Retardation factor surfactants

There are two reasons in favour of the theory of the dynamic adsorption layer at weakly and strongly retarded bubble surfaces. At first, the theory has been developed also for large Re, and secondly it was developed for small Re also for the case of surface retardation controlled by surfactant concentration as well as by other retardation factors. 

A retardation factor was calculated from these data and yielded a distribution coefficient Kf) of 0.0017, which corresponds to an adsorption of 0.16 mg of surfactant per gram of soil, but these values are not significantly different from zero taking the experimental error into account. Regardless, these values are lower than those reported by Rouse et al. [45] for other surfactants on similar soils. We attribute this in part to the very favorable characteristics of dihexyl sulfosuccinate and in part to the use of the IPA cosolvent. High values of surfactant retention... 

In contrast to reaction (5-158), addition of micelle-forming surfactants can also slow down chemical reactions. For example, the spontaneous hydrolysis of phenyl chloroformate at 25 °C according to Eq. (5-158a) is retarded by a factor of ca. 16 on addition of sodium dodecylsulfate (SDS) above the one. Below the erne, the SDS... 

Aliphatic and aromatic nucleophilic substitution reactions are also subject to micellar effects, with results consistent with those in other reactions. In the reaction of alkyl halides with CN and S Oj in aqueous media, sodium dodecyl sulfate micelles decreased the second-order rate constants and dodecyltrimethylammonium bromide increased them (Winters, 1965 Bunton, 1968). The reactivity of methyl bromide in the cationic micellar phase was 30 to 50 times that in the bulk phase and was negligible in the anionic micellar phase a nonionic surfactant did not significantly affect the rate constant for n-pentyl bromide with S2O3-. Micellar effects on nucleophilic aromatic substitution reactions follow similar patterns. The reaction of 2, 4-dinitrochlorobenzene or 2, 4-dinitrofluorobenzene with hydroxide ion in aqueous media is catalyzed by cationic surfactants and retarded by sodium dodecyl sulfate (Bunton, 1968, 1969). Cetyltrimethylammonium bromide micelles increased the reactivity of dinitrofluorobenzene 59 times, whereas sodium dodecyl sulfate decreased it by a factor of 2.5 for dinitrochlorobenzene, the figures are 82 and 13 times, respectively. A POE nonionic surfactant had no effect. 

Another difference lies in the role of electric double-layer repulsion, which is often a key factor in stabilizing aqueous foams with ionic surfactants. The adsorption of ionic surfactant at the liquid surface leads to the formation of a charged surface and a diffuse layer of counterions. As the foam lamellae thin because of the drainage of liquid, these counterions begin to repel each other and retard further thinning. Because ionization is not possible in nonpolar solvents, this double-layer mechanism is not operative in nonpolar foams. 

Most acrylic monomers will undo go emulsion polymerisation, although the monomer molecules must be available in a solubilised state, either in the form of surfactant stabilised droplets or in micelles. Where the acrylic monomer contains a long chain alkyl group (e.g. lauiyl and stearyl acrylates and methacrylates) polymerisation may be retarded by steiic factors resulting in low degrees of conversion of the monomer. 

Like all surfactant-related phenomena, surfactant—polymer interactions involve a complex balance of factors encouraging and retarding association and are understandable only if those factors can be reasonably estimated. The complications added by the energetics of polymer conformations in solution only add to the... 

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