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Pan Y, Gresham I, Bournival G, Prescott S, Ata S. Synergistic effects of frothers, collector and salt on bubble stability. POWDER TECHNOL 2022. [DOI: 10.1016/j.powtec.2021.117028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Amani P, Karakashev SI, Grozev NA, Simeonova SS, Miller R, Rudolph V, Firouzi M. Effect of selected monovalent salts on surfactant stabilized foams. Adv Colloid Interface Sci 2021; 295:102490. [PMID: 34385000 DOI: 10.1016/j.cis.2021.102490] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/15/2021] [Accepted: 07/18/2021] [Indexed: 12/11/2022]
Abstract
Surfactant-stabilized foams have been at the centre of scientific research for over a century due to their ubiquitous applications in different industries. Many of these applications involve inorganic salts either due to their natural presence (e.g. use of seawater in froth floatation) or their addition (e.g. in cosmetics) to manipulate foam characteristics for the best outcomes. This paper provides a clear understanding of the effect of salts on surfactant-stabilized foams through a critical literature survey of this topic. Available literature shows a double effect of salts (LiCl, NaCl and KCl) on foam characteristics in the presence of surfactants. To elucidate the underlying mechanisms of the stabilizing effect of salts on foams, the effect of salts on surfactant-free thin liquid films is first discussed, followed by a discussion on the effect of salts on surfactant-stabilized foams with the focus on anionic surfactants. We discuss two distinctive salt concentrations, salt transition concentration in surfactant-free solutions and salt critical concentration in surfactant-laden systems to explain their effects. Using the available data in literature supported by dedicated experiments, we demonstrate the destabilizing effect of salts on foams at and above their critical concentrations in the presence of anionic surfactants. This effect is attributed to retarding the adsorption of the surfactant molecules at the interface due to the formation of nano and micro-scale aggregates.
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Affiliation(s)
- Pouria Amani
- School of Chemical Engineering, The University of Queensland, St. Lucia 4072, Australia
| | | | - Nikolay A Grozev
- Department of Physical Chemistry, University of Sofia, Sofia 1164, Bulgaria
| | | | - Reinhard Miller
- Department of Physics, Technische Universität Darmstadt, Darmstadt 64289, Germany
| | - Victor Rudolph
- School of Chemical Engineering, The University of Queensland, St. Lucia 4072, Australia
| | - Mahshid Firouzi
- Newcastle Institute for Energy and Resources, The Uniersity of Newcastle, Callaghan 2308, Australia.
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3
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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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4
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Han S, Nguyen AV, Kim K, Park JK, You K. Quantitative Analysis of Attachment Time of Air Bubbles to Solid Surfaces in Water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:616-626. [PMID: 32031822 DOI: 10.1021/acs.langmuir.9b02773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The attachment of air bubbles to solid surfaces in water is encountered in many natural processes and industrial applications. It has been established that the attachment can occur between hydrophobic surfaces and air bubbles. In this paper, we present novel experimental results to quantify the attachment in terms of the attachment time. We show that the attachment time can be determined from either the transient force curve or the transient film thickness. These techniques for determining the attachment time are based on the fact that the rupture of a thin liquid film produces a large attachment force and a rapid expansion of the three-phase contact radius in comparison with the expansion of the film radius. The experimental results are quantitatively analyzed using thin-film drainage theory and intermolecular forces, which include the advanced multilayer van der Waals force and the electrical double-layer force. The advanced van der Waals force theory allows us to incorporate the effect of interfacial gas enrichment (IGE) of dissolved gas in water at hydrophobic surfaces on the bubble-surface attachment. Critically, if the presence of IGE is ignored, the experimental results do not agree with the theory. Finally, IGE is shown to be a significant factor in controlling hydrophobic attraction between an air bubble and a hydrophobic surface and their attachment.
