Effects of Surface Active Agents on Extraction from Droplets

Garner, F. H.; Skelland, A. H. P.

doi:10.1021/ie50553a019

Cited by 48 publications

(29 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Attempts to remedy this either by adding more stabilizing surfactant or by increasing the viscosity of the membrane phase both result in substantial reduction in solute permeability through the membrane and hence a reduction in extraction rate. This arises in the former case because of increased mechanical and adsorptive barriers to transfer at the interfaces between the membrane and the internal and external phases caused by the adsorbed extra surfactant (Garner and Skelland, 1956). Also, interfacial chemical reactions-as with the trapping reagent-are slowed down (Nakashio et al, 1988).…”

Section: February 1996mentioning

confidence: 99%

“…This not only removes some of the resistance to solute transfer across the phase interfaces offered by the adsorbed surfactant (Garner and Skelland, 1956), but also lessens the retarding effect of the surfactant on the chemical reaction rate (as with the trapping reagent) at these interfaces (Nakashio et al, 1988). Reduced surfactant is also known to promote the subsequent electrostatic demulsification (Hsu and Li, 1985).…”

Section: Aiche Journalmentioning

confidence: 99%

“…Boyadzhiev and Elenkov (1966) and Skelland and Kanel (1992b) have shown that at the low volume ratios of disperse (emulsion) phase to continuous phase used here the dominant transfer mechanism occurs during free travel of the drops (globules) around the vessel, and not during drop breakage or coalescence. However, during such free travel of the globules, their interior is essentially stagnant because of the combination of high interfacial tension between the organic membrane and the surrounding aqueous phase, the high concentration of surfactant in the membrane, and the small size of the globules (Garner and Skelland, 1956;Davies and Rideal, 1963;Skelland and Moeti, 1990; …”

Section: Vol 42 Nomentioning

confidence: 99%

See 2 more Smart Citations

A new solution to emulsion liquid membrane problems by non‐Newtonian conversion

Skelland¹,

Meng²

1996

AIChE Journal

Self Cite

View full text Add to dashboard Cite

Section: February 1996mentioning

confidence: 99%

Section: Aiche Journalmentioning

confidence: 99%

Section: Vol 42 Nomentioning

confidence: 99%

See 1 more Smart Citation

A new solution to emulsion liquid membrane problems by non‐Newtonian conversion

Skelland¹,

Meng²

1996

AIChE Journal

Self Cite

View full text Add to dashboard Cite

“…Monomer transfer from the droplets to the water phase is not impeded, because their surface is convered by only a small amount of emulsifier. 16 Monomer transfer through the water phase is governed by the diffusion flow, which is, in correlation to the droplet and particle sizes, described by the Smoluchowski e q~a t i 0 n . l~ The monomer flow from monomer droplets to the water phase and from the water phase into polymer particles depends on the droplet and particle sizes, concentration gradients, and diffusion coefficients.…”

Section: Resultsmentioning

confidence: 99%

Semicontinuous emulsion copolymerization of styrene and butyl acrylate

Šňupárek¹,

Krška²

1976

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

SynopsisSemicontinuous emulsion copolymerization of styrene and butyl acrylate with a constant rate of feed of monomer emulsion was investigated. The integral composition of the copolymer at the end of the feeding was different from the feed composition, and the difference was proportional to the monomer feeding rate. The closer the feed composition was to the composition at the azeotropic point, the lower was the sensitivity of the system to the feeding rate. At low feeding rates, the copolymerization proceeded at conversions of about 90-95%, and the composition of the copolymer was practically equal to that of the monomer feed. The reactivity ratios determined under these conditions were probably influenced by diffusion inside the growing polymermonomer particles.

show abstract

“…and Here Nwe is the Weber number, Nwe = p' v , "~ R"/u," (30) Equations (22) to (24), (28) and (29) comprise the set of boundary conditions which the bulk phase velocity distributions must satisfy at the phase interface.…”

Section: T = F ( E )mentioning

confidence: 99%

Creeping flow past a fluid globule when a trace of surfactant is present

Wasserman

Slattery

1969

AIChE Journal

View full text Add to dashboard Cite

The effects of a trace quantity of a surface-active agent on creeping flow past a bubble or droplet are investigated. The equations describing mass and momentum transfer are simultaneously solved by a perturbation technique, consistent with the jump mass and momentum batances a t the phase interface. The stream function for the velocity distribution is evaluated as an infinite series of spherical harmonics. Golerkin's method, which reduces the partial differential equation of continuity to a set of ordinary differential equations, is used to evaluate the concentration distribution of surfactant.A sample calculation is carried out for relative motion between an air bubble and an infinite body of water which contains a trace of isoamyl alcohol. The relative velocity of the water a t an infinite distance from the bubble is found to be highly sensitive to small changes in surfactant concentration from zero, although the bubble varies imperceptibly from a spherical shape.Consider a fluid globule which moves at a constant velocity under the action of gravity through a second immiscible phase. Hadamard and Rybczynski (1, p. 395) independently presented a solution to this problem which neglects interfacial effects, but their results failed to explain available experimental data for settling velocities.This led Boussinesq (2) to hypothesize that a skin which inhibits the internal circulation can form around a moving droplet. He described this quantitatively by a constitutive equation which expresses the stress in the interface as a linear function of the rate of deformation of the interface. This relationship, often called the Newtonian surface fluid model ( 3 to 6 ) , has two parameters in addition to surface tension: surface shear viscosity and surface dilatational viscosity. Acceptable laboratory measurements of these surface viscosities have not been obtained to date ( 7 ) . Boussinesq (2) obtained an exact solution for creeping flow past a droplet under the assumptions that interfacial behavior could be described by the Newtonian surface fluid model and that surface tension and the two surface viscosities were independent of position on the phase interface. The results of Boussinesq's analysis do not appear to be in any better agreement with available experimental data than those of Hadamard andNeither the analysis of Boussinesq nor the theory of Hadamard-Rybczynski considers the possible presence of surfactants (materials which have an affinity for a phase interface and which consequently alter the surface tension of a system). In practice it is very difficult to eliminate trace quantities of surface-active materials from an experiment. The observation of a fairly immobile cap on the trailing surface of a droplet ( 8 ) suggests that any surfaceactive agents present are not uniformly distributed around the surface, but rather that they are continuously swept toward the rear of the droplet by the fluid motion. If we express surface stress in terms of surface tension alone, the resultant accumulation of surfactants ...

show abstract

Effects of Surface Active Agents on Extraction from Droplets

Cited by 48 publications

References 10 publications

A new solution to emulsion liquid membrane problems by non‐Newtonian conversion

A new solution to emulsion liquid membrane problems by non‐Newtonian conversion

Semicontinuous emulsion copolymerization of styrene and butyl acrylate

Creeping flow past a fluid globule when a trace of surfactant is present

Contact Info

Product

Resources

About