Role of Surface Diffusion for the Drainage and Hydrodynamic Stability of Thin Liquid Films

Stoyanov, Simeon D.; Denkov, Nikolai D.

doi:10.1021/la001214x

Cited by 35 publications

(31 citation statements)

References 29 publications

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“…2). Note that due to the small drop size and the related faster thinning of the emulsion films (see eqn (14) below), the emulsions are affected much more than foams by the possible effects of the surface forces acting in the films, which makes very difficult the quantitative analysis of rheological data. Therefore, we will not discuss here the results obtained with such emulsions.…”

Section: 1723mentioning

confidence: 99%

“…), because the foam behaviour is governed by relatively well understood interplay of capillary effects and viscous friction in the foam films, formed between neighbouring bubbles. 1,[6][7][8][9][10][11][12][13][14][15][16][17][18] In addition, the relatively large bubble size allows direct optical observation of the dynamics of individual bubbles in flowing foams. [18][19][20][21] All these circumstances provide unique possibility for detailed theoretical modelling and experimental studies of foams at a microstructural level, which is impossible for the other systems of interest.…”

Section: Introductionmentioning

confidence: 99%

“…The numerical calculations showed that the energy dissipation in the meniscus region could be neglected in most cases and that the effect of surface forces becomes significant at low shear rates, when the thickness of the dynamic foam films becomes comparable to the range of surface forces. The latter effect is more important for emulsions and foams containing very small bubbles, due to the strong dependence of the rate of film thinning on the film diameter, see eqn (14) below. Most interestingly, the theoretical analysis of the effect of attractive surface forces (e.g., of van der Waals or depletion interactions) provided a direct mechanistic explanation of the observed ''jamming'' (liquid-tosolid transition) upon decrease of the shear rate, when the foam yield stress is reached.…”

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confidence: 99%

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The role of surfactant type and bubble surface mobility in foam rheology

et al. 2009

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This paper is an overview of our recent understanding of the effects of surfactant type and bubble surface mobility on foam rheological properties. The focus is on the viscous friction between bubbles in steadily sheared foams, as well as between bubbles and confining solid wall. Large set of experimental results is reviewed to demonstrate that two qualitatively different classes of surfactants can be clearly distinguished. The first class is represented by the typical synthetic surfactants (such as sodium dodecylsulfate) which are characterised with low surface modulus and fast relaxation of the surface tension after a rapid change of surface area. In contrast, the second class of surfactants exhibits high surface modulus and relatively slow relaxation of the surface tension. Typical examples for this class are the sodium and potassium salts of fatty acids (alkylcarboxylic acids), such as lauric and myristic acids. With respect to foam rheology, the second class of surfactants leads to significantly higher viscous stress and to different scaling laws of the shear stress vs. shear rate in flowing foams. The reasons for these differences are discussed from the viewpoint of the mechanisms of viscous dissipation of energy in sheared foams and the respective theoretical models. The process of bubble breakup in sheared foams (determining the final bubble-size distribution after foam shearing) is also discussed, because the experimental results and their analysis show that this phenomenon is controlled by foam rheological properties.

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Section: 1723mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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The role of surfactant type and bubble surface mobility in foam rheology

et al. 2009

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“…23). Hence, from the general definitions of the surface diffusion flux (28,29) and the electrochemical potential (23,24), and from the leading-order concentration distribution [6] the following simple relationship is obtained:…”

Section: Mass Balance Of Components and Electric Potential Distributionmentioning

confidence: 99%

Influence of Ionic Surfactants on the Drainage Velocity of Thin Liquid Films

Valkovska

Danov

2001

Journal of Colloid and Interface Science

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“…[30][31][32] Christenson and Yaminsky 31 suggested that the elastic response of the interface to changes in film thickness increases the coalescence time in electrolyte solutions compared to pure liquids (the Marangoni effect). The important quantity for this effect is the magnitude of dγ/dc or (dγ/dc) 2 .…”

Section: Table 1 Mass-transfer Enhancement For Added Electrolytes Anmentioning

confidence: 99%

Effect of Electrolytes on CO−Water Mass Transfer

Zhu

Shanks

Heindel

2009

Ind. Eng. Chem. Res.

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The influence of various electrolytes such as sulfate, nitrate, and chloride on CO-water mass transfer was investigated in this study. The results indicate that the enhancement in the CO-water volumetric masstransfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfatecontaining electrolytes showed stronger enhancement. By measuring both the CO-water volumetric masstransfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas-liquid interfacial area, resulting in CO-water masstransfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO-water interfacial area were both increased. KeywordsMechanical Engineering, baseline systems, functionalized, gas bubbles, gas liquids, interfacial areas, masstransfer coeficients, water mass, chlorine compounds, coalescence, mass transfer The influence of various electrolytes such as sulfate, nitrate, and chloride on CO-water mass transfer was investigated in this study. The results indicate that the enhancement in the CO-water volumetric masstransfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO-water volumetric mass-transfer coefficient (k L a) and the mass-transfer coefficient (k L ), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas-liquid interfacial area, resulting in CO-water mass-transfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO-water interfacial area were both increased.

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Role of Surface Diffusion for the Drainage and Hydrodynamic Stability of Thin Liquid Films

Cited by 35 publications

References 29 publications

The role of surfactant type and bubble surface mobility in foam rheology

The role of surfactant type and bubble surface mobility in foam rheology

Influence of Ionic Surfactants on the Drainage Velocity of Thin Liquid Films

Effect of Electrolytes on CO−Water Mass Transfer

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