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Affiliation(s)
- Seongsoo Han
- Convergence Research Center for Development of Mineral Resources (DMR), Korea Institute of Geoscience and Mineral Resources (KIGAM), 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Republic of Korea
- Department of Earth Resources and Environmental Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Anh V Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Kwanho Kim
- Convergence Research Center for Development of Mineral Resources (DMR), Korea Institute of Geoscience and Mineral Resources (KIGAM), 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Republic of Korea
| | - Jai-Koo Park
- Department of Earth Resources and Environmental Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Kwangsuk You
- Convergence Research Center for Development of Mineral Resources (DMR), Korea Institute of Geoscience and Mineral Resources (KIGAM), 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Republic of Korea
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5
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Karakashev SI, Firouzi M, Wang J, Alexandrova L, Nguyen AV. On the stability of thin films of pure water. Adv Colloid Interface Sci 2019; 268:82-90. [PMID: 30954719 DOI: 10.1016/j.cis.2019.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 03/08/2019] [Indexed: 11/30/2022]
Abstract
The stability of water films has been the focus of many researchers in the recent decades. Unfortunately, there is no consensus on the stability of these foam films or on the mechanisms responsible for stabilizing water films. This paper examines the reported results on this matter and scrutinizes them based on speciation analysis of the dissolved species and the recent achievements in the adsorption of inorganic ions on the air/water interface. Our results confirm the key role of surface contamination, interface approach velocity and evaporation in the drainage and lifetime of these water films. It confirms the stabilizing effect of contamination and the destabilizing effect of air-water interface approach velocity. Moreover, the negative sign of the surface/zeta potential of the air/water interface and its dependence on the pH value were explained.
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Wang J, Teo AJT, Tan SH, Evans GM, Nguyen NT, Nguyen AV. Influence of Interfacial Gas Enrichment on Controlled Coalescence of Oil Droplets in Water in Microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3615-3623. [PMID: 30747538 DOI: 10.1021/acs.langmuir.8b03486] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Interfacial gas enrichment (IGE) of dissolved gases in water is shown to govern the strong attraction between solid hydrophobic surfaces of an atomic force microscopy (AFM) colloidal probe and solid substrate. However, the role of IGE in controlling the attraction between fluid-fluid interfaces of foam films and emulsion films is difficult to establish by AFM techniques because of the extremely fast coalescence. Here, we applied droplet-based microfluidics to capture the fast coalescence event under the creeping flow condition and quantify the effect of IGE on the drainage and stability of water films between coalescing oil droplets. The amount of dissolved gases is controlled by partially degassing the oil phase. When the amount of dissolved gases (oxygen) in oil decreases (from 7.89 to 4.59 mg/L), the average drainage time of coalescence significantly increases (from 19 to 50 ms). Our theoretical quantification of the coalescence by incorporating IGE into the multilayer van der Waals attraction theory confirms the acceleration of film drainage dynamics by the van der Waals attractive force generated by IGE. The thickness of the IGE layer decreases from 5.5 to 4.9 nm when the amount of dissolved gas decreases from 7.89 to 4.59 mg/L. All these results establish the universal role of dissolved gases in governing the strong attraction between particulate hydrophobic interfaces.
