Effect of cosurfactant on the free-drainage regime of aqueous foams.
15 Dec 2005-Vol. 292, Iss: 2, pp 544-547
TL;DR: The results confirm that a drainage regime corresponding to a high surface mobility can indeed be found for such small bubbles, and show that an increase in the cosurfactant content can induce a transition to a low surface mobility drainage regime, evidencing that the relevant control parameter for drainage regimes includes both bubble size and interfacial contributions.
Abstract: We report results of drainage in aqueous foams of small bubble size D (D = 180 µm) prepared with SDS-dodecanol solutions. We have performed free-drainage experiments in which local drainage rates are measured by electrical conductivity and by light scattering techniques. We have investigated the role of the surfactant–cosurfactant mass ratio on the drainage regime. The results confirm that a drainage regime corresponding to a high surface mobility can indeed be found for such small bubbles, and show that an increase in the cosurfactant content can induce a transition to a low surface mobility drainage regime. We show that the transition is not linked to variations of the bulk properties, but rather to variations of the interfacial properties. However, the results show that the added amount of dodecanol to trigger the transition is quite high, evidencing that the relevant control parameter for drainage regimes includes both bubble size and interfacial contributions.
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24 Jan 2018
TL;DR: In this article, the effect of surfactant on foam properties was investigated using a commercially available instrument, Foam Scan, which determined simultaneously the foaming time, foam volume, the liquid content of foam and bubble size distribution.
Abstract: Surfactants known as frothers are widely used in froth flotation to produce small bubbles and stabilize the froth, meanwhile, froth stability plays an important role in determining the product grade and recovery achieved from a mineral flotation process, and therefore it is of great significance to study the effect of surfactant on foam properties. However, foam properties, especially foam stability concerning liquid content of foam and evolution of bubble size, in flotation has received little attention. In this study, we intensively investigated the foamability and foam stability of different concentration cetyltrimethylammonium bromide (CTAB) solutions. Experiments were carried out using a commercially available instrument, Foam Scan, which determined simultaneously the foaming time, foam volume, the liquid content of foam and bubble size distribution. Particularly, the evolution of bubble size can be allowed to determine at a regular time interval. The results showed that as an increase in CTAB concentration, the foamability continuously increased till reached a constant at a critical micelle concentration (CMC), however, the foam stability initially increased and then presented a little decrease when the tested concentrations were larger than its CMC. An argument based on foam drainage, bubble coalescence and coarsening processes is proposed to account for the effect of CTAB concentration foam properties.
11 citations
TL;DR: In this paper, the rheological behavior of microbubbles has been examined using their flow index in capillary tubes, in order to evaluate the stability of microbubbles.
9 citations
TL;DR: In this article, a brief review article is devoted to all the aspects related to hydrodynamics of foams, focusing on the methods for studying the basic structural units of the foams.
Abstract: This brief review article is devoted to all the aspects related to hydrodynamics of foams. For this reason, we focused at first on the methods for studying the basic structural units of the foams—the foam films (FF) and the Plateau borders (PB), thus reviewing the literature about their drainage. After this, we scrutinized in detail the Derjaguin’s works on the electrostatic disjoining pressure along with its Langmuir’s interpretation, the microscopic and macroscopic approaches in the theory of the van der Waals disjoining pressure, the DLVO theory, the steric disjoining pressure of de Gennes, and the more recent works on non-DLVO forces. The basic methods for studying of foam drainage are presented as well. Engineering and other applications of foam are reviewed as well. All these aspects are presented from retrospective and perspective viewpoints.
9 citations
TL;DR: In this paper, a multi-point electrical resistance measurement technique has been applied for characterization of the drainage regimes and quantifying stability within standing foams, and the capacity of the technique was confirmed by the estimation of macroscopic drainage rates for aqueous foams stabilized with sodium dodecyl sulfate.
Abstract: Foam drainage regimes are significantly associated with the nature of the hydrodynamic resistance in foam structure. A multi-point electrical resistance measurement technique has been applied for characterization of the drainage regimes and quantifying stability within standing foams. The capacity of the technique was confirmed by the estimation of macroscopic drainage rates for aqueous foams stabilized with sodium dodecyl sulfate. The drainage of sodium dodecylbenzenesulfonate, a commercial form of linear alkylbenzene sulfonate that is the most frequently used in household detergents was studied in detail by two complementary methods (forced and free drainage). The experimental data could be fitted using a power-law with an exponent of 1/3 for forced drainage and of 1.0 for free drainage. These data indicate the following drainage behavior: mobile bubble surfaces, causing plug-like flow within Plateau borders, thus dissipation mainly occurs inside the nodes. This research introduced an accurate method for quantifying foam stability that can be assessed by variations of real-time measured foam heights that incorporate the evolution of the liquid content. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3143–3150, 2014
7 citations
TL;DR: In this article, the effects of bubble void fraction and size distribution on the viscosity of micro-bubbles were investigated, and it was found that bubble size distribution in the range (1-12 µm) used in this study does not affect the visco-temporal properties of microbubbles.
