Separation Performance of Ethaline: Infinite Dilution Activity Coefficients and the Excess Thermodynamic Properties

Abstract

This paper presents excess thermodynamic data of a mixture of choline chloride, a hydrogen bond acceptor (HBA), and ethylene glycol, a hydrogen bond donor (HBD), with a molar ratio of 1:2, correspondingly. This mixture is popularly known as ethaline. A gas−liquid chromatograph (GLC) fitted with a thermal conductivity detector (TCD) was used to determine infinite dilution activity coefficient (IDAC) values of different functional groups (e.g., alkanes, alkenes, alkynes, cycloalkanes, aromatics, alcohols, ketones, and water) for 32 different organic solutes at different temperatures (T = 313.15−343.15 K) and air pressures. The partial excess molar properties, including Gibbs free energy, enthalpy, and entropy, were computed from the infinite dilution activity coefficient measurements at T = 323.15 K. Furthermore, the separation performance of common separation problems, i.e., hexane/ benzene, cyclohexane/hexane, ethanol/toluene, and acetone/methanol, was evaluated through the selectivity and capacity values, and this was also computed from the infinite dilution activity coefficient values. It was found that ethaline could not be suitable for prospective separation issues, as a result of the poor thermodynamic data that were measured.