Oil-water Mixture Research Articles

Facile preparation of poly(melamine formaldehyde) sponge/bacterial nanocellulose composite for oil-water separation

The treatment of a large amount of oil-water mixture generated by oil leakage accidents is an environmental issue that cannot be ignored. Achieving fast and efficient oil-water separation is a goal pursued by both academia and industry. In this paper, poly(melamine formaldehyde) (PMF) sponges were modified by the hydrophilic bacterial nanocellulose (BNC) through mild and facile conditions. With increasing the concentration of BNC dispersion used, the pore size of the composite decreases. The water contact angle of the obtained PMF/BNC composite surface is 0° or so, and the underwater oil contact angle is greater than 150°. Based on its hierarchical pore structure, hydrophilicity and oil repellency, the PMF/BNC composite exhibits excellent oil-water separation efficiency and water treatment flux for layered oil-water mixture (>1.0×107L/(m2·h·bar)). In addition, the PMF/BNC composite also exhibits high water treatment flux and oil-water separation efficiency (> 95%) for oil-water emulsion with and without surfactant. Stacking several composite slices could achieve higher oil-water separation efficiency.

A facile strategy for improving the hydrophobicity and photo-thermal conversion capability of biochar and its application in the absorption of hazardous chemicals and viscous oil

Biochar is considered as a promising adsorbent due to its unique porous structure, large surface area and lightweight nature. In this study, pomelo peel was used as raw material, and graphene oxide was introduced as a functional material. High-temperature carbonization was employed to achieve simultaneous carbonization of pomelo peel and thermal reduction of graphene oxide, resulting in the preparation of a porous sponge-like biochar with high hydrophobicity, thermal stability and photothermal conversion capability. This biochar was successfully applied to the efficient separation of various oil–water mixtures, demonstrating excellent cyclic adsorption stability. Furthermore, by harnessing its photothermal conversion effect, efficient absorption of viscous oil product was achieved. This study proposes a facile biochar preparation strategy that can expand its application in the field of oil spill emergency treatment and promote the utilization of agricultural waste.

Effect of transglutaminase on ovalbumin emulsion gels as carriers of encapsulated probiotic bacteria.

The use of emulsion gels to protect and deliver probiotics has become an important topic in the food industry. This study used transglutaminase (TGase) to regulate ovalbumin (OVA) to prepare a novel emulsion gel. The effects of OVA concentration and the addition of TGase on the microstructure, rheological properties, water-holding capacity, and stability of the emulsion gels were investigated. With the addition of TGase and the increasing OVA, the particle size of the emulsion gels decreased significantly (P < 0.05). The gels with TGase exhibited greater water holding, hardness, and chewiness to some extent by forming a more uniform and stable system. After simulated digestion, the survival rate of Bifidobacterium lactis embedded in OVA emulsion gels improved significantly in comparison with the oil-water mixture as a result of the protective effect of the emulsion gel encapsulation. By increasing the OVA content and adding TGase, the rheological characteristics, stability, and encapsulation capability of the OVA emulsion gel could be enhanced, providing a theoretical basis for the use of emulsion gels to construct probiotic delivery systems. © 2023 Society of Chemical Industry.

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.

Controllable process to construct robust superhydrophobic membrane with tunable pore size for efficient separation of oil-water mixtures and emulsions

The increase in the discharge of industrial oily wastewater poses a threat to the environment and human health. Thus, the treatment of oily wastewater has become a focus of current research. The superhydrophobic surface derived from the lotus effect provides an effective direction for oil-water separation. Based on this, the authors reported a tunable superhydrophobic stainless steel separation mesh with a water contact angle of 155° through simple electrodeposition and modification with a fluorine-free modifier. The separation mesh with different surface morphology, by controlling different electrodeposition time and current, is able to achieve oil-water separation with super flux up to 51561 L/(m2·h) in heavy oil/water mixture and high-efficiency over 99.5% in water-in-oil emulsion. This controllable process constructs superhydrophobic membrane with tunable pore size, which is capable of separating heavy oil/water mixtures and water-in-oil emulsions depending on the process. This proposal is suggestive in the field of oil-water separation.

