Solubilization of n-Alkylbenzenes into Gemini Surfactant Micelles in Aqueous Medium

Abstract

Solubilization of benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene into micelles of decanediyl-1-10-bis(dimethyltetradecylammonium bromide) (14-10-14,2Br(-)) has been investigated in the temperature range from 288.2 to 308.2 K. The equilibrium concentrations of all the solubilizates are determined spectrophotometrically. The concentration of the solubilizates remains constant below the critical micelle concentration (cmc) and increases linearly with an increase in 14-10-14,2Br(-) concentration above the cmc. Compared to the mother micelle, the solubilized micelles indicate much larger hydrodynamic diameters, which are determined by dynamic light scattering. Therefore, the Gibbs energy change for the solubilization of n-alkylbenzenes has been evaluated by the partitioning of the solubilizates between the aqueous and micellar phases. Furthermore, the enthalpy and entropy changes for the solubilization could be calculated from temperature dependence of the Gibbs energy change. From the thermodynamic parameters, it is found that the solubilization for the present system is entropy-driven and that the location of the solubilizates moves into the inner core of the micelle with an elongation of their alkyl chains. The movement on the location is also supported by the results of absorption spectra, Fourier transform infrared (FTIR) spectra, and two-dimensional nuclear Overhauser effect spectroscopy (2-D NOESY).

A theoretical investigation of the influence of the second critical micelle concentration on the solubilization capacity of surfactant micelles

“…Comprehensive experimental systematic studies of the solubilization of long-chain hydrophobic components by gemini surfactant micelles are, unfortunately, still missing and experimental evidence of the role of spacer group length is, to our knowledge, not yet available. [43][44][45][46][47] …”

Basic polymerized imidazolide-based ionic liquid: an efficient catalyst for aqueous Knoevenagel condensation

“…For practical use and application, a surfactant with low CMC is often considered to play an efficient role in solubilization [ 28 ] . Moreover, the CMC of BPIL-1% ， condensation, organic substances molecules diffused to the aqueous-organic interface and their aqueous solubility increased via their incorporation into micelles in surfactants solution [29 ] , which contributed to the interaction of reactants with catalytic centers. Consequently, BPIL showed higher catalytic activity 10 than NaOH.…”

Solubilization of Progesterone and its Derivatives into Gemini Surfactant Solutions

“…∆G 0 means the Gibbs energy change for transfer of the solubilizate molecules from phase W to phase A. This is calculated according to the partition equilibrium, where the aggregate including the solubilizates is regarded as a separate phase 12,18,20 . The changes of enthalpy ∆H 0 and entropy ∆S 0 for the transfer can be evaluated by the following equations.…”

“…Commonly, nonionic surfactant solutions exhibit a much lower critical micelle concentration cmc and are therefore used as efficient solubilizers in various fields of industry. We have investigated the solubilization of poorly soluble substances using gemini surfactant solutions 11,12 . Gemini surfactants are a dimer of typical surfactants in which the surfactant molecules are linked by a spacer.…”