Highly efficient separation of surfactant stabilized water-in-oil emulsion based on surface energy gradient and flame retardancy

Long, Mengying; Peng, Shan; Deng, Wanshun; Miao, Xinrui; Wen, Ni; Zhou, Qiannan; Deng, Wenli

doi:10.1016/j.jcis.2018.02.061

Cited by 33 publications

(10 citation statements)

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“…Because of the dramatic increase in the production of oil/water mixtures generated by domestic and industrial practices, including food, steel, petroleum, manufacturing, and so forth, the efficient segregation of oil/water mixtures has become an urgent challenge for the researchers all over the world. − For example, numerous oil-spill incidents and the direct release of oily wastewater not only disrupt the ecosystem balance and threaten human health but also cause the waste of precious resources. , Moreover, in the transportation field, a microscopic extent of water in fuel oil can greatly increase the risk of engine failure, resulting in severe consequences. , Generally, there are two categories of oil/water mixtures: stratified oil/water and emulsified oil/water, including oil-in-water and water-in-oil emulsions . Stratified oil/water mixtures containing relatively large (>20 μm) dispersed droplets, which can naturally separate over time, are thermodynamically unstable, and the denser phase gradually settles down while the lighter phase floats to the top.…”

Section: Introductionmentioning

confidence: 99%

“…4,5 Moreover, in the transportation field, a microscopic extent of water in fuel oil can greatly increase the risk of engine failure, resulting in severe consequences. 6,7 Generally, there are two categories of oil/water mixtures: stratified oil/ water and emulsified oil/water, including oil-in-water and water-in-oil emulsions. 8 Stratified oil/water mixtures containing relatively large (>20 μm) dispersed droplets, which can naturally separate over time, are thermodynamically unstable, and the denser phase gradually settles down while the lighter phase floats to the top.…”

Section: Introductionmentioning

confidence: 99%

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Separation Mechanism and Construction of Surfaces with Special Wettability for Oil/Water Separation

Chen

Ding

Mahmood

et al. 2019

ACS Appl. Mater. Interfaces

528

224

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Oil leakage and the discharge of oil/water mixtures by domestic and industrial consumers have caused not only severe environmental pollution and a threat to all species in the ecosystem but also a huge waste of precious resources. Therefore, the separation of oil/water mixtures, especially stable emulsion, has become an urgent global issue. Recently, materials containing a special wettability feature for oil and water have drawn immense attention because of their potential applications for oil/water separation application. In this paper, we systematically summarize the fundamental theories, separation mechanism, design strategies, and recent developments in materials with special wettability for separating stratified and emulsified oil/water mixtures. The related wetting theories that unveil the physical underlying mechanism of the oil/water separation mechanism are proposed, and the practical design criteria for oil/water separation materials are provided. Guided by the fundamental design criteria, various porous materials with special wettability characteristics, including those which are superhydrophilic/underwater superoleophobic, superhydrophobic/superoleophilic, and superhydrophilic/in-air superoleophobic, are systemically analyzed. These superwetting materials are widely employed to separate oil/water mixtures: from stratified oil/water to emulsified ones. In addition, the materials that implement the demulsification of emulsified oil/water mixtures via the ingenious design of the multiscale surface morphology and construction of special wettability are also discussed. In each section, we introduce the design ideas, base materials, preparation methods, and representative works in detail. Finally, the conclusions and challenges for the oil/water separation research field are discussed in depth.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Separation Mechanism and Construction of Surfaces with Special Wettability for Oil/Water Separation

Chen

Ding

Mahmood

et al. 2019

ACS Appl. Mater. Interfaces

528

224

View full text Add to dashboard Cite

show abstract

“…Up to now, a variety of methods have been developed to fabricate superhydrophobic surfaces on wood-based materials, such as hydrothermal treatment [ 7 , 8 ], sol-gel method [ 9 , 10 ], dip or spray-coating [ 11 , 12 , 13 , 14 ], soft lithography [ 15 , 16 ], “paint + adhesive” method [ 17 , 18 ], and so on. Among “paint + adhesive” methods, PDMS as adhesive has been successfully used to fabricate various robust and durable superhydrophobic surfaces [ 19 , 20 , 21 ]. However, there are few studies on the fabrication of lignocellulose composites superhydrophobic coatings.…”

