1
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Li D, Wang H, Manica R, Zhang Z, Zhang H, Liu Q. Quantifying Contributions of Different Repulsion to Film Drainage Time during the Bubble-Solid Surface Attachment and Implications for the Flotation of Fine Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10281-10292. [PMID: 38687814 DOI: 10.1021/acs.langmuir.4c00839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The flotation recovery of fine particles faces serious challenges due to the lack of kinetic energy required for supporting their radial displacement and attachment with bubbles. Generally, the hydrodynamic resistance and repulsive disjoining pressure successively inhibit the liquid outflow intervening between the bubble and solid surfaces. To quantitatively characterize the influence of the main repulsion on film thinning time, experiments have been designed in three different aqueous systems. Bubble surface mobility closely associated with hydrodynamic resistance was determined by the rising bubble technique, and the DLVO theory was employed to confirm the evolution of electrostatic repulsion. The film drainage process was then measured based on the high-speed microscopic interferometry. Furthermore, the influence of the main repulsion on bubble-solid surface interactions was examined by flotation recovery. Results show that the earlier buildup of hydrodynamic force ran through the whole film thinning process, and under immobile conditions, the central region gradually became dominant in film thinning due to the very limited fluid flow at the thinnest rim position. Therefore, to achieve the identical film thickness (∼100 nm), the large hydrodynamic resistance could prolong the film thinning time by about 1 order of magnitude, compared with that induced by electrostatic repulsion, which accounts for the increased flotation recovery by 10% using mobile bubbles. This study not only enhances the understanding of how typical repulsive forces work in film drainage dynamics but also opens up an avenue for enhancing flotation and avoiding wasting resources by modulating bubble surface mobility and thus micro/nanoscale fluid flow.
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Affiliation(s)
- Danlong Li
- School of Chemical Engineering and Technology, China University of Mining and Technology, 221116 Xuzhou, China
- Future Technology School, Shenzhen Technology University, Shenzhen 518118, China
| | - Hainan Wang
- School of Chemical Engineering and Technology, China University of Mining and Technology, 221116 Xuzhou, China
| | - Rogerio Manica
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Zhaokun Zhang
- School of Chemical Engineering and Technology, China University of Mining and Technology, 221116 Xuzhou, China
| | - Haijun Zhang
- School of Chemical Engineering and Technology, China University of Mining and Technology, 221116 Xuzhou, China
| | - Qingxia Liu
- School of Chemical Engineering and Technology, China University of Mining and Technology, 221116 Xuzhou, China
- Future Technology School, Shenzhen Technology University, Shenzhen 518118, China
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
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2
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Guo H, Liu Q, Huang L, Liu J, Bao X, Zhang F, Cao Y, Gui X, Xing Y, Xu M. Microfluidic Investigation of the Ion-Specific Effect on Bubble Coalescence in Salt Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37262019 DOI: 10.1021/acs.langmuir.3c00713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A microfluidic method was developed to study the ion-specific effect on bubble coalescence in salt solutions. Compared with other reported methods, microfluidics provides a more direct and accurate means of measuring bubble coalescence in salt solutions. We analyzed the coalescence time and approach velocity between bubbles and used simulation to investigate the pressure evolution during the coalescence process. The coalescence time of the three salt solutions decreased initially and then increased as the concentration of the salt solution was increased. The concentration with the shortest coalescence time is considered as the transition concentration (TC) and exhibits ion-specific. At the TC, the change in coalescence time indicates a shift in the effect of salt on bubble coalescence from facilitation to initial inhibition. Meanwhile, it can be seen that the sodium halide solutions significantly inhibit the bubble coalescence and the inhibition capability follows the order NaCl > NaBr > NaI. The results of the approach velocity show that the coalescence time decreases with increasing approach velocity, as well as the approach velocity was strongly influenced by concentration. The approach velocity undergoes a significant change at the TC. Furthermore, simulations of bubble coalescence in the microchannel indicate that the vertical pressure gradient at the center point of the bubble pairs increases as bubbles approach, driving liquid film drainage until bubble coalescence. The pressure at the center of the bubble pair reaches the maximum when the bubbles have first coalesced. It was further revealed that the concentration of the salt solution has a significant impact on the maximum pressure, as evidenced by the observed trend of decreasing pressure values with increasing concentrations.
