PHYSICS OF FLUIDS
·
2023
·Vol. 35
·期 3
·
IF 4.6
Rong Feng,He Limin,Lǚ Yuling,Lu Xiaolei
To investigate the force model and motion law of oil droplets in water near the wetted wall, oil droplets with R 1 = 0.29–0.62 mm and oil films with R 2 = 1–6 mm are solved numerically. In addition to buoyancy, flow resistance, and added mass force, the film-induced force triggered by the wetted wall constraint is also introduced into the force model. The drainage process is described using the Stokes–Reynolds equation, and the Young–Laplace equation is used to calculate the pressure within the water film. The results show that the force model can be coupled with the Stokes–Reynolds–Young–Laplace model equation to better describe the drainage dynamics near the wetted wall. The pressure distribution law is closely related to the shape of the water film, especially when the oil–water interface is in the shape of a dimple, which can lead to the formation of negative pressure zones within the water film. The maximum pressure first grows in an exponential, then logarithmic pattern and eventually approaches the equivalent Laplace pressure. Around the critical size, the direction of the film-induced force changes and the form of action switches between driving and drag forces. The film-induced force's dominant effect is strongest when the curvature radius of the oil film is comparable to the droplet size.
研究领域:
流体力学
·
界面化学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2018
·Vol. 28
·期 49
·1800775
·
IF 13.325
Yufeng Yan,Zhenyan Guo,Xiaofang Zhang,Linlin He,Yan Li,Kesong Liu,Jinhua Cai,Dongliang Tian,Lei Jiang
Directional motion of fluid droplets is attracting considerable research attention. Despite much progress in this field, electrowetting-based stiction switch that drives unidirectional transport of an underwater oil droplet or air bubble on a wire surface is still a challenge to realize. Here, a strategy to collect and unidirectionally transport an underwater oil droplet or air bubble on a porous polystyrene (PS) film-coated copper wire surface through the combination of electrowetting-induced stiction switch and buoyancy is demonstrated. The porous PS film-coated copper wire fabricated by the breath figure method at a relative humidity of 75% can catch and hold an underwater oil droplet or air bubble without applied voltage. With increasing applied voltage, the stiction of the underwater oil droplet or air bubble on the porous PS film surface weakens because water increasingly wets the film surface. The underwater oil droplet or air bubble can move unidirectionally on the porous PS film-coated wire surface upward or downward at a voltage larger than its critical voltage according to whether its density is lower or higher than that of water. This work should aid the development of devices displaying electrowetting-based changes for use in fluid collection, manipulation, unidirectional transfer, release, and removal.
研究领域:
材料科学
·
流体物理
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Yuling Lü,Ce Wang,Yulong Ma,Tianxu Ye,Limin He
The weak adhesion between oil droplets and bubbles frequently reduces the flotation effectiveness of oil removal. This study focuses on the hydrophobic and oleophilic modification of bubble surfaces by encapsulating light hydrocarbon homologue-condensate to address this issue. The adhesion properties were characterized by the surface properties and interaction barriers of oil droplets and air/ condensate bubbles. The results indicated that condensate bubbles exhibited shorter induction time and faster spreading rate than air bubbles when adhering to oil droplets. The condensate film effectively extracted the oil droplets and completely enveloped the bubble surface. Furthermore, the non-DLVO model best fitted bubble induction time, revealing negative interaction energy barriers that promoted adhesion between condensate bubbles and oil droplets. In summary, coating a condensate film on bubble surfaces enhances the adhesion effect on oil droplets, which research provides valuable theoretical guidance for applying condensate bubble flotation process.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Zhili Li,Junyi Chen,Yuanyuan Ge
Water contamination is one of the most serious problems afflicting people throughout the world, innovation of nanomaterials with eco-friendliness is important for a greener environment. Here, an eco-friendly nanocomposite based on lignin grafted carbon nanotubes (L-CNTs) is reported as a new type of adsorbent for water remediation. By integrating the tridimensional structure, oxygen-containing functional groups and eco-friendliness of lignin with the high surface area and mechanical stability of CNTs, the as-prepared nanocomposite not only possesses a good water-dispersibility and eco-friendliness, but also exhibits an excellent adsorption capability for lead ion and oil droplet. It shows a high distribution coefficient for lead ion ( K d = 3.6 × 10 5 mL/g) that is comparable to some benchmark materials, including mesoporous carbon and metal-organic frameworks. The large surface area and tridimensional structure also endows L-CNTs with a high removal efficiency for oil droplet from water. Moreover, the cost of the nanocomposite has been minimized by incorporation of the low cost lignin. These results demonstrate the as-obtained nanocomposite with a natural polymer layer has advanced adsorption capability, low-in cost and eco-friendliness, and accordingly is an ideal candidate for water cleanup.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
SURFACE REVIEW AND LETTERS
·
2019
·
IF 0.748
HYONCHOL CHOE,SONGHAK KIM,CHOLHUAN O,JISONG ZONG,WONCHOL SONG
In this study, the apparent contact angles of oil droplets on the rough surfaces in water were numerically studied using the Volume of Fluid (VOF) model. The results showed that the roughness of the surface affected the wettability. By increasing the roughness of the surface, the oleophilicity of the oleophilic surface and the oleophobicity of the oleophobic surface could be increased. Furthermore, the applicability and limitations of the prediction of the underwater apparent contact angle of the oil droplet by the contact angle model were investigated by 3D numerical simulations. It suggests that Wenzel model can accurately predict the underwater apparent contact angle of oil droplets on all the oleophilic, neutral and oleophobic surfaces, and Cassie model can only be applied to the oleophobic surface and Cassie–Baxter model can only be applied to the oleophilic surface.
