• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.250-259
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• 2020

The solubilization constant (K_s) was determined by the UV-Vis method to investigate the interaction between organic matter (solubilized substance) and surfactant in solubilization. Solubilization constants and thermodynamic functions, according to the hydrophobic interaction between organic mater (4-alkylanilines with different alkyl substituent length) and cationic surfactants (DTAB, TTAB, and CTAB, having different hydrophobic lengths), were measured and calculated at various temperatures and compared with each other. As a result, the hydrophobic interactions between organic matters and cationic micelles increased with increasing the chain length of solute's substituent as well as surfactant's hydrophobe. However, the hydrophobic effect by the alkyl substituent of organic matter was greater than the hydrophobic effect by the surfactant. In addition, the results of the calculated thermodynamic functions showed that 4-alkylaniline was solubilized at the deep place in the micelle and its solubilization was greatly dependent on both the hydrophobic effects of organic matter and surfactant. At the calculated iso-structural temperature, the difference between the maximum and minimum values was less than 1K within the experimental conditions.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1143-1152
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• 2019

In order to study the solubilization of aniline by cationic surfactants (DTAB, TTAB and CTAB), the solubilization constant (K_s) and thermodynamic functions were measured and calculated by using the UV-Vis method. The solubilization constants of aniline with the change of temperature were measured, and the effects of addition of ionic salts and organics on the solubilization constants were investigated. These effects of additives and temperature changes were compared and analyzed for each type of surfactant, and the solubilization of aniline was analyzed microscopically by comparing and evaluating the thermodynamic functions obtained from the solubilization constants. As a result, the Gibbs free energy and enthalpy changes were both negative and the entropy changes were positive within the measured range for the solubilization of aniline by cationic surfactants. The solubilization constant value decreased with increasing temperature and increased with increasing carbon chain length of the surfactant. As the concentration of ionic salts increased, the Gibbs free energy change increased at first and then decreased. In n-butanol solution, the Gibbs free energy change tended to increase continuously with increasing the concentration of n-butanol.

• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.438-447
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• 2020

The critical micelle concentration (CMC) values of the mixed surfactant systems and the solubilization conatant (K_s) values of 4-ethylaniline in those solutions were measured and analyzed by the UV-Vis method. As a result, the mixed surfactant systems of TTAB/LSB and TTAB/TX-100 did not deviate significantly from ideal mixed micellization. However, the mixed systems of SDS/LSB and SDS/TX-100 showed great negative deviations from ideal mixed model. These differences showed that the intensity of the interaction between two components in the mixed micelle was different for each mixed system and that these differences greatly influenced the solubilization of 4-ethylaniline by a mixed surfactant system. Among pure surfactants, an anionic surfactant such as SDS showed a greater K_s value than other ionic surfactants, and the K_s value by each surfactant system decreased in the order of SDS≫TTAB≧LSB>TX-100. In addition, the K_s values of all the mixed surfactant systems were higher than those of the pure surfactants constituting the mixed systems.