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Affiliation(s)
- Han Guo
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Qinshan Liu
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Lulu Huang
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Jincheng Liu
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Xicheng Bao
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - FanFan Zhang
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Yijun Cao
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
- Henan Province Industrial Technology Research Institute of Resources and Materials, Zhengzhou University, Zhengzhou 450001, China
| | - Xiahui Gui
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Yaowen Xing
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Mengdi Xu
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
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3
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Dong H, Moyle N, Wu H, Khripin CY, Hui CY, Jagota A. The transition from Elasto-Hydrodynamic to Mixed Regimes in Lubricated Friction of Soft Solid Surfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211044. [PMID: 36779906 DOI: 10.1002/adma.202211044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 01/29/2023] [Indexed: 05/17/2023]
Abstract
Lubricated contacts in soft materials are common in various engineering and natural settings, such as tires, haptic applications, contact lenses, and the fabrication of soft electronic devices. Two major regimes are elasto-hydrodynamic lubrication (EHL), in which solid surfaces are fully separated by a fluid film, and mixed lubrication (ML), in which there is partial solid-to-solid contact. The transition between these regimes governs the minimum sliding friction achievable and is thus very important. Generally, the transition from EHL to ML regimes is believed to occur when the thickness of the lubricant layer is comparable with the amplitude of surface roughness. Here, it is reported that in lubricated sliding experiments on smooth, soft, poly(dimethylsiloxane) substrates, the transition can occur when the thickness of the liquid layer is much larger than the height of the asperities. Direct visualization of the "contact" region shows that the transition corresponds to the formation of wave-like surface wrinkles at the leading contact edge and associated instabilities at the trailing contact edge, which are believed to trigger the transition to the mixed regime. These results change the understanding of what governs the important EHL-ML transition in the lubricated sliding of soft solids.
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Affiliation(s)
- Hao Dong
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, 18015, USA
| | - Nichole Moyle
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, 18015, USA
| | - Haibin Wu
- Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | | | - Chung-Yuen Hui
- Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Anand Jagota
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, 18015, USA
- Department of Bioengineering, Lehigh University, Bethlehem, PA, 18015, USA
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4
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Niu H, Wang W, Dou Z, Chen X, Chen X, Chen H, Fu X. Multiscale combined techniques for evaluating emulsion stability: A critical review. Adv Colloid Interface Sci 2023; 311:102813. [PMID: 36403408 DOI: 10.1016/j.cis.2022.102813] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/09/2022] [Accepted: 11/10/2022] [Indexed: 11/17/2022]
Abstract
Emulsions are multiscale and thermodynamically unstable systems which will undergo various unstable processes over time. The behavior of emulsifier molecules at the oil-water interface and the properties of the interfacial film are very important to the stability of the emulsion. In this paper, we mainly discussed the instability phenomena and mechanisms of emulsions, the effects of interfacial films on the long-term stability of emulsions and summarized a set of systematic multiscale combined methods for studying emulsion stability, including droplet size and distribution, zeta-potential, the continuous phase viscosity, adsorption mass and thickness of the interfacial film, interfacial dilatational rheology, interfacial shear rheology, particle tracking microrheology, visualization technologies of the interfacial film, molecular dynamics simulation and the quantitative evaluation methods of emulsion stability. This review provides the latest research progress and a set of systematic multiscale combined techniques and methods for researchers who are committed to the study of oil-water interface and emulsion stability. In addition, this review has important guiding significances for designing and customizing interfacial films with different properties, so as to obtain emulsion-based delivery systems with varying stability, oil digestibility and bioactive substance utilization.
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Affiliation(s)
- Hui Niu
- Hainan University-HSF/LWL Collaborative Innovation Laboratory, School of Food Science and Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; SCUT-Zhuhai Institute of Modern Industrial Innovation, School of Food Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640, PR China
| | - Wenduo Wang
- School of Food Science and Technology, Guangdong Ocean University, Yangjiang 529500, Guangdong, PR China
| | - Zuman Dou
- Microbiome Medicine Center, Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, PR China
| | - Xianwei Chen
- SCUT-Zhuhai Institute of Modern Industrial Innovation, School of Food Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640, PR China
| | - Xianxiang Chen
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, PR China
| | - Haiming Chen
- Hainan University-HSF/LWL Collaborative Innovation Laboratory, School of Food Science and Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Maritime Academy, Hainan Vocational University of Science and Technology, 18 Qiongshan Road, Haikou 571126, PR China.
| | - Xiong Fu
- SCUT-Zhuhai Institute of Modern Industrial Innovation, School of Food Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640, PR China; Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Guangzhou 510640, PR China; Overseas Expertise Introduction Center for Discipline Innovation of Food Nutrition and Human Health (111 Center), Guangzhou, PR China.
