High Oil-water Separation Efficiency Research Articles

Designing novel superwetting surfaces for high-efficiency oil–water separation: design principles, opportunities, trends and challenges

The limitations of traditional separation technology force people to find a more advanced separation technology, while the special wetting material has attracted the attention of most researchers.

Engineering superhydrophobic-superoleophilic nylon mesh for high-efficiency oil-water separation

Engineering superhydrophobic-superoleophilic nylon mesh for high-efficiency oil-water separation

Fabrication of superhydrophobic marigold shape LDH films on stainless steel meshes via in-situ growth for enhanced anti-corrosion and high efficiency oil-water separation

A superhydrophobic marigold shape layered double hydroxide (LDH) film coated stainless steel mesh (SSM) was prepared by in-situ growth followed chemical modification in this work. The obtained SSM exhibited excellent superhydrophobicity, self-cleaning ability, physical and chemical durability, indicating the superior ability of adapting to outdoor environment. In addition, the obtained SSM also exhibited excellent corrosion resistance and the efficiency reached up to 97.3%. As for application evaluation, the obtained SSM could be applied in continuous oil-water separation with a high efficiency and flux after 50 times reuse (98.5% and 1800 L m−2 h−1 for chloroform-water mixture). More importantly, the obtained SSM exhibited a high intrusion pressure (5.39 kPa), which was helpful to the rapid separation of oil-water mixture. Consequently, the obtained superhydrophobic SSM offered a promise in solving practical application problems of oil-water separation in outdoor and thereby showed great potential in large-scale industrial applications.

Simple fabrication of superhydrophobic PLA with honeycomb-like structures for high-efficiency oil-water separation

Polylactic acid (PLA) is one of the most suitable candidates for environmental pollution treatment because of its biodegradability which will not cause secondary pollution to the environment after application. However, there is still a lack of a green and facile way to prepare PLA oil-water separation materials. In this work, a water-assisted thermally induced phase separation method for the preparation of superhydrophobic PLA oil-water separation material with honeycomb-like structures is reported. The PLA material shows great ability in application and could adsorb 27.3 times oil to its own weight. In addition, it could also be applicated as a filter with excellent efficiency (50.9m3m−2h-1).

Separation of oil-water emulsion and adsorption of Cu(II) on a chitosan-cellulose acetate-TiO2 based membrane

A modified cellulose acetate, modified chitosan, titanium dioxide membrane (MCA-MCS-TiO2) was prepared for oil-water emulsion separation and Cu(II) adsorption. This membrane shows excellent hydrophilicity and underwater oleophobicity. After being modified, the water contact angles of the membranes attain 13.7°, and the underwater oil contact angles reach 157.24°. The membrane exhibits high oil-water separation efficiency (99.4%) for cyclohexane, at the same time, the adsorption amount of Cu(II) on the membrane was measured. The variables include the ratio of modified cellulose to modified chitosan, the initial concentration of Cu(II), and the pH of Cu(II) solution. When pH = 7, the adsorption capacity of the membrane to Cu(II) reaches 220.67 mg g−1. When the concentration of Cu(II) solution is 1000 mg L−1, the adsorption efficiency is as high as 97.0%.

Ultra-high flux and efficient oil-water separation via polymer-based electrophoretic deposition

A highly efficient steel mesh-based coating for oil-water separation with ultra-high flux was fabricated by an electrophoretic deposition process using a crosslinked water-soluble silicon-containing polyacrylate (WSPA). Dichloromethane, n-hexane, and toluene passed through the modified steel mesh with flux above 100,000 L·m−2·h−1 solely driven by gravity, while the modified mesh also offered a very high oil-water separation efficiency of 99.5%. The separation efficiency of the prepared mesh remained above 99.0% after treatment in various harsh environments, including acidic (pH 0) and alkaline (pH 14) media as well as concentrated brine for 24 h. In particular, the modified mesh was suitable for the separation of viscous oils (such as crude oil and pump oil) from water with a separation efficiency of no less than 85.0% and a flux exceeding 500 L·m−2·h−1. This study provides a cost-efficient way to prepare environmentally-friendly coatings on stainless steel meshes without requiring toxic fluorinated compounds.