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Affiliation(s)
- Jianlong Wang
- School of Chemical Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Adrian J T Teo
- Queensland Micro- and Nanotechnology Centre , Griffith University , Brisbane , Queensland 4111 , Australia
| | - Say H Tan
- Queensland Micro- and Nanotechnology Centre , Griffith University , Brisbane , Queensland 4111 , Australia
| | - Geoffrey M Evans
- School of Engineering , The University of Newcastle , Callaghan , New South Wales 2308 , Australia
| | - Nam-Trung Nguyen
- Queensland Micro- and Nanotechnology Centre , Griffith University , Brisbane , Queensland 4111 , Australia
| | - Anh V Nguyen
- School of Chemical Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia
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7
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Heterocoagulation of shale particles and bubbles in the presence of ionic surfactants. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.06.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Vakarelski IU, Manica R, Li EQ, Basheva ES, Chan DYC, Thoroddsen ST. Coalescence Dynamics of Mobile and Immobile Fluid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2096-2108. [PMID: 29328665 DOI: 10.1021/acs.langmuir.7b04106] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Coalescence dynamics between deformable bubbles and droplets can be dramatically affected by the mobility of the interfaces with fully tangentially mobile bubble-liquid or droplet-liquid interfaces expected to accelerate the coalescence by orders of magnitude. However, there is a lack of systematic experimental investigations that quantify this effect. By using high speed camera imaging we examine the free rise and coalescence of small air-bubbles (100 to 1300 μm in diameter) with a liquid interface. A perfluorocarbon liquid, PP11, is used as a model liquid to investigate coalescence dynamics between fully mobile and immobile deformable interfaces. The mobility of the bubble surface was determined by measuring the terminal rise velocity of small bubbles rising at Reynolds numbers, Re, less than 0.1 and the mobility of free PP11 surface by measuring the deceleration kinetics of the small bubble toward the interface. Induction or film drainage times of a bubble at the mobile PP11-air surface were found to be more than 2 orders of magnitude shorter compared to the case of bubble and an immobile PP11-water interface. A theoretical model is used to illustrate the effect of hydrodynamics and interfacial mobility on the induction time or film drainage time. The results of this study are expected to stimulate the development of a comprehensive theoretical model for coalescence dynamics between two fully or partially mobile fluid interfaces.
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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
| | - Rogerio Manica
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Er Qiang Li
- Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal, 23955-6900, Saudi Arabia
- Department of Modern Mechanics, University of Science and Technology of China , Hefei 230027, China
| | - Elka S Basheva
- Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University , 1164 Sofia, Bulgaria
| | - Derek Y C Chan
- School of Mathematics and Statistics, University of Melbourne , Parkville, VIC 3010, Australia
- Department of Mathematics, Swinburne University of Technology , Hawthorn, VIC 3122, Australia
| | - 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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Novev JK, Panchev N, Slavchov RI. Evaporating foam films of pure liquid stabilized via the thermal Marangoni effect. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2017.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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The Gibbs-Marangoni stress and nonDLVO forces are equally important for modeling bubble coalescence in salt solutions. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2016.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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11
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Firouzi M, Howes T, Nguyen AV. A quantitative review of the transition salt concentration for inhibiting bubble coalescence. Adv Colloid Interface Sci 2015; 222:305-18. [PMID: 25109881 DOI: 10.1016/j.cis.2014.07.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 07/20/2014] [Accepted: 07/20/2014] [Indexed: 10/25/2022]
Abstract
Some salts have been proven to inhibit bubble coalescence above a certain concentration called the transition concentration. The transition concentration of salts has been investigated and determined by using different techniques. Different mechanisms have also been proposed to explain the stabilizing effect of salts on bubble coalescence. However, as yet there is no consensus on a mechanism which can explain the stabilizing effect of all inhibiting salts. This paper critically reviews the experimental techniques and mechanisms for the coalescence of bubbles in saline solutions. The transition concentrations of NaCl, as the most popularly used salt, determined by using different techniques such as bubble swarm, bubble pairs, and thin liquid film micro-interferometry were analyzed and compared. For a consistent comparison, the concept of TC95 was defined as a salt concentration at which the "percentage coalescence" of bubbles reduces by 95% relative to the highest (100% in pure water) and lowest (in high-salt concentration) levels. The results show a linear relationship between the TC95 of NaCl and the reciprocal of the square root of the bubble radius. This relationship holds despite different experimental techniques, salt purities and bubble approach speeds, and highlights the importance of the bubble size in bubble coalescence. The available theoretical models for inhibiting effect of salts have also been reviewed. The failure of these models in predicting the salt transition concentration commands further theoretical development for a better understanding of bubble coalescence in salt solutions.