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5
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Vakarelski IU, Langley KR, Yang F, Thoroddsen ST. Interferometry and Simulation of the Thin Liquid Film between a Free-Rising Bubble and a Glass Substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2363-2371. [PMID: 35129986 PMCID: PMC8867726 DOI: 10.1021/acs.langmuir.1c03374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/21/2022] [Indexed: 06/14/2023]
Abstract
Because of their practical importance and complex underlying physics, the thin liquid films formed between colliding bubbles or droplets have long been the subject of experimental investigations and theoretical modeling. Here, we examine the possibility of accurately predicting the dynamics of the thin liquid film drainage using numerical simulations when compared to an experimental investigation of millimetric bubbles free-rising in pure water and colliding with a flat glass interface. A high-speed camera is used to track the bubble bounce trajectory, and a second high-speed camera together with a pulsed laser is used for interferometric determination of the shape and evolution of the thin liquid film profile during the bounce. The numerical simulations are conducted with the open source Gerris flow solver. The simulation reliability was first confirmed by comparison with the experimental bubble bounce trajectory and bubble shape evolution during the bounce. We further demonstrate that the simulation predicted time evolution for the shape of the thin liquid film profiles is in excellent agreement with the high-speed interferometry measured profiles for the entire experimentally accessible film size range. Finally, we discuss the implications of using numerical simulation together with theoretical modeling for resolving the complex processes of high velocity bubble and droplet collisions.
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Affiliation(s)
- Ivan U. Vakarelski
- Division
of Physical Sciences and Engineering, King
Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Kenneth R. Langley
- Division
of Physical Sciences and Engineering, King
Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Department
of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee Space Institute, Tullahoma, Tennessee 37388, United States
| | - Fan Yang
- Division
of Physical Sciences and Engineering, King
Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Sigurdur T. Thoroddsen
- Division
of Physical Sciences and Engineering, King
Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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6
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Thin liquid films: Where hydrodynamics, capillarity, surface stresses and intermolecular forces meet. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101441] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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7
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Shang C, Fan F. Preparation of ionogel-bonded mesoporous silica and its application in liquid chromatography. NEW J CHEM 2021. [DOI: 10.1039/d1nj03244e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A new preparation strategy for stable ionogels on silica obtained by a chemical bonding method and its application in LC.
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Affiliation(s)
- Ce Shang
- E&D Research Institute of Liaohe Oilfield Company, Panjin, 124010, China
| | - Fangbin Fan
- Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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8
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Liu B, Manica R, Xu Z, Liu Q. The boundary condition at the air–liquid interface and its effect on film drainage between colliding bubbles. Curr Opin Colloid Interface Sci 2020. [DOI: 10.1016/j.cocis.2020.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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9
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Chatzigiannakis E, Veenstra P, Ten Bosch D, Vermant J. Mimicking coalescence using a pressure-controlled dynamic thin film balance. SOFT MATTER 2020; 16:9410-9422. [PMID: 32785335 DOI: 10.1039/d0sm00784f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The dynamics of thin films containing polymer solutions are studied with a pressure-controlled thin film balance. The setup allows the control of both the magnitude and the sign as well as the duration of the pressure drop across the film. The process of coalescence can be thus studied by mimicking the evolution of pressure during the approach and separation of two bubbles. The drainage dynamics, shape evolution and stability of the films were found to depend non-trivially on the magnitude and the duration of the applied pressure. Film dynamics during the application of the negative pressure step are controlled by an interplay between capillarity and hydrodynamics. A negative hydrodynamic pressure gradient promoted the thickening of the film, while the time-dependent deformation of the Plateau border surrounding it caused its local thinning. Distinct regimes in film break-up were thus observed depending on which of these two effects prevailed. Our study provides new insight into the behaviour of films during bubble separation, allows the determination of the optimum conditions for the occurrence of coalescence, and facilitates the improvement of population balance models.
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Affiliation(s)
| | - Peter Veenstra
- Shell Global Solutions International B.V., 38000 Amsterdam, The Netherlands
| | - Dick Ten Bosch
- Shell Global Solutions International B.V., 38000 Amsterdam, The Netherlands
| | - Jan Vermant
- Department of Materials, ETH Zürich, 8032 Zürich, Switzerland.
