. It is worth noting that the adsorption capacity of coated sponges to various oils and organic solvents is 27–77 times their own weight. More importantly, the prepared coatings exhibit excellent stability in strong corrosive solutions. In addition, the mechanical properties of DTES-SEP/SiO2@PDMS coating remain stable after abrasion and peeling. At the same time, the coating shows excellent resistance to grit, methylene blue solution and clay. This research provides a reliable way to achieve efficient oil-water separation.

Fabrication and characterization of superhydrophilic graphene-based electrospun membranes for efficient oil-water separation

This research article investigates the fabrication of superhydrophilic graphene-based electrospun membranes for efficient oil-water separation. The study utilizes cellulose acetate (CA) as the base material for membrane fabrication, employing an electrospinning technique followed by the electrohydrodynamic atomization of graphene oxide (GO) to enhance their hydrophilicity. The surface morphology, water contact angle, and Fourier Transform Infrared (FTIR) spectra of the fabricated membranes were analyzed to assess their properties. The membrane characterization techniques revealed the successful integration of GO nanosheets on the surface of the highly porous interconnected nanofibrous matrix. The modified membranes exhibited superhydrophilicity and underwater oleophobicity. The water contact angle of the optimized GO-based electrospun CA membrane was reduced from 110° to zero within 3 s. The performance of the membranes was evaluated through oil-water separation experiments using different types of oils (such as toluene, n-decane, and hexane) in water. The results demonstrated that the graphene-based optimized membranes exhibited high separation efficiency (3820 LMH), with a water permeation flux as high as 65.5 % compared to CA membranes (2308 LMH). The efficiency of separation while using all three different oils with DI water was calculated to be >99.9 %. The study provides valuable insights into the use of graphene-based membranes for oil-water separation and highlights the potential of the electrohydrodynamic atomization technique for the surface modification of membranes. The developed membranes have great potential applications in various industries, including oil and gas, chemical, and wastewater treatment.

Non-Wettable Microporous Sheets Using Mixed Polyolefin Waste for Oil-Water Separation.

Mixed polyolefin-based waste needs urgent attention to mitigate its negative impact on the environment. The separation of these plastics requires energy-intensive processes due to their similar densities. Additionally, these materials cannot be blended without compatibilizers, as they are inherently incompatible and immiscible. Herein, non-wettable microporous sheets from recycled polyethylene (PE) and polypropylene (PP) are presented. The methodology involves the application of phase separation and spin-casting techniques to obtain a bimodal porous structure, facilitating efficient oil-water separation. The resulting sheets have an immediate and equilibrium sorption uptake of 100 and 55 g/g, respectively, due to the presence of micro- and macro-pores, as revealed by SEM. Moreover, sheets possess enhanced crystallinity, as evidenced by XRD; hence, they retain their structure during sorption and desorption and are reusable with 98% efficiency. The anti-wetting properties of the sheets are enhanced by applying a silane coating, ensuring waterless sorption and a contact angle of 140°. These results highlight the importance of implementing sustainable solutions to recycle plastics and mitigate the oil spill problem.

Metal–Organic Frameworks-Based Membranes with Special Wettability for Oil–Water Separation: A Review

The presence of oily wastewater poses a significant threat to both the ecological environment and public health. In order to solve this problem, the design and preparation of an efficient oil–water separation membrane is very important. Metal–organic frameworks (MOFs) are currently a promising material for oil–water separation due to their tunable wettability, adjustable pore size and also low density, high porosity, and high surface area. Therefore, MOFs-based membranes show great potential in the field of oil–water separation. In this paper, we first introduce the oil–water separation mechanism and then comprehensively summarize the common preparation methods of MOFs-based oil–water separation membranes and the research progress of different MOFs-based membranes, including the ZIF series, UiO series, MIL series, etc. Finally, we also analyze the challenges faced by MOFs-based membranes in oil–water separation and provide an outlook on their future development and application.

One-pot preparation of environmentally friendly, high demulsification rate and novel functional magnetic demulsifier: Used for oil and water separation in crude oil emulsion

In this paper, a novel functional magnetic nano-demulsifier with efficient oil–water separation and recyclability was prepared by one-pot method. Magnetic fluorinated polyether composite demulsifier (Fe3O4@C-F) was prepared by combining Fe3O4 as magnetic matrix with carbon nanospheres and grafting fluorinated polyether. The morphology and structure of the composites were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that carbon nanospheres and fluorinated polyether were successfully compounded on Fe3O4, and the crystallinity of the composites was improved. The demulsification experiment and recovery performance test were carried out with the self-made crude oil emulsion. The main factors affecting the demulsification performance of demulsifier and its demulsification mechanism were discussed. The results showed that the demulsification effect of Fe3O4@C-F was the best when the dosage was 600 ppm, 65 °C, 120 min and pH value was 6. The demulsification rate could reach 96.68%, and the oil–water interface was clear. Fe3O4@C-F had magnetic response, and could be recycled and reused 5 times from two-phase system under external magnetic field. The application of carbon materials in the field of oil–water separation has injected a new power source for the application of carbon nanomaterials in the field of demulsifiers.