Multifunctional amphibious superhydrophilic-oleophobic cellulose nanofiber aerogels for oil and water purification

Aerogels are of a popular choice for oil-water separation and water purification due to their attractive properties, such as lightweight, large surface area, and high porosity. Developing robust aerogels with multifunctional characteristics is highly desirable but remains challenging nowadays. Herein, we develop a facile one-pot condensation strategy for the fabrication of superhydrophilic-oleophobic (SHI-OP) composite aerogels using cellulose nanofibers (CNF), 3-glycidy-loxypropyl trimethoxysilane (GPTMS), polyethyleneimine (PEI) and fluorine-contained compound (FS-60). The resulted aerogels exhibit a directional lamellar structure with interconnected macropores, super-lightweight with high porosity of 98.30 % and low density of 0.0256 g·cm−3. Also, the aerogels are mechanically durable against repeated compression. Meanwhile, the amphibious SHI-OP feature of the composite aerogels in both air and water states enables them to not only absorb trace amount of water from contaminated oils, but also separate oil-water mixtures with separation efficiency of over 99 % and high permeation flux of over 9060 L/m2·h. Moreover, the aerogels also show excellent dye adsorption capability and reusability toward anionic dyes with a maximum adsorption capacity of 1245.68 mg/g. Such robust and multifunctional aerogels with special surface wettability provide good opportunity for liquid purification and dye-containing wastewater treatment.

Polyhydroxy phenolic resin coated polyetherimide membrane with biomimetic super-hydrophily for high-efficient oil–water separation

In terms of treating the problem of oily wastewater, membrane separation technology has always been a simple and efficient method of oil–water emulsion separation. Inspired by the hydrophilic bumps of the desert beetle, the polyetherimide (PEI) fiber membrane with super-hydrophilic/underwater super-oleophobic properties was prepared by electrospinning and subsequent seeded aggregation strategy of resorcinol (R) and formaldehyde (F). The membrane (PEI@RF) demonstrates pearl necklace-like structures and good antifouling properties, oil–water separation performances, as well as good stabilities in a variety of environments (immersed in water at high/low temperature, and in acid/alkali/salt solutions). More importantly, the as-prepared membrane exhibits excellent performance for various kinds of oil–water mixtures separation, and the corresponding separation fluxes and efficiencies are above 2600 L/m2·h and 99 %, respectively.

The methodology for calculating the apparent water absorption index from test injection data

After the oilfield enters the medium-high water content period, the treatment problem of produced water becomes more and more prominent, and the same-well injection technology can realize the oil-water separation of the produced fluid at the well. The separated water is injected back into the oil reservoir by the injection pump, while the oil-water mixture with higher oil content is lifted to the surface by the extraction pump. However, once the tampering operation is carried out on the production layer, the fluid production capacity of the layer cannot be judged, and it is impossible to determine the reasonable production allocation of the injection and recovery layer. Moreover, in the normal production process, the production tubing can not be taken out normally, so it is difficult to determine the production capacity after blocking by logging method. Therefore, it is necessary to carry out theoretical research on the production capacity of the same injection and recovery wells after tampering according to the method of reservoir engineering, so as to provide a theoretical basis for the reasonable production allocation in the field.