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10
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Chatzigiannakis E, Vermant J. Breakup of Thin Liquid Films: From Stochastic to Deterministic. PHYSICAL REVIEW LETTERS 2020; 125:158001. [PMID: 33095612 DOI: 10.1103/physrevlett.125.158001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
The thinning and rupture of thin liquid films is a ubiquitous process, controlling the lifetime of bubbles, antibubbles, and droplets. A better understanding of rupture is important for controlling and modeling the stability of multiphase products. Yet literature reports that film breakup can be either stochastic or deterministic. Here, we employ a modified thin film balance to vary the ratio of hydrodynamic to capillary stresses and its role on the dynamics of thin liquid films of polymer solutions with adequate viscosities. Varying the pressure drop across planar films allows us to control the ratio of the two competing timescales, i.e., a controlled hydrodynamic drainage time and a timescale related to fluctuations. The thickness fluctuations are visualized and quantified, and their characteristics are for the first time directly measured experimentally for varying strengths of the flow inside the film. We show how the criteria for rupture depend on the hydrodynamic conditions, changing from stochastic to deterministic as the hydrodynamic forces inside the film damp the fluctuations.
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Affiliation(s)
| | - Jan Vermant
- Department of Materials, ETH Zürich, Vladimir Prelog Weg 5, 8032 Zürich, Switzerland
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11
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Camacho RM, Fish D, Simmons M, Awerkamp P, Anderson R, Carlson S, Laney J, Viglione M, Nordin GP. Self-Sustaining 3D Thin Liquid Films in Ambient Environments. ADVANCED MATERIALS INTERFACES 2020; 7:1901887. [PMID: 33072494 PMCID: PMC7566691 DOI: 10.1002/admi.201901887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Indexed: 06/11/2023]
Abstract
Thin liquid films (TLF) have fundamental and technological importance ranging from the thermodynamics of cell membranes to the safety of light-water cooled nuclear reactors. The creation of stable water TLFs, however, is very difficult. In this paper, the realization of thin liquid films of water with custom 3D geometries that persist indefinitely in ambient environments is reported. The wetting films are generated using microscale "mounts" fed by microfluidic channels with small feature sizes and large aspect ratios. These devices are fabricated with a custom 3D printer and resin, which were developed to print high resolution microfluidic geometries as detailed in Reference 26. By modifying the 3D-printed polymer to be hydrophilic and taking advantage of well-known wetting principles and capillary effects, self-sustaining microscale "water fountains" are constructed that continuously replenish water lost to evaporation while relying on surface tension to stabilize their shape. To the authors' knowledge, this is the first demonstration of stable sub-micron thin liquid films (TLFs) of pure water on curved 3D geometries.
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Affiliation(s)
- Ryan M Camacho
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Davin Fish
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Matthew Simmons
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Parker Awerkamp
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Rebecca Anderson
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Stephanie Carlson
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Joshua Laney
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Matthew Viglione
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
| | - Gregory P Nordin
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84604, USA
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12
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Zawala J, Malysa K, Kowalczuk PB. On importance of external conditions and properties of the interacting phases in formation and stability of symmetrical and unsymmetrical liquid films. Adv Colloid Interface Sci 2020; 276:102085. [PMID: 31887573 DOI: 10.1016/j.cis.2019.102085] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 11/30/2022]
Abstract
Importance of external conditions and properties of phases creating liquid films, in outcome of the air bubble collisions with liquid/air and liquid/solids interfaces in clean water and in liquid solutions, is critically reviewed. The review is focussed on initial stages of the liquid films formation by bubbles colliding with interfaces, as well as, on analysis of the most important factors responsible for the collision's outcome, that is, either the rapid bubble bouncing or formation of the symmetrical or unsymmetrical liquid films and their thinning to the critical rupture thicknesses. Data on formation of liquid films under dynamic conditions, both in pure liquids and solutions of electrolytes and various surface-active substances, are reviewed and importance of hydrodynamic boundary conditions at interacting interfaces for energy balance in the system is discussed. It is shown that the liquid films stability, which in stagnant systems are directly determined by properties of the liquid/gas and liquid/solid interfaces, can be quite different in dynamic environment. A mechanism of the bubble bouncing from various interfaces in terms of interplay between energy exchange and kinetics of liquid film drainage is analyzed. It is shown that this mechanism is universal and irrelevant on the nature of interacting phases. Moreover, mechanisms responsible for wetting (unsymmetrical) film stability under dynamic conditions are discussed in light of the most recent studies, showing a crucial role of electrolyte, kind and concentration of surface-active substances, electrical surface charge, hydrophilic/hydrophobic properties of solids and presence of air entrapped (nano- and/or micro-bubbles) at surfaces of highly hydrophobic solids in the liquid films rupture.
