Physicochemical Studies on the Micellization of Cationic, Anionic, and Nonionic Surfactants in Water鈥揚olar Organic Solvent Mixtures

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• 作者：Sibani Das ; Satyajit Mondal ; Soumen Ghosh
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2013
• 出版时间：September 12, 2013
• 年：2013
• 卷：58
• 期：9
• 页码：2586-2595
• 全文大小：394K
• 年卷期：v.58,no.9(September 12, 2013)
• ISSN：1520-5134

文摘

The effect of cosolvent (ethane-1,2-diol and dimethyl sulfoxide) on the self-assembly of three surfactants, N,N,N-trimethyl-1-dodecanaminium bromide (DTAB), sodium [dodecanoyl(methyl)amino]acetate (SDDS), and polyoxyethylene (20) sorbitan monolaurate (Tween-20) in aqueous solution have been investigated by conductometric, tensiometric, and viscometric techniques at 298 K. The main focus was on the effect of solvent on critical micelle concentration (cmc), free energy contribution to micellization (螖G_m⁰), tail transfer Gibbs free energy (螖G_trans⁰), Gibbs adsorption energy (螖G_ads⁰), and some micellar interfacial parameters, for example, Gibbs surface excess (螕_max), minimum area per surfactant molecule (A_min), surface pressure (螤_cmc), and pC₂₀(= 鈭抣og(C₂₀), where C₂₀ is the surfactant molar concentration required to reduce the surface tension of mixed solvent by 20 mN m^鈥?). With increasing concentration of cosolvent in the binary mixture, the cohesive force decreases, and surfactant molecules are more soluble in mixed solvent. As a result, micellization process becomes less favorable, and an increase in cmc was obtained. Steady state fluorescence spectroscopy was used to determine the aggregation number (N_agg) of the surfactants in organic solvent鈥搘ater binary mixture and also the micropolarity of the mixed solvent. It was observed that N_agg decreased with the increase of organic solvent concentration. The micropolarity of the mixed solvent and packing parameter (P) were also determined.