Synthesis of nanocomposites of montmorillonite with carbon nanotubes as a potential material for water purification

The main goal of this research is to create nanocomposites based on unmodified and iron-modified (FeNP) montmorillonite (Mt) and carbon nanotubes (CNT) synthesized using the chemical vapor deposition method. The target area for the application of these materials is the creation of water treatment systems. This paper compares the efficiency of the CNT synthesis process on Mt before and after modification with FeNP of different concentrations and provides the characterization of the CNT microstructure and structure using different methods, such as scanning electron microscopy, high-resolution transmission electron imaging, and Raman spectroscopy. For initial verification of properties important for water purification, Mt+CNT and Mt+FeNP+CNT nanocomposites on a carbon nonwoven fabric (CF) are tested in this work. Incubation of the above-mentioned samples in a water–oil mixture reveals complex adsorption dynamics. The CF+Mt+FeNP+CNT sample shows a very good oil adsorption capacity due to its superhydrophobic and oleophilic properties.

Study on the sensitivity of electromagnetic wave to water content of oil-water mixture

Study on the sensitivity of electromagnetic wave to water content of oil-water mixture

Passive fractionating mechanism for oil spill using shear-wettability modulation.

Oil spillage and organic solvent leakage have been a frequent occurrence in recent years, which pose a significant threat not only to the aquatic ecosystems but also result in substantial economic burdens. This has necessitated the search for materials capable of separating oil from water at enhanced efficiency with superior mechanical and thermal properties. In this study, we conduct a set of systematic molecular dynamics simulations to investigate the potential of two-dimensional graphene-like channels under extreme confinement to achieve efficient oil-water separation. Effective modulation of the wetting characteristics of graphene-like surfaces juxtaposed with unconventional flow behavior at the nanoscale unveils differential interaction of water and oil molecules towards the wall, thereby resulting in distinct separation zones for varying compositions of the oil-water mixture. Such separation zones have been observed to be highly correlated with mixture temperature, which provides effective separation pathways across diverse environmental conditions. Our study offers a paradigm shift in oil-water separation strategies, which not only provides deeper insights into the equilibrium and dynamic behavior of a two-phase mixture but also holds immense implications for the development of smart, wettability-based oil separation devices.

Harsh environmental-tolerant, superhydrophilic and underwater superoleophobic cellulose hydrogel-coated copper foam for efficient and repeatable oil/water separation

The increasingly serious situation of oil leakage makes it crucial to design a separation material that is convenient, green and durable to address the problem of oil-water mixture. In this...

THE EFFECT OF ATOMIZED SOYBEAN OIL EMULSIONS USED AS CUTTING FLUID ON THE CUTTING PERFORMANCE

Within the scope of sustainable production, a natural liquid mixture that will act as cutting fluid is sprayed with a different system. The liquid consisting of water and soybean oil was pulverized by ultrasonic atomization method and used by spraying with 4 bar compressed air. In this study, it was aimed to investigate the effects of AISI 4140 steel on machinability in CNC lathe by using uncoated carbide insert (SECO WNMG080404-M1). Three cutting speeds (150, 200, 250 m / min), three feed rates (0.1, 0.15, 0.2 mm / rev) with four cutting fluids (1%, 5%, 10% soy oil-water mixture and commercial cutting fluid) and the comparison was made by making experiments under dry cutting conditions. In all experiments, the cutting depth was 1 mm and the cutting length was 100 mm. As a result of the experiments, cutting force, surface roughness and tool wear values were examined and contact angle measurements of cutting fluids were made. The best results in all parameters were achieved by spraying a 10% soybean oil-water mixture using an ultrasonic atomizer. The best results in all parameters were achieved by spraying a 10% soybean oil-water mixture using an ultrasonic atomizer. The worst values occurred in experiments conducted under dry cutting condition. In addition, SEM photographs were taken to observe the type of tool wear. The obtained values were analyzed with the ANOVA method and the results were evaluated with 3D surface graphics. After evaluating the analysis results, percentage impact rates, regression analysis equations and optimization values are proposed.