Abstract: The viscosity of microbubbles has been measured in capillary tubes. Experiments were conducted in tubes of different diameters and lengths, with a constant microbubble concentration. The effects of bubble void fraction and size distribution on the viscosity of microbubbles were also investigated. Microbubbles demonstrate shear-thinning non-Newtonian behavior. The viscosity of microbubbles decreases with a decrease in tube diameter and bubble void fraction, and with an increase in tube length. Although viscosity changes with tube dimensions, the flow index (n′) is only influenced by the microbubble void fraction. It is also found that bubble size distribution in the range (1–12 µm) used in this study does not affect the viscosity of microbubbles. The data were then used to develop a correlation to predict viscosity of microbubbles, which represents the experimental viscosity data with an absolute average relative deviation less than 1.3%. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2660–2669, 2014
3 citations
References
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Book•
01 Jan 1985
TL;DR: The forces between atoms and molecules are discussed in detail in this article, including the van der Waals forces between surfaces, and the forces between particles and surfaces, as well as their interactions with other forces.
Abstract: The Forces between Atoms and Molecules. Principles and Concepts. Historical Perspective. Some Thermodynamic Aspects of Intermolecular Forces. Strong Intermolecular Forces: Covalent and Coulomb Interactions. Interactions Involving Polar Molecules. Interactions Involving the Polarization of Molecules. van der Waals Forces. Repulsive Forces, Total Intermolecular Pair Potentials, and Liquid Structure. Special Interactions. Hydrogen-Bonding, Hydrophobic, and Hydrophilic Interactions. The Forces between Particles and Surfaces. Some Unifying Concepts in Intermolecular and Interparticle Forces. Contrasts between Intermolecular, Interparticle, and Intersurface Forces. van der Waals Forces between Surfaces. Electrostatic Forces between Surfaces in Liquids. Solvation, Structural and Hydration Forces. Steric and Fluctuation Forces. Adhesion. Fluid-Like Structures and Self-Assembling Systems. Micelles, Bilayers, and Biological Membranes. Thermodynamic Principles of Self-Assembly. Aggregation of Amphiphilic Molecules into Micelles, Bilayers, Vesicles, and Biological Membranes. The Interactions between Lipid Bilayers and Biological Membranes. References. Index.
18,048 citations
"Effect of cosurfactant on the free-..." refers background in this paper
...In fact, the effect of cosurfactant is to change the shape and size of the micelles [12]....
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Book•
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01 Jan 1999
TL;DR: In this article, the shape of single soap movies and bubble clusters is discussed, as well as the condUCTIVITY FORMULA of LEMLICH and PHYLLOTAXIS.
Abstract: PREFACE APPENDICES A. THE SHAPE OF SINGLE SOAP FILMS AND BUBBLES B. THE THEOREM OF LAMARLE C. BUBBLE CLUSTERS D. THE DECORATION THEORUM E. THE CONDUCTIVITY FORMULA OF LEMLICH F. THE DRAINAGE EQUATION G. PHYLLOTAXIS H. SIMULATION OF LIQUID FOAMS I. BIBLIOGRAPHY APPENDICES
1,275 citations
"Effect of cosurfactant on the free-..." refers background or methods in this paper
...Firs we use electrical conductometry [1], via a set of electrode installed along the foam container....
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...Foams are dispersions of gas bubbles in a liquid or s phase[1]....
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...They evolve in time three mechanisms: coarsening, drainage, and film rup During coarsening, smaller bubbles dissolve, while big ones grow in size due to gas diffusion across the liq films [1]....
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TL;DR: In this paper, a new experimental method is presented using fluorescein dye to determine the spatial and temporal variations of the liquid volume fraction in aqueous foams This method was used for quantitative studies of liquid redistribution (drainage) in three types of experiments: forced, free, and pulsed drainage Characteristic quantities, such as the drainage velocity, show power-law dependences on experimental parameters that are inconsistent with traditional foam drainage models based on Poiseuille-type flow in the liquid-carrying channels (Plateau borders) of the foam.
Abstract: A new experimental method is presented using fluorescein dye to determine the spatial and temporal variations of the liquid volume fraction in aqueous foams This method is used for quantitative studies of liquid redistribution (drainage) in three types of experiments: forced, free, and pulsed drainage Characteristic quantities, such as the drainage velocity, show power-law dependences on experimental parameters that are inconsistent with traditional foam drainage models based on Poiseuille-type flow in the liquid-carrying channels (Plateau borders) of the foam To obtain a theoretical description, the foam drainage equation is generalized using an energy argument which accounts for viscous dissipation in both the channels and the nodes (or vertices, which are the junctions of four channels) of the liquid network Good agreement with results for all three types of drainage experiments is found when using this new model in the limit where the dissipation is dominated by the nodes
360 citations
225 citations
"Effect of cosurfactant on the free-..." refers background in this paper
...In fact, the effect of cosurfactant is to cha the shape and size of the micelles [12]....
[...]
TL;DR: In this article, a theoretical model for interstitial liquid flow in a stationary or moving foam was devised by relating the physical structure of the foam to the physical properties of the surfactant and the foam movement.
Abstract: A theoretical model for interstitial liquid flow in a stationary or moving foam was devised by relating the physical structure of the foam to the physical properties of the surfactant and the foam movement. This was accomplished through a differential momentum balance within a typical capillary (Plateau border) of noncircular cross section with finite surface viscosity at its boundaries. Velocity profiles were then calculated and integrated numerically for the randomly oriented capillaries so as to obtain the overall liquid flow through the foam in terms of the pertinent variables. Results are presented in a form suitable for estimating concentrations and flow rates of product and waste streams in foam fractionation.
222 citations