The effect of a surface-active agent on mass transfer in falling drop extraction

Lindland, K.P.; Terjesen, S.G.

doi:10.1016/0009-2509(56)85001-x

Cited by 73 publications

(23 citation statements)

References 11 publications

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“…This effect rises gradually with alcohol molecular weight (Jamialahmadi and Miiller-Steinhagen, 1992). The decrease of surface tension in the presence of alcohol is negligible or at least not sufficient to explain the magnitude of this phenomenon; this difference is due to the reduction of the bubble-rise velocity, as suggested by several authors (Lindland and Terjesen, 1965;Raymond and Zieminski, 1971;Clift et al, 1978;Kelkar et al, 1983). Another point of industrial interest concerns the effect of the sparger on the bubble size, which has been reported in some articles (Chaumat et al, 2007;McClure et al, 2016).…”

Section: Introductionmentioning

confidence: 93%

Hydrodynamics and bubble size in bubble columns: Effects of contaminants and spargers

Gemello

Plais

Augier

et al. 2018

Chemical Engineering Science

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The simulation of bubble columns operating under the heterogeneous regime is an ambitious challenge, due to the difficulty of predicting accurately hydrodynamics and bubble size distributions, that requires experimental data for model validation. Gas fraction distributions, liquid and gas velocity profiles and bubble size distributions across bubble columns are deeply interconnected in these systems and only a comprehensive study allows the links between them to be understood. This work reports experimental data obtained by measuring bubble sizes with an innovative technique based on the cross correlation between two optical probes. Particular attention is given

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Section: Introductionmentioning

confidence: 93%

Hydrodynamics and bubble size in bubble columns: Effects of contaminants and spargers

Gemello

Plais

Augier

et al. 2018

Chemical Engineering Science

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“…The assumption will be made here that transfer during the formation of drops at the end of a jet is the same as at a nozzle tip. We therefore assume that Skelland and Minhas' (1971) If the coalescence interface is kept at the narrow exit of the extraction column, the mass transfer during drop coalescence can be neglected as suggested by Minhas (1969) and by Lindland and Terjesen (1956).…”

Section: Mass Transfer Theorymentioning

confidence: 99%

Dispersed phase mass transfer during drop formation under jetting conditions

Skelland

Huang

1977

AIChE Journal

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“…(iii) Measurements of the decrease in interphase mass transfer between the bubble or drop phase and the continuous phase as surfactant is added to the system. This is attributed to the increase in the boundary layer thickness around the fluid particle and the reduction in internal circulation as the interfacial mobility is decreased by the adsorption of surfactant (Garner & Hale 1953;Garner & Skelland 1955;Holm & Terjesen 1955;Lindland & Terjesen 1956;Boye-Christensen & Terjesen 1958;Boye-Christensen & Terjesen 1959;Raymond & Zieminski 1971;Huang & Kintner 1969;Beitel & Heideger 1971;Mekasut, Molinier & Angelino 1978;Skelland, Woo & Ramsay 1987). (iv) Measurements of the terminal velocities in systems in which surfactants are intentionally added.…”

Section: Introductionmentioning

confidence: 99%

Theory and experiments on the stagnant cap regime in the motion of spherical surfactant-laden bubbles

2006

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The buoyant motion of a bubble rising through a continuous liquid phase can be retarded by the adsorption onto the bubble surface of surfactant dissolved in the liquid phase. The reason for this retardation is that adsorbed surfactant is swept to the trailing pole of the bubble where it accumulates and lowers the surface tension relative to the front end. The difference in tension creates a Marangoni force which opposes the surface flow, rigidifies the interface and increases the drag coefficient. Surfactant molecules adsorb onto the bubble surface by diffusing from the bulk to the sublayer of liquid adjoining the surface, and kinetically adsorbing from the sublayer onto the surface. The surface surfactant distribution which defines the Marangoni force is determined by the rate of kinetic adsorption and bulk diffusion relative to the rate of surface convection. In the limit in which the rate of either kinetic or diffusive transport of surfactant to the bubble surface is slow relative to surface convection and surface diffusion is also slow, surfactant collects in a stagnant cap at the back end of the bubble while the front end is stress free and mobile. The size of the cap and correspondingly the drag coefficient increases with the bulk concentration of surfactant until the cap covers the entire surface and the drag coefficient is that of a bubble with a completely tangentially immobile surface. Previous theoretical research on the stagnant cap regime has not studied in detail the competing roles of bulk diffusion and kinetic adsorption in determining the size of the stagnant cap angle, and there have been only a few studies which have attempted to quantitatively correlate simulations with measurements.This paper provides a more complete theoretical study of and a validating set of experiments on the stagnant cap regime. We solve numerically for the cap angle and drag coefficient as a function of the bulk concentration of surfactant for a spherical bubble rising steadily with inertia in a Newtonian fluid, including both bulk diffusion and kinetic adsorption. For the case of diffusion-limited transport (infinite adsorption kinetics), we show clearly that very small bulk concentrations can immobilize the entire surface, and we calculate the critical concentrations which immobilize the surface as a function of the surfactant parameters. We demonstrate that the effect of kinetics is to reduce the cap angle (hence reduce the drag coefficient) for a given bulk concentration of surfactant. We also present experimental results on the drag of a bubble rising in a glycerol–water mixture, as a function of the dissolved concentration of a polyethoxylated non-ionic surfactant whose bulk diffusion coefficient and a lower bound on the kinetic rate constants have been obtained separately by measuring the reduction in dynamic tension as surfactant adsorbs onto a clean interface. For low concentrations of surfactant, the experiments measure drag coefficients which are intermediate between the drag coefficient of a bubble whose surf...

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The effect of a surface-active agent on mass transfer in falling drop extraction

Cited by 73 publications

References 11 publications

Hydrodynamics and bubble size in bubble columns: Effects of contaminants and spargers

Hydrodynamics and bubble size in bubble columns: Effects of contaminants and spargers

Dispersed phase mass transfer during drop formation under jetting conditions

Theory and experiments on the stagnant cap regime in the motion of spherical surfactant-laden bubbles

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