Sodium dodecylbenzenesulfonate, micelle

The CMC for sodium dodecylbenzenesulfonate is about lO Af at 25°C. Calculate K for the preceding reaction, assuming that it is the only process that occurs in micelle formation. Calculate enough points to make your own quantitative plot corresponding to Fig. Xni-13. Include in your graph a plot of (Na )(R ). Note It is worthwhile to invest the time for a little reflection on how to proceed before launching into your calculation ... 

Molecular Weight b Critical Micelle Concentration sodium dodecylsulfate d sodium dodecylbenzenesulfonate... 

The electrochemical behavior of ascorbic acid (1) and uric acid (3) in the presence of micelles and their selective determination were investigated. Aqueous cetylpyridinium bromide (cpb) and sodium dodecylbenzenesulfonate (sdbs) miceUar solutions have been used. The oxidation peak potentials for 1 and 3 are separated by 270 mV in the presence of cpb in aqueous phosphate buffer solution (pH 6.8), thus allowing their selective determination, as well as the selective determination of 3 in the presence of excess of 1. The method is simple, inexpensive and rapid with no need to modify the electrode surface by tedious procedures, and it was applied to 3 determination in samples of human urine and serum. Abnormal levels of uric acid in urine and serum are symptomatic of several diseases (gout, hyperuricaemia and Lesch-Nyhan syndrome) . 

FIG. 2.7 Relevant length scales for the colloidal structure of worm-like micelles contour length, Lc, entanglement length, /e, mesh size, m, persistence length, Zp and cross-sectional radius, rcs. Values shown are those measured for a solution with 1.5% total surfactant at a cetyltrimethylammonium tosylate (CTAT)/sodium dodecylbenzenesulfonate (SDBS) ratio of 97/3 with 0.10% added sodium tosylate. (Reproduced from Schubert, B.A., Kaler, E.W., and Wagner, N.J., Langmuir, 19, 4079 -089, 2003. With permission.)... 

Anionic Surfactants onto Kaolinite and lUite. In the investigation of the adsorption of sodium dodecylbenzenesulfonate (SDBS) and sodium dodecyl sulfate (SDS) onto asphalt covered kaolinite and illite surfaces, Siffert et al. [5S] observed Langmuir type I isotherms for SDS adsorption onto Na kaolinite and Na illite while the SDBS exhibited a maximum in adsorption with a decrease beginning near the CMC. Adsorption maxima were observed near the CMC for both surfactants in the Ca kaolinite and Ca illite systems. The adsorption behavior was explained as precipitation of the calcium salt of the surfactants (an idea supported by other studies), and the interaction of the aromatic ring in SDBS with the asphalt. This interaction favors desorption of the asphalt rather than adsorption of the SDBS. The amount of asphalt desorbed by SDBS was twice that desorbed by SDS. Other explanations for adsorption maxima include mixed micelle formation [55] and electrostatic repulsion of micelles from the bdayer covered surface [59]. 

Spinel ferrites can be synthesized in microemulsions and inverse micelles. For example, MnFejO nanoparticles with controllable sizes from about 4-15 nm are synthesized through the formation of water-in-toluene inverse micelles with sodium dodecylbenzenesulfonate (NaDBS) as suifactanP. This synthesis starts with a clear aqueous solution consisting of Mn(N03)2 and Fe(NOj)j. A NaDBS aqueous solution is added to the metal salt solution, subsequent addition of a large volume of toluene forms reverse micelles. The volume ratio of water and toluene determines the size of the resulting MoFCjO nanoparticles. 

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