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Azadi M, Nguyen AV, Yakubov GE. Attractive forces between hydrophobic solid surfaces measured by AFM on the first approach in salt solutions and in the presence of dissolved gases. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1941-1949. [PMID: 25627159 DOI: 10.1021/la504001z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Interfacial gas enrichment of dissolved gases (IGE) has been shown to cover hydrophobic solid surfaces in water. The atomic force microscopy (AFM) data has recently been supported by molecular dynamics simulation. It was demonstrated that IGE is responsible for the unexpected stability and large contact angle of gaseous nanobubbles at the hydrophobic solid-water interface. Here we provide further evidence of the significant effect of IGE on an attractive force between hydrophobic solid surfaces in water. The force in the presence of dissolved gas, i.e., in aerated and nonaerated NaCl solutions (up to 4 M), was measured by the AFM colloidal probe technique. The effect of nanobubble bridging on the attractive force was minimized or eliminated by measuring forces on the first approach of the AFM probe toward the flat hydrophobic surface and by using high salt concentrations to reduce gas solubility. Our results confirm the presence of three types of forces, two of which are long-range attractive forces of capillary bridging origin as caused by either surface nanobubbles or gap-induced cavitation. The third type is a short-range attractive force observed in the absence of interfacial nanobubbles that is attributed to the IGE in the form of a dense gas layer (DGL) at hydrophobic surfaces. Such a force was found to increase with increasing gas saturation and to decrease with decreasing gas solubility.
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Affiliation(s)
- Mehdi Azadi
- School of Chemical Engineering and ‡ARC Centre of Excellence in Plant Cell Walls, The University of Queensland , Brisbane, Queensland 4072, Australia
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13
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Peng T, Firouzi M, Li Q, Peng K. Surface force at the nano-scale: observation of non-monotonic surface tension and disjoining pressure. Phys Chem Chem Phys 2015; 17:20502-7. [DOI: 10.1039/c5cp03050a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The disjoining pressures of thin aqueous salt films at different salt concentrations and temperatures were calculated using MD simulations.
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Affiliation(s)
- Tiefeng Peng
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- College of Aerospace Engineering
- Chongqing University
- Chongqing 400044
- China
| | - Mahshid Firouzi
- School of Chemical Engineering
- The University of Queensland
- Brisbane
- Australia
| | - Qibin Li
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- College of Aerospace Engineering
- Chongqing University
- Chongqing 400044
- China
| | - Kang Peng
- State Key Laboratory of Coal Mine Disaster Dynamics and Control
- College of Aerospace Engineering
- Chongqing University
- Chongqing 400044
- China
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15
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Ishida N, Kusaka Y, Ushijima H. Hydrophobic attraction between silanated silica surfaces in the absence of bridging bubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13952-13959. [PMID: 22931235 DOI: 10.1021/la303037d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The interaction forces between silanated silica surfaces on which there were neither nanobubbles nor a gas phase were measured using colloidal probe atomic force microscopy (AFM). To obtain hydrophobic surfaces without attached nanobubbles, an aqueous solution was introduced between the surfaces after an exchange process involving several solvents. In the approaching force curves obtained, an attractive force was observed from a distance of 10-25 nm, indicating the existence of an additional attractive force stronger than the van der Waals attraction. In the retracting force curves, a strong adhesion force was observed, and the value of this force was comparable to that of the capillary bridging force. The data clearly showed that although the bridging of nanobubbles is responsible for long-range hydrophobic attraction, there also exists an additional attractive force larger than the van der Waals attraction between hydrophobic surfaces without nanobubbles. Both the ionic strength and the temperature of the solution had little influence on the force. The possible origin of the force is discussed on the basis of the obtained results.
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Affiliation(s)
- Naoyuki Ishida
- Flexible Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Japan.