MXene-Coated Mesh Membrane with Underwater Superoleophobicity for High-efficiency Oil-water Separation†

MXene-Coated Mesh Membrane with Underwater Superoleophobicity for High-efficiency Oil-water Separation†

Electrospun frogspawn structured membrane for gravity-driven oil-water separation

The aim of this study is to prepare a fibrous membrane scaffold that possesses a frogspawn structure for high-efficiency oil-water separation. Polyamic acid was first electrospun onto a rotating wheel-collector to obtain the fibrous membrane. Subsequently, post-processing by immersion in a polydimethylsiloxane solution and a silica nanoparticles suspension, followed by a thermal treatment generated a frogspawn-structured fibrous membrane. The obtained membrane achieved superhydrophobicity and superoleophilicity, with the water contact angle as high as 155.75° and the oil contact angle lower than 10°. The separation efficiencies of the membrane were higher than 99.55% and the permeate flux was maintained at greater than 4400 L/m2∙h after 20 separation cycles. Additionally, the wettability studies suggested the membrane exhibits high stability because it can resist damages due to high temperature (150 °C), acid/basic conditions and organic/inorganic solvents. These findings indicated that this composite membrane has great potential for use in gravity-driven oil-water separation and can extend the range of its application for treatments of oil spills incident, oily wastewater and spent liquor.

Hydrophobically modified chitin/halloysite nanotubes composite sponges for high efficiency oil-water separation.

A high-performance oil-water separation device that built by environment-friendly materials is a promising strategy to solve water pollution problem. In this study, we developed an oil-water separation system with chitin/halloysite nanotubes (C/HNTs) composites. C/HNTs were crosslinked by epichlorohydrin and freeze-dried, then a porous sponge was formed. The C/HNTs sponge was modified to be hydrophobic via immersing into bromohexadecane ethanol solution. The surface structure, mechanical properties, microstructure, oil absorption and oil-water separation ability of the C/HNTs sponge were investigated. The addition of HNTs significantly increased the compressive strength of chitin sponge without influence on porous structure. IR spectra indicated the successful coating of bromohexadecane on the C/HNTs sponge surface, which enabled the hydrophobicity and lipophilicity of this construct. The inside construct of the C/HNTs sponges were full of interconnected pores, and the pore size ranged from 250 to 500 μm. The absorption capability for various oil and grease were measured, including methylbenzene, sunflower seed oil, carbon dichloride, n-hexane, chloroform and acetone. It is found that the total amount of chloroform absorbed by a C/HNTs sponge was ~11.23 times of the sponge's weight, and the absorption for hexane was ~3.94 times of the sponge's weight. The sponge also exhibited an excellent oil-water separation ability with as high as 98.7% separation efficiency. All the results suggested that the chitin/HNTs sponges with improved mechanical property would have a great potential in oil-water separation.

Robust and self-healing superhydrophobic cotton fabric via UV induced click chemistry for oil/water separation

It is often difficult to guarantee the service life of fabric-based superhydrophobic materials that possess self-cleaning and oil–water separation capabilities. To extend practical use, a robust, self-healing superhydrophobic and superoleophilic cotton fabric was successfully prepared by simple impregnation and UV irradiation. The obtained superhydrophobic cotton had a contact angle of 152.4°. The as-prepared fabric showed excellent stability and remained superhydrophobic when soaked in corrosive liquids. Moreover, the prepared fabric can be used as an absorbent to separate the small amount of oil from the oil–water mixture and could be an oil/water separator by a simple device with the separation efficiency over 96%. More importantly, after 200 cycles of severe abrasion, the as-prepared fabric can retain superhydrophobicity and exhibit excellent self-healing property by simple heating treatment. With high oil–water separation efficiency and strong stability, the fabric prepared by this environmental-friendly method may contribute to the development of durable superhydrophobic materials.

Fabrication of stable superhydrophobic coating on fabric with mechanical durability, UV resistance and high oil-water separation efficiency

A durable and stable polydimethylsiloxane (PDMS) - copper stearate (CuSA2) superhydrophobic coating has been fabricated on cotton fabric by a simple in-situ growth and dip-coating method. The surface morphology, roughness and composition of the superhydrophobic coating were analyzed by SEM, 3D optical profiler and FT-IR, respectively. The prepared cotton fabric (C-fabric) showed good superhydrophobicity (WCA ~ 158°) and a satisfactory chemical stability against strong acidic/alkali solution and various solvents. The C-fabric retained superhydrophobicity with WCA above 150° after 24 h ultraviolet (UV) irradiation, 10 times of mechanical abrasion and 12 h ultra-sonication treatment. The obtained C-fabric also possessed anti-fouling property for various common household liquids (coke, juice, tea, ink, coffee and milk) with CA above 144°. Furthermore, the C-fabric can be applied to the separation of oil/water mixture with separation efficiency of more than 96%.

