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The interaction of phenoxide anion with several cationic surfactant micelles (DTAB, TTAB, CTAB, CDEAB, and CTAC) was studied by UV/Vis spectrophotometric method. The solubilization constants of phenoxide anion into the cationic micellar phase and the critical micelle concentration of these surfactants in the presence of the phenoxide anion could be determined from the absorbance changes. The measured solubilization constants were changed according to the following order: Ks(CTAC)>Ks(CDEAB)>Ks(CTAB)>Ks(TTAB)>Ks(DTAB). Effects of salts(NaCl and NaBr) and n-alcohols(butanol, pentanol, and hexanol) on the solubilization of phenoxide anion by the TTAB system have been also measured and analyzed. There was a great decrease of solubilization constant and CMC with these additives. The standard Gibbs free energy, enthalpy, and entropy changes for the solubilization of phenoxide anion by the TTAB system were calculated from the temperature dependence of Ks values.
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