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Horn RG, Del Castillo LA, Ohnishi S. Coalescence map for bubbles in surfactant-free aqueous electrolyte solutions. Adv Colloid Interface Sci 2011; 168:85-92. [PMID: 21640320 DOI: 10.1016/j.cis.2011.05.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/08/2011] [Accepted: 05/10/2011] [Indexed: 10/18/2022]
Abstract
Factors influencing bubble coalescence in surfactant-free aqueous electrolyte solutions are considered in this compilation of literature results. These factors include viscous and inertial thin film drainage, surface deformation, surface elasticity, mobility or otherwise of the air-water interface, and disjoining pressure. Several models from the literature are discussed, with particular attention paid to predictions of transitions between regions where behaviour is qualitatively different. The transitions are collated onto a single chart with salt concentration and bubble approach speed as the axes. This creates a map of the regions in which different mechanisms operate, giving an overall picture of bubble coalescence behaviour over a wide range of concentration and speed. Only mm-size bubbles in water and NaCl solutions are discussed in this initial effort at creating such a map. Data on bubble coalescence or non-coalescence are collected from the literature and plotted on the same map, generally aligning well with the predicted transitions and thus providing support for the theoretical reasoning that went into creating the coalescence map.
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Samanta S, Ghosh P. Coalescence of air bubbles in aqueous solutions of alcohols and nonionic surfactants. Chem Eng Sci 2011. [DOI: 10.1016/j.ces.2011.06.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Del Castillo LA, Ohnishi S, Horn RG. Inhibition of bubble coalescence: Effects of salt concentration and speed of approach. J Colloid Interface Sci 2011; 356:316-24. [DOI: 10.1016/j.jcis.2010.12.057] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 12/16/2010] [Accepted: 12/17/2010] [Indexed: 10/18/2022]
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Yaminsky VV, Ohnishi S, Vogler EA, Horn RG. Stability of aqueous films between bubbles. Part 1. The effect of speed on bubble coalescence in purified water and simple electrolyte solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8061-74. [PMID: 20146434 PMCID: PMC2876226 DOI: 10.1021/la904481d] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Film thinning experiments have been conducted with aqueous films between two air phases in a thin film pressure balance. The films are free of added surfactant but simple NaCl electrolyte is added in some experiments. Initially the experiments begin with a comparatively large volume of water in a cylindrical capillary tube a few millimeters in diameter, and by withdrawing water from the center of the tube the two bounding menisci are drawn together at a prescribed rate. This models two air bubbles approaching at a controlled speed. In pure water, the results show three regimes of behavior depending on the approach speed; at slow speed (<1 microm/s) it is possible to form a flat film of pure water, approximately 100 nm thick, that is stabilized indefinitely by disjoining pressure due to repulsive double-layer interactions between naturally charged air/water interfaces. The data are consistent with a surface potential of -57 mV on the bubble surfaces. At intermediate approach speed (approximately 1-150 microm/s), the films are transiently stable due to hydrodynamic drainage effects, and bubble coalescence is delayed by approximately 10-100 s. At approach speeds greater than approximately 150 microm/s, the hydrodynamic resistance appears to become negligible, and the bubbles coalesce without any measurable delay. Explanations for these observations are presented that take into account Derjaguin-Landau-Verwey-Overbeek and Marangoni effects entering through disjoining pressure, surface mobility, and hydrodynamic flow regimes in thin film drainage. In particular, it is argued that the dramatic reduction in hydrodynamic resistance is a transition from viscosity-controlled drainage to inertia-controlled drainage associated with a change from immobile to mobile air/water interfaces on increasing the speed of approach of two bubbles. A simple model is developed that accounts for the boundaries between different film stability or coalescence regimes. Predictions of the model are consistent with the data, and the effects of adding electrolyte can be explained. In particular, addition of electrolyte at high concentration inhibits the near-instantaneous coalescence phenomenon, thereby contributing to increased foam film stability at high approach speeds, as reported in previous literature. This work highlights the significance of bubble approach speed as well as electrolyte concentration in affecting bubble coalescence.
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Affiliation(s)
- Vassili V. Yaminsky
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Satomi Ohnishi
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Erwin A. Vogler
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802-5005
| | - Roger G. Horn
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
- Institute of Research Training, Deakin University, Burwood, Victoria 3125, Australia
- corresponding author
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