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

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

The optimized microbial-induced calcium carbonate precipitation process to fabricate underwater superoleophobic mesh for efficient oil-water separation

Microbial-induced calcium carbonate precipitation (MICP) is an environmentally-friendly and easy operation technique for separating oil-water mixtures. However, the effect of environmental factors on the wettability and oil-water separation performance of MICP remains unclear. In this study, three primary factors including mineralization solution (MS) concentration, bacterial suspension (BS) concentration, and temperature were carefully investigated. Under these varying conditions, stainless steel meshes (SSM) were chosen as the substrates for the growth of CaCO3 precipitations. Experimental results demonstrate a strong dependence of the morphology and wettability of CaCO3 precipitations on these factors. Higher MS concentration and temperature contribute to enhanced hydrophilicity of CaCO3 coatings due to the increased surface roughness. The water flux of MICP-coated SSMs decreases with the increase of BS concentration, MS concentration, and temperature. The MICP-coated SSM obtained with MS concentration of 0.15 M, BS concentration of 0.1 × 108 cells/mL, and mineralization reaction at 25 ℃ for 24 hours demonstrated the optimal comprehensive performance, exhibiting underwater superoleophobicity with an underwater oil contact angle (UWOCA) exceeding 151°, an ultra-high oil intrusion pressure (> 3.0 kPa), ultrahigh flux (28,644 L m−2 h−1), and a preferable oil rejection rate (> 99.9%). Additionally, the as-prepared mesh exhibited superior anti-oil-fouling property and reusability, while concurrently demonstrating excellent chemical and thermal stability. This work contributes to advancing our knowledge of the influence of various environmental factors on the wetting characteristics of MICP and provides a feasible solution for the highly efficient and low-cost preparation of oil-water separation membranes based on the MICP process.

Fabrication and oil-water separation properties of cerium oxide coated zirconium oxide composite membranes

Traditional oil-water separation membranes have high preparation costs and easy environmental pollution during the manufacturing process, so the development of new oil-water separation membranes with low cost and high environmental value is an important topic. In this work, cerium oxide coated zirconium oxide (CeO2/ZrO2) composite membranes are fabricated on cotton fabric by a combination of physical and chemical methods, where CeO2 is prepared using Gossypium sppas a template. The experimental results show that the surface of the composite membrane forms a rough structure with multiple pore channels and the CeO2/ZrO2 composite membrane shows super-hydrophobicity (152.2°) and superlipophilicity. At the same time, the CeO2/ZrO2 composite membrane shows very high separation efficiency (98.26 %−99.53 %) for four oil-water mixtures. After the long-term stability test and cycling performance test, the CeO2/ZrO2 composite membrane shows good separation performance, and the flux of the membrane reaches 34411.9 Lm−2h−1. Meanwhile, the contact angle of the composite membrane is tested for acidic and alkaline environments, and the result shows that it has certain corrosion resistance. This provides an extended strategy to reduce environmental pollution and improve separation efficiency.

Sequestration of oils from water using superhydrophobic silanized montmorillonite-KSF nanoclay coated polyurethane foam

Oil spills have disastrous consequences on the environment. Multifarious absorbents have been applied in oil spill remediation; however, the design of cost-effective, dependable, and environmentally benign absorbents is desirable and pressing. Here, a polyurethane foam (PF) with superhydrophobic/superoleophilic properties was fabricated by surface coating of montmorillonite (MMT) nanoclay. Initially, the hydrophobic MMT was obtained by grafting octadecyltrimethoxysilane (ODTMS) onto the surface of the nanoclay and this was then used to modify the foam via a dip-coating technique. This modification produces a superhydrophobic foam with a water contact angle reaching 153.83 ± 1.86°. The as-prepared foam demonstrates high absorption selectivity and excellent absorption capacity of 29.5–66.5 times weight gain for several organic solvents and oils. The efficiency of separation for multiple oil-water mixtures reached 99.87%. After 10 cycles of absorption-desorption studies, such superhydrophobic foam still sustained good oil absorption performance, thus exhibiting outstanding reusability and desirable regeneration for practical applications. The oil and organic solvent samples could swiftly and continuously be retrieved from the water by the modified foam. The fabrication method for the superhydrophobic PF by its modification with natural clay minerals appears to be simple, economical, and promising for expandable applications in the effective separation of oil-water mixtures.

