Exploration of the soluting-out effect of carbohydrates on the micellization and surface activity of long-chain imidazolium ionic liquid in the aqueous medium

In order to elucidate the role of polyhydroxy compounds (PHC) in modifying the micellization and interfacial behaviour of surface-active ionic liquids (SAILs), system consisting of 1-tetradecyl-3-methylimidazolium bromide ([C(14)mim][Br]) in water and in aqueous solutions of D(+)-Xylose and D(+)-Glucose as additives at (298.15, 303.15 and 308.15) K using specific conductance, UV-visible spectroscopy, FT-IR spectroscopy, surface tension measurement was investigated. From the electrical conductivity measurements, various parameters such as critical micelle concentration (CMC), degree of ionization of the counterion on the micelles (alpha), the standard Gibbs energy of micellization (Delta G(m)(o)), etc. have been evaluated for different concentrations of carbohydrates at different temperatures. FT-IR spectroscopy is utilized to record the structural changes occurring in the studied systems at below CMC, at CMC, and above CMC concentrations. The various surface parameters including CMC, surface tension at CMC (gamma(cmc)), surface pressure at the interface (Pi(cmc)), the maximum surface excess concentration (Gamma(max)), and the minimum area per surfactant molecule at the surface, A(min) have also been obtained using surface tension measurements. The results obtained indicated that the CMC value of the IL in the presence of different concentrations of carbohydrates decreases in the order; D(+)-Glucose > D(+)-Xylose demonstrating that carbohydrates have a soluting-out effect and their tendency to lower the CMC value of IL increases with an increase of hydro-philicity of carbohydrates. (C) 2020 Elsevier B.V. All rights reserved.