研究领域:
材料科学
·
流体力学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2020
·
IF 3.557
Yunrui Han,Shipeng Wang,Lin Han,Limin He,Xiaoming Luo
In this aticle, the continuous movement patterns and characteristic parameters of oil droplets on surfaces with different wettability immersed in a laminar flow field were observed, and the change rules of the geometric parameters of oil droplets under different experimental conditions were obtained. Then, the factors influencing the continuous moving behaviors of the oil droplets were analyzed, and the continuous movement velocity of the oil droplets under different experimental conditions was demonstrated. On this basis, the change law of the continuous movement velocity of oil droplets with the flow velocity was discussed. In addition, the coupling effect of the oil drops’ height, surface properties, and water flow velocity on the continuous movement of oil droplets was studied, and the critical conditions for the continuous movement were obtained. According to the critical conditions, the mathematical model which described the law of continuous motion of the oil droplets adhered on surfaces with different wettability in the laminar flow field was established. The quantitative relationships among the average continuous moving velocity of oil droplets, physical properties, geometric parameters, water flow velocity, and surface wettability were obtained, which defined the necessary conditions for the uniform and accelerated movement of oil droplets, providing an important basis for choices of suitable surface wettability and flow field conditions in practical engineering applications.
研究领域:
物理学
·
工程学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2016
·Vol. 26
·期 44
·7986-7992
·
IF 11.382
Dongliang Tian,Linlin He,Na Zhang,Xi Zheng,Yuhai Dou,Xiaofang Zhang,Zhenyan Guo,Lei Jiang
Driving a liquid droplet with control of directional motion on a solid surface, by introducing a surface wettability gradient or external stimuli, has attracted considerable research attention. There still remain challenges, however, due to the slow response rate and slow speed of continuous liquid droplet motion on the structured surface. Here, an approach to continuously drive the underwater oil droplet with control of directional motion by the cooperative effects of an electric field and the gradient of a porous polystyrene microstructure is demonstrated. The gradient microstructure induces the liquid droplet to take on an asymmetrical shape, causing unbalanced pressure on both ends to orient the droplet for motion in a particular direction. Meanwhile, the electric field decreases the contact area and the corresponding viscous drag between the droplet and the gradient-structured surface. Then, the unbalanced pressure pushes the underwater oil droplet to move directionally and continuously at a certain voltage. This work provides a new strategy to control underwater oil droplets and realize unidirectional motion. It is also promising for the design of new smart interface materials for applications such as electrofluidic displays, biological cell and particle manipulation, and other types of microfluidic devices.
研究领域:
材料科学
·
微流体技术
·
界面化学
✓ 已验证
产品关联
DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 101
·期 7
·4170-4183
·
IF 2.5
Feng Rong,Limin He,Yuling Lü,Ce Wang,Shipeng Wang
Microscopic adhesion of oil droplets is a hot research topic within multiphase flow systems in the petrochemical field in recent years, and it is also the key to revealing the mechanism of oil droplet–wall interaction. In this paper, a high-speed camera was used to capture the dynamic process of oil droplets impacting stainless steel, polyethylene, brass, and other materials in water, deeply analyze the influence mechanism of material wettability, droplet size, and inclination on adhesion behaviour in this process, and draw the Re~ θ eq phase diagram. The experimental results show that properly enhancing the lipophilicity of the material can prolong the drainage time and effectively inhibit adhesion. Too much lipophilicity can dramatically shorten the drainage time instead, which easily leads to the rapid adhesion of oil droplets. An increase in droplet size can also prolong the drainage time; at Re ≥46.31, the excessive initial kinetic energy is consumed in the form of oil droplet rebound, which is not conducive to adhesion, and the more lipophilic the material is, the more significant the rebound effect. In addition, although an increase in the inclination can inhibit oil droplet bounce off, it also decreases the wall restraint to oil droplets, resulting in lateral and normal displacements, which greatly increases the drainage time. The findings can facilitate the understanding of oil droplet–wall interaction and provide a scientific basis for the design and development of efficient separation equipment and the optimization of the low-temperature gathering and transportation of high water-bearing crude oil.