Section: Introductionmentioning

confidence: 99%

Facile Fabrication of a PDMS@Stearic Acid-Kaolin Coating on Lignocellulose Composites with Superhydrophobicity and Flame Retardancy

et al. 2018

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The disadvantages such as swelling after absorbing water and flammability restrict the widespread applications of lignocellulose composites (LC). Herein, a facile and effective method to fabricate superhydrophobic surfaces with flame retardancy on LC has been investigated by coating polydimethylsiloxane (PDMS) and stearic acid (STA) modified kaolin (KL) particles. The as-prepared coatings on the LC exhibited a good repellency to water (a contact angle = 156°). Owing to the excellent flame retardancy of kaolin particles, the LC coated with PDMS@STA-KL displayed a good flame retardancy during limiting oxygen index and cone calorimeter tests. After the coating treatment, the limiting oxygen index value of the LC increased to 41.0. Cone calorimetry results indicated that the ignition time of the LC coated with PDMS@STA-KL increased by 40 s compared with that of uncoated LC. Moreover, the peak heat release rate (PHRR) and the total heat release (THR) of LC coated with PDMS@STA-KL reduced by 18.7% and 19.2% compared with those of uncoated LC, respectively. This LC coating with improved water repellency and flame retardancy can be considered as a potential alternative to protect the lignocellulose composite.

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“…[1][2][3] Moreover, tiny amounts of water in fuel can condense on the metal surface of an engine to produce corrosion, which greatly shorten its service-lifetime and increase the risk of engine failure. [4][5][6] Therefore, separation of oil/water mixtures has drawn growing interests of scientists and engineers all over the world. Conventional treatment techniques including gravity separation, centrifuge, air-flotation and biodegradation, have been employed to separate stratified oil/water mixtures.…”

Section: Introductionmentioning

confidence: 99%

Underoil Superhydrophilic Metal Felt Fabricated by Modifying Ultrathin Fumed Silica Coatings for the Separation of Water-in-Oil Emulsions

Chen

et al. 2020

ACS Appl. Mater. Interfaces

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Although various superhydrophobic/superoleophilic porous materials have been developed and successfully applied to separate water-in-oil emulsions through sizesieving mechanism, the separation performance is restricted by their nanoscale pore size severely. In this study, the wettability of underoil water on fumed silica was experimentally observed and underlying mechanism was investigated by carrying out theoretical analysis and molecular dynamic (MD) simulations. Further, we present a novel, facile and inexpensive technique to fabricate underoil superhydrophilic metal felt with micro pores for separation of water-in-oil emulsions by using SiO2 nanoparticles (NPs) as building blocks. The as-prepared underoil superhydrophilic coating is closed-packed and ultrathin (the thickness is approximate hundreds of nanometers), as well as capable of being coated on metal felt with complex structures without blocking its pores. The as-prepared metal felt could adsorb water droplets directly from oil, which endowed it with the ability to separate both surfactant-free and surfactant-stabilized water-in-oil emulsions with high separation efficiency up to 99.7% even though its pore size is larger than that of the emulsified droplet. The filtration flux for separation of span 80-stabilized emulsion is up to ~4000 L • m −2 • h −1 . Its separation performance is better than most of the other traditional membranes and superwettable materials used for separation of water-in-oil emulsions. Moreover, the as-prepared metal felt retained outstanding separation performance even after 30 cycles of use, which demonstrated its excellent reusability and durability. Additionally, the distinctive wettability of underoil superhydrophilicity endued coated metal felt with superior anti-fouling properties towards crude oil. Overall, this study not only provides a new perspective on separating water-in-oil emulsion, but also gives a universal approach to develop special wettability materials.

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Highly efficient separation of surfactant stabilized water-in-oil emulsion based on surface energy gradient and flame retardancy

Cited by 33 publications

References 50 publications

Separation Mechanism and Construction of Surfaces with Special Wettability for Oil/Water Separation

Separation Mechanism and Construction of Surfaces with Special Wettability for Oil/Water Separation

Facile Fabrication of a PDMS@Stearic Acid-Kaolin Coating on Lignocellulose Composites with Superhydrophobicity and Flame Retardancy

Underoil Superhydrophilic Metal Felt Fabricated by Modifying Ultrathin Fumed Silica Coatings for the Separation of Water-in-Oil Emulsions

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