PDA-assisted one-pot fabrication of bioinspired filter paper for oil–water separation

Inspired by the robust and durable adhesion of mussels, highly hydrophobic filter paper was fabricated by a polydopamine (PDA)-assisted one-pot procedure using silica nanoparticles and silane coupling agent (hexadecyltrimethoxysilane, HDTMS) as coating materials at ambient temperature. The surface chemistry, morphology, and hydrophobicity of the coated filter paper were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscopy, and water contact angle. The capacity, durability, and recyclability of the coated filter paper were evaluated by the separation of oil–water mixtures and emulsions. The coated filter paper is highly hydrophobic with a water contact angle of > 130°. The coatings with enhanced adhesion to the substrate resisted mechanical abrasion without significant loss of hydrophobicity, which suggested that PDA plays a crucial role in improving the adhesion of silica nanoparticles to the paper surface. The coated filter paper showed high oil–water separation efficiency up to 95%, and maintained high hydrophobicity after recycling over 10 cycles. The coated filter paper that is based on a simple, low cost, and environmentally friendly procedure exhibits potential for applications in oil-recovery and oil–water separation materials.

A stable ZIF-8-coated mesh membrane with micro-/nano architectures produced by a facile fabrication method for high-efficiency oil-water separation

With the possibility of large-area processing, the ZIF-8-coated mesh membranes with rough micro-/nanostructures and underwater superoleophobic properties were successfully fabricated at ambient temperature and pressure. These membranes exhibited excellent separation efficiency over 99.99% for various oil-water mixtures with the residual oil content in the collected water less than 4 ppm, and high water flux of 10.2×104 L m−2 h−1. Furthermore, the ZIF-8-coated mesh membrane displayed outstanding stability towards high temperature and various organic solvents immersion. More importantly, based on its facile fabrication method, this kind of ZIF-8-coated mesh membrane can be easily enlarged, which is critical for the practical oil-water separation applications.

Construction of ZnO@Co3O4-loaded nickel foam with abrasion resistance and chemical stability for oil/water separation

In this work, superhydrophobic and superoleophilic nickel foam loaded with ZnO@Co3O4 hierarchical structure was successfully fabricated via a simplified one-pot hydrothermal method, followed by a brief calcination process and, finally, superhydrophobically modification with hexadecyltrimethoxysilan (HDTMS). The as-prepared nickel foam showed excellent abrasion resistance, chemical stability and high oil-water separation efficiency. The chemical composition and morphologies were characterized by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The sample we have manufactured proves to be a potential material for the separation of oil-water mixtures.

Ag nanoparticles loading of polypyrrole-coated superwetting mesh for on-demand separation of oil-water mixtures and catalytic reduction of aromatic dyes

Herein, a catalytic mesh with unique wettability, high oil-water separation efficiency and excellent catalytic performance towards aromatic dyes was fabricated. Polypyrrole (PPy) was firstly pre-coated on pristine stainless-steel mesh (SSM) surface via cyclic voltammetry approach. Subsequently, a simple electrodeposition process was performed to prepare and anchor Ag nanoparticles (AgNPs) onto the PPy-coated SSM surface. The PPy-coated mesh with anchored AgNPs was denoted as PPy/AgNPs-coated SSM. The obtained PPy/AgNPs-coated SSM exhibited dual superlyophobic properties and were able to achieve on-demand separation to deal with various of light oil (ρoil < ρwater) and heavy oil (ρoil > ρwater)-water mixtures. Importantly, benefitting from AgNPs on mesh surface, the obtained PPy/AgNPs-coated SSM exhibits exceptional catalytic activity. As proof-of-concept three typical aromatic dye molecules (methylene blue, rhodamine B and Congo red) can be effectivity degraded. Additionally, the degradation of aromatic dyes and oil-water separation were achieved simultaneously when the PPy/AgNPs-coated SSM was converted to water-removing mode. Therefore, the present work is of great significance to the development of novel oil-water filtration membranes and can open a new avenue towards the practicability of metal nanoparticle catalysts in wastewater treatment.