研究领域:
石油工程
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Ming Li,Ming Xu,Lijuan Sun,Chunyun Zhu,Jincheng Liu,Qinshan Liu,Yaowen Xing,Xiahui Gui
The surface microbubbles (SMBs) induced by air nucleation on mineral surfaces exert a powerful influence over enhancing the adhesion of air bubbles or oil droplets on mineral surfaces in flotation . The contact angles and TPLs were characterized by captive-bubble/oil droplet on the graphite surfaces. They were combined with dynamic bubble/oil droplet-graphite surface attachment and detachment visualization and force measurements using a microbalance system equipped with a camera to demonstrate the role of SMBs in bubble/oil droplet-graphite surface adhesion. The results show that after depressurization, the dissolved air in water nucleates on both hydrophobic and oxidized graphite surfaces, resulting in SMBs formation, which can enhance the adhesion of bubbles/oil droplets with the different graphite surfaces. For bubble-solid adhesion, these enhancements are attributed to the bridging effect of the SMBs coalescing with the large bubble increasing three-phrase contact lines (TPLs) and with this the adhesion forces. For oil-solid interactions, SMBs induce the attachment and spreading of the oil droplet on the graphite surfaces, as the TPLs and spreading forces are increased. SMBs also result in a more stable oil droplet-graphite interface, as the adhesion forces are improved. Therefore, SMBs are efficient for improving graphite flotation by increasing the stability of the mineralized bubble and promoting the spreading and adhesion of dodecane oil. Hence, SMBs coupled with the modification of the surface hydrophobicity may be more beneficial for flotation separation.
研究领域:
矿物加工工程
·
界面科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2015
·
IF 2.752
Xiuying Qiao,Lijun Wang,Zhengzhong Shao,Kang Sun,Reinhard Miller
In this study, oil/water emulsions stabilized by natural silk fibroin were prepared, and the effects of silk fibroin concentration ( φ SF ), oil volume fraction ( ϕ o ) and oil type on the stability and rheological behavior investigated. After creaming and reaching a stable state, the residual emulsion fraction increases with an increase in φ SF , ϕ o and oil polarity, while the size of emulsion droplets decreases with an increase in φ SF and oil polarity but a decrease in ϕ o . Due to the colloidal networks formed by the dispersed oil droplets, the emulsions show a predominantly elastic behavior with a frequency independent modulus and low phase angle. However, the droplet networks are not very strong, and a remarkable shear-thinning behavior occurs for all emulsions during steady shear flow. Moreover, stress overshoot also appears for some emulsions with low φ SF and polar oil during transient shear flows, due to the deformation of droplets before the breakage of their associates. The modulus, viscosity and yield stress become larger with the increase of φ SF , ϕ o and oil polarity, which is very beneficial for strengthening the creaming stability of the emulsions.
研究领域:
食品科学
·
材料科学
·
界面化学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2022
·
IF 11.357
Xi Li,Huachun Lan,Gong Zhang,Xiao Tan,Huijuan Liu
Oily wastewater treatment has been restricted by the existence of stable oil-in-water (O/W) emulsions containing micrometer-sized oil droplets. However, the strong adhesion and stacking of emulsified oil droplets on the surface of current separation media cause serious fouling of the treatment unit and the rapid decline of treatment efficiency. Herein, a novel flow-through titanium (Ti) electrode-based filtration device with remarkable oil droplet rejection property was well designed for the continuously separating O/W emulsion. In contrast to the pristine Ti foam, the permeance of the TiO2 nanoarray-coated Ti foam (NATF) increased from 2538 to 4364 L m–2 h–1 bar–1 through gravity-driven flow. Further, more than ∼70% permeability can be maintained after 6 h of O/W emulsion filtration using the current device, the value of which was markedly higher than that of conventional oil/water separation filters (less than 5%). According to the results of wettability test, the super-oil-repellent surface endowed by this nanoarray structure primarily avoided the formation of a compact oil fouling layer. When the voltage was applied, accompanied by the electrophoresis effect, redistribution of surfactant molecules on the surface of oil droplets induced by an electric field made them readily captured by the microbubbles continuously generated from the electrode, thereby rapidly migrating these bubble-adhered oil droplets far from the filtration medium.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
Nature Communications
·
2019
·Vol. 10
·期 1
·1-8
·
IF 11.878
Wang Qianbin,Xu Bojie,Hao Qing,Wang Dong,Liu Huan,Jiang Lei
Materials with in situ reversible wettability have attractive properties but remain a challenge to use since the inverse process of liquid spreading is normally energetically unfavorable. Here, we propose a general electrochemical strategy that enables the in situ reversible superwetting transition between underwater superoleophilicity and superoleophobicity by constructing a binary textured surface. Taking the copper/tin system as an example, the surface energy of the copper electrode can be lowered significantly by electrodeposited tin, and be brought back to the initial high-energy state as a result of dissolving tin by removing the potential. Tin atoms with the water depletion layer inhibit the formation of a hydrogen-bonding network, causing oil droplets to spread over the surface, while copper atoms, with a high affinity for hydroxyl groups, facilitate replacing the oil layer with the aqueous electrolyte. The concept is applicable to other systems, such as copper/lead, copper/antimony, gold/tin, gold/lead and gold/antimony, for both polar and nonpolar oils, representing a potentially useful class of switchable surfaces.
研究领域:
材料科学
·
表面工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）