Bifunctional MOF‐5@coal‐based fiber membrane for oil-water separation and dye adsorption

Water pollution caused by oily and textile wastewater has become a global concerned problem. Wastewater typically contains organic dyes, oil-water emulsions and other pollutants. Hence, it is crucially important to prepare materials that can separate oil-water mixtures/emulsions and adsorb organic dyes. In this work, the semi-encapsulated MOF-5 modified coal-based fiber membranes were prepared by one-step electrospinning method. The modified membrane exhibits superhydrophilic/underwater superoleophobic, excellent stability, high flux (oil-water mixture flux = 8861 L m-2 h-1, oil-in-water emulsion flux = 504 L m-2 h-1) and commendable separation efficiency (98.7%, 99.9%). The membrane could achieve a highly efficient dye absorption (94.9%). The semi-encapsulated construction makes the MOF-5 well protected and the active site can be greatly exposed, leading to significantly improved stability and adsorptive properties. The MOF-5 modification renders the surfaces hydrophilic and increases the roughness which improves water flux and wettability. The composite material provides a new idea for the separation of oil-water mixtures/emulsions and the adsorption of organic dyes.

Serial-module with hydrophilic and hydrophobic membranes applied for oil recovery from O/W emulsion

Membrane demulsification has been extensively employed for separating various oil–water mixtures, however, the recovery oil droplets from highly emulsified O/W mixtures remains a challenge. Herein, we develop a serial-module comprising arranged hydrophilic and hydrophobic membranes to recover the oil phase from O/W emulsion. Firstly, hydrophobic ceramic membranes were prepared through silane modification and separation performance towards emulsion with oil–water ratio of 1:1 was evaluated for both original hydrophilic membranes and modified hydrophobic ones. Subsequent, the sclareol extraction emulsion was chosen as a representative object to investigate and explore the separation performance of preferred membranes under varying oil–water ratios and surfactant concentrations. Ultimately, the results shows that serial-module demonstrated remarkable capability to recover emulsified oil droplets from sclareol extraction emulsion with 10 vol% oil even under complex conditions with yeast addition. This innovative serial-module provides a novel approach for efficiently separating emulsified mixtures of oil and water.

Facile fabrication of expanded graphite/polydimethylsiloxane foams for oil–water separation

3D porous foams for oil–water separation via selective adsorption were obtained by incorporating expanded graphite (EG) granules into polydimethylsiloxane (PDMS) foams. The EG@PDMS6-t foam prepared with a PDMS:EG and NaCl:PDMS mass ratio of 6:1 and 8:1, respectively, possesses a high porosity of 80.3%, a water contact angle of 127.7°, and an oil contact angle close to 0°. The foam exhibits an impressive adsorption capacity towards light oil (hexane,6.28 g/g), heavy oil (trichloromethane, 13.33 g/g), and kitchen waste oil (4.51 g/g), being able to separate 100% of oils from an immiscible oil–water mixture and 39.0% of camellia oil and 45.3% of kitchen waste oil from oil-in-water emulsions via selective adsorption. The foams possess excellent elasticity and desirable reusability in oil–water separation and exhibit outstanding resistance to acidic and alkaline environments. EG accounts for 96.5% of the EG@PDMS6-t foam’s volume. SiO2@PDMS hydrophobic layer was constructed on the top of EG@PDMS6-t foams by a spraying technique to tailor-make 3D filters for oil–water gravity-driven separation. The P20s-S0.2-EG@PDMS6-t filter shows an excellent immiscible trichloromethane-water gravity-driven separation, with a trichloromethane permeate flux of 11,024 L/m2h, a water rejection time of 60 s, and a separation efficiency of 99.7%. The filters are highly robust to chemical corrosion and tape-peeling.