Mechanistic Study on Surface Tension of Binary and Ternary Mixtures Containing Choline Chloride, Ethylene Glycol and Water (Components of Aqueous Solutions of a Deep Eutectic Solvent, Ethaline)

Abstract

The paper reports the results of the measurement of surface tension in binary liquid mixtures containing choline chloride, ethylene glycol and water and ternary mixtures of ethaline (a eutectic mixture of ethylene glycol and choline chloride, the so-called deep eutectic solvent) with water. The surface tension is determined in a wide range of components’ concentration for the temperatures of 25, 30, 40, 50, 60 and 70 °C. The dependences of surface tension on the concentration of liquids are treated by means of Gibbs adsorption isotherm and linear form of Langmuir adsorption isotherms. The values of the equilibrium constant of adsorption at the interface liquid solution/air as well as the standard adsorption Gibbs energy, enthalpy and entropy are calculated for the binary and ternary mixtures under consideration. The obtained results are interpreted in the light of intermolecular interactions in fluids. Our findings show that ethylene glycol and choline cation interact with each other in the adsorbed surface layer formed at the interface between air and diluted solutions of ethaline.

Intermolecular Interactions of Edaravone in Aqueous Solutions of Ethaline and Glyceline Inferred from Experiments and Quantum Chemistry Computations

“…Further, the addition of D 2 O leads to the formation of ethylene glycol dimers and trimers. On the other hand, the studies on the surface tension of mixtures containing ETA and water showed that choline cation and ethylene glycol form intermolecular interactions in the diluted ethaline/air interface layer [ 35 ]. As can be seen from the above-mentioned examples, the composition and addition of water have a significant effect on the structural features and nature of the interactions occurring in ETA and GLE.…”

Extensive characterization of choline chloride and its solid–liquid equilibrium with water

“…However, its presence in the mixture should be carefully investigated since water might bring structural changes in the DES intermolecular network due to its highly polar nature. 21 The large majority of studies investigating the role of water in DESs are related to mixtures of choline chloride with well-known hydrogen bond donors, such as lactic acid, 7,22 urea, [23][24][25][26][27] glycols, 7,[26][27][28][29][30][31] and sugars. 7 Recently, it was suggested that aqueous solutions of choline chloride, with a certain mole ratio, were also deep eutectic solvents.…”

“…The large majority of studies investigating the role of water in DESs are related to mixtures of choline chloride with well-known hydrogen bond donors, such as lactic acid, 7,22 urea, 23–27 glycols, 7,26–31 and sugars. 7 Recently, it was suggested that aqueous solutions of choline chloride, with a certain mole ratio, were also deep eutectic solvents.…”

Interfacial Properties of Deep Eutectic Solvents by Density Gradient Theory

“…Temperature dependence of surface tension for deep eutectic solvents. Symbols, experimental data. ,,,− Lines, DGT plus PC-SAFT model using parameters from Tables and …”