Coalescence of bubbles and stability of foams in aqueous solutions of Tween surfactants

Samanta, Sayantan; Ghosh, Pallab

doi:10.1016/j.cherd.2011.04.006

Cited by 73 publications

(39 citation statements)

References 38 publications

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“…The results from the above analysis are shown for the nonionic surfactants in the first four rows in Table 1, along with representative results from literature [41][42][43][44][45][46][47][48][49][50][51][52][53]. One sees that our results are in a relatively good agreement with the literature results with respect to all characteristics studied -CMC, surface tension at CMC, surfactant adsorption at CMC, and average excluded area per molecule.…”

Section: Surface Tension Isothermssupporting

confidence: 84%

Foamability of aqueous solutions: Role of surfactant type and concentration

Petkova

Tcholakova

Chenkova

et al. 2020

Advances in Colloid and Interface Science

147

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In this paper we study the main surface characteristics which control the foamability of solutions of various surfactants. Systematic series of experiments with anionic, cationic and nonionic surfactants with different head groups and chain lengths are performed in a wide concentration range, from 0.001 mM to 100 mM. The electrolyte (NaCl) concentration is also varied from 0 up to 100 mM. For all surfactants studied, three regions in the dependence of the foamability, V A , on the logarithm of surfactant concentration, lgC S , are observed. In Region 1, V A is very low and depends weakly on C S . In Region 2, V A increases steeply with C S . In Region 3, V A reaches a plateau. To analyse these results, the dynamic and equilibrium surface tensions of the foamed solutions are measured. A key new element in our interpretation of the foaming data is that we use the surface tension measurements to determine the dependence of the main surface properties (surfactant adsorption, surface coverage and surface elasticity) on the surface age of the bubbles. In this way we interpret the results from the foaming tests by considering the properties of the dynamic adsorption layers, formed during foaming. The performed analysis reveals a large qualitative difference between the nonionic and ionic surfactants with respect to their foaming profiles. The data for the nonionic and ionic surfactants merge around two master curves when plotted as a function of the surface coverage, the surface mobility factor, or the Gibbs elasticity of the dynamic adsorption layers. This difference between the ionic and nonionic surfactants is explained with the important contribution of the electrostatic repulsion between the foam film surfaces for the ionic surfactants which stabilizes the dynamic foam films even at moderate surface coverage and at relatively high ionic strength (up to 100 mM). In contrast, the films formed from solutions of nonionic surfactants are stabilized via steric repulsion which becomes sufficiently high to prevent bubble coalescence only at rather high surface coverage (> 90 %) which corresponds to related high Gibbs elasticity (> 150 mN/m) and low surface mobility of the dynamic adsorption layers. Mechanistic explanations of all observed trends are provided and some important similarities and differences with the process of emulsification are outlined.

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Section: Surface Tension Isothermssupporting

confidence: 84%

Foamability of aqueous solutions: Role of surfactant type and concentration

Petkova

Tcholakova

Chenkova

et al. 2020

Advances in Colloid and Interface Science

147

View full text Add to dashboard Cite

show abstract

“…When the surfactant concentration increased from nearly 0 to 0.04 mM/m 3 , the swimming velocity of the cells doubled from 150 µm/s to 350 µm/s even though we did not observe any change in the swimming velocity inside the medium as we added the surfactant. We note that the critical micelle concentration (CMC) of Tween 20 in pure water is 0.06 mM/m 3 [18]. The cells' behavior thus changed dramatically, when the surfactant concentration reached the CMC condition.…”

Section: Resultsmentioning

confidence: 88%

Entrapment of Ciliates at the Water-Air Interface

et al. 2013

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The importance of water-air interfaces (WAI) on microorganism activities has been recognized by many researchers. In this paper, we report a novel phenomenon: the entrapment of ciliates Tetrahymena at the WAI. We first characterized the behavior of cells at the interface and showed that the cells' swimming velocity was considerably reduced at the WAI. To verify the possible causes of the entrapment, we investigated the effects of positive chemotaxis for oxygen, negative geotaxis and surface properties. Even though the taxes were still effective, the entrapment phenomenon was not dependent on the physiological conditions, but was instead affected by the physical properties at the interface. This knowledge is useful for a better understanding of the physiology of microorganisms at interfaces in nature and in industry.

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“…The concentration of Tween 80 was 0.15 v/v% which is lower than its critical micellar concentration-CMC (0.012 mol/m 3 $0.1536% v/v) 24 and allows to consider that no micelles are present in our samples.…”

Section: A Materials and Methodsmentioning

confidence: 99%

Enhanced fluorescence emitted by microdroplets containing organic dye emulsions

et al. 2015

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In this paper, laser beam resonant interaction with pendant microdroplets that are seeded with a laser dye (Rhodamine 6G (Rh6G)) water solution or oily Vitamin A emulsion with Rhodamine 6G solution in water is investigated through fluorescence spectra analysis. The excitation is made with the second harmonic generated beam emitted by a pulsed Nd:YAG laser system at 532 nm. The pendant microdroplets containing emulsion exhibit an enhanced fluorescence signal. This effect can be explained as being due to the scattering of light by the sub-micrometric drops of oily Vitamin A in emulsion and by the spherical geometry of the pendant droplet. The droplet acts as an optical resonator amplifying the fluorescence signal with the possibility of producing lasing effect. Here, we also investigate how Rhodamine 6G concentration, pumping laser beam energies and number of pumping laser pulses influence the fluorescence behavior. The results can be useful in optical imaging, since they can lead to the use of smaller quantities of fluorescent dyes to obtain results with the same quality.

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Coalescence of bubbles and stability of foams in aqueous solutions of Tween surfactants

Cited by 73 publications

References 38 publications

Foamability of aqueous solutions: Role of surfactant type and concentration

Foamability of aqueous solutions: Role of surfactant type and concentration

Entrapment of Ciliates at the Water-Air Interface

Enhanced fluorescence emitted by microdroplets containing organic dye emulsions

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