A durable and high-flux composite coating nylon membrane for oil-water separation

Abstract A durable and high-flux superhydrophilic-underwater superoleophobic oil-water separation membrane was prepared for effective oil-water separation by cellulose-starch-silica surface charging and hydrophilization. The surface properties of the composite coating nylon membrane were characterized by contact angle and scanning electron microscopy. The chemical structures of this membrane were confirmed by Fourier transform infrared spectroscopy and energy dispersive X-ray spectrometer. This membrane showed excellent hydrophilicity and underwater oleophobicity. After modified, the water contact angle of the membrane attained 0, and the underwater oil contact angles reached 159.5. The cellulose-starch-silica composite coating nylon membrane exhibited high oil-water separation efficiency (99.8%) for hexane, and it was also efficient for cyclohexane, petroleum ether, diesel, soybean oil, lubricating oil and silicone oil. Besides, the membrane flux could reach 31847 L−1m−2 h−1 bar−1. It showed this membrane had a high efficiency for oil-water separation. The modified nylon membrane was durable for oil-water separation. The separation efficiency could still retained above 97% after 100 cycles, and the modified nylon membrane still worked well after 24 h in harsh environment (pH value 4 to 10). The whole separation process could be achieved successfully without depending on any extra power. This work provided a new strategy to fabricate superhydrophilic and underwater superoleophobic membrane with good reusability, high flux and stability for oil-water separation.

UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil-Water Separation.

A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil-water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 104 L m-2 h-1, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil-water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification.

Facile one-pot synthesis of superhydrophobic reduced graphene oxide-coated polyurethane sponge at the presence of ethanol for oil-water separation

Polyurethane (PU) sponge has attracted significant interest in oil-water separation for its unique three-dimensional porous structure. However, its oil-absorption efficacy is dramatically limited by its poor hydrophobicity. Herein, superhydrophobic reduced graphene oxide-coated polyurethane (RGO@PU) sponge has been facilely fabricated using a one-pot solvothermal method at the presence of ethanol. The formation of RGO-coating layer on the surface of PU sponge is promoted with the assistance of ethanol, because the addition of ethanol decreases the surface tension of aqueous GO solution and improves the wettability of PU sponges. The as-prepared RGO@PU sponge with a superhydrophobic surface (water contact angle of 153°) exhibits a high oil-absorption capacity of more than 37 times of its original mass. A strong recycling absorption capacity (34 g/g) can be observed even after the RGO@PU sponge has experienced 50 oil absorption-desorption cycles. Moreover, our RGO@PU sponges have potential application as a promising absorbent for oil-water separation due to their fast oil-absorption rate (the oil can be removed in 5 s) and high oil-water separation efficiency (∼99%).

Design and preparation of efficient, stable and superhydrophobic copper foam membrane for selective oil absorption and consecutive oil–water separation

It is extremely important and challenging to develop an effective device for the continuous separation and recovery of large-scale oil–water mixtures due to their contribution to ecological remediation and contamination control. In this work, a superhydrophobic copper foam with high oil–water separation efficiency was successfully fabricated, which could serve both as oil absorption material and oil–water separation membrane, by in situ self-sacrificial template method combining the subsequent steaming modification. The obtained characterization results present that copper foam possesses large pore structure, micro-/nanoscale two-tier surface roughness, high water contact angle (153.6°), and low sliding angle (4.5°). Experimental results show that as-prepared copper foam could not only rapidly absorb residual oil either on the water surface or underwater, but also separate a series of oils from water, like carbon tetrachloride, trichloromethane, methylbenzene, pump oil and diesel. Furthermore, the separation efficiencies of copper foam on trichloromethane-water and diesel-water mixture were maintained above 96.9% and 90.8% after 10 cycles, respectively. Additionally, as-prepared copper foam exhibits excellent corrosion resistant ability and superior hydrophobic stability. The facile, low-cost and controllable strategy presented herein has a bright future in oil–water separation, and also can be further expanded to prepare various anti-corrosion, self-cleaning and water-proof sport materials.

An easy preparation of photo-response TiO2@copper wire mesh with quick on/off switchable superwetting for high efficiency oil–water separation

A photo-response superwetting was easily fabricated using a hydrothermal method and titanium dioxide (TiO2) on a copper wire mesh (CWM).