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Affiliation(s)
- Jan Zawala
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland.
| | - Kazimierz Malysa
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Krakow, Poland
| | - Przemyslaw B Kowalczuk
- Norwegian University of Science and Technology, Department of Geoscience and Petroleum, S. P. Andersens veg 15a, 7031 Trondheim, Norway
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13
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Recent advances in studies of bubble-solid interactions and wetting film stability. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Xing Y, Xu M, Gui X, Cao Y, Rudolph M, Butt HJ, Kappl M. The role of surface forces in mineral flotation. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Gao Y, Jung S, Pan L. Interaction Forces between Water Droplets and Solid Surfaces across Air Films. ACS OMEGA 2019; 4:16674-16682. [PMID: 31616850 PMCID: PMC6788057 DOI: 10.1021/acsomega.9b02646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
Wetting of solid surfaces occurs when the intervening air film between a water droplet and a solid surface ruptures. Although this rupturing phenomenon is well known, the underlying mechanism has not yet been well understood. In this work, the rupture of intervening air films is systematically studied by measuring the spatiotemporal thickness profiles of the air films between droplets of deionized water and flat solid surfaces using a synchronized triwavelength reflection interferometry microscope. It has been shown that the critical rupture thickness of the air film (h c) depends on the surface hydrophobicity of solid surfaces. The h c value was increased from 50 nm on a hydrophobic surface having an equilibrium water contact angle (θw) of 96° to 1.42 μm on a hydrophilic surface having a θw of 25°. In addition, an increase in the critical rupture thickness with decreasing surface hydrophobicity was found to be applicable not only to chemically treated quartz surfaces but also to a variety of natural mineral surfaces. By determining the pressure within the air films, we have shown that a strong attractive force is present between water droplets and hydrophilic surfaces, thereby accelerating the draining of air films. The measured forces might be of electrostatic origin, and the forces become less attractive with increasing hydrophobicity of solid surfaces. The present result provides a fundamental insight into the rupture of air films from the perspective of surface forces.
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Affiliation(s)
- Yuesheng Gao
- Department
of Chemical Engineering, Michigan Technological
University, Houghton 49931, United States
| | - Sunghwan Jung
- Department
of Biological and Environmental Engineering, Cornell University, Ithaca 14853, United States
| | - Lei Pan
- Department
of Chemical Engineering, Michigan Technological
University, Houghton 49931, United States
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16
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Liu B, Manica R, Liu Q, Klaseboer E, Xu Z, Xie G. Coalescence of Bubbles with Mobile Interfaces in Water. PHYSICAL REVIEW LETTERS 2019; 122:194501. [PMID: 31144923 DOI: 10.1103/physrevlett.122.194501] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/11/2019] [Indexed: 06/09/2023]
Abstract
The fluid flow inside a thin liquid film can be dramatically modified by the hydrodynamic boundary condition at the interfaces. Aqueous systems can be easily contaminated by trace amounts of impurities, rendering the air-liquid interface immobile, thereby significantly resisting the fluid flow. Using high speed interferometry, rapid thinning of the liquid film, on the order of the collision speed, was observed between two fast approaching air bubbles in water, indicating negligible resistance and a fully mobile boundary condition at the air-water interface. By adding trace amounts of surfactants that changed the interfacial tension by 10^{-4} N/m, a transition from mobile to immobile was observed. This provides a fundamental explanation why the bubble coalescence time can vary by over 3 orders of magnitude.
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Affiliation(s)
- Bo Liu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada
| | - Rogerio Manica
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada
| | - Qingxia Liu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada
| | - Evert Klaseboer
- Institute of High Performance Computing, 1 Fusionopolis Way, Singapore 138632
| | - Zhenghe Xu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada and Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guangyuan Xie
- Department of Chemical Engineering, China University of Mining and Technology, Xuzhou 221116, China
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