Physical Properties and NH3 Solubilities of Deep Eutectic Solvents Formed by Choline Chloride and Glycols

Abstract

• Densities and viscosities of ChCl+glycol DESs were measured at 298.2~358.2 K and 101.3 kPa. • Solubilities of NH 3 in ChCl+glycol DESs were measured at 298.2~353.2 K and 0~250.0 kPa. • Effects of temperatures, pressures and liquid compositions on NH 3 solubilities were examined. • Solubilities of NH 3 were fitted to the K-K equation to calculate the thermodynamic parameters. In this study, deep eutectic solvents (DESs) formed by choline chloride (ChCl) and three glycols−ethylene glycol (EG), 1,3-propanediol (PD) and 1,4-butanediol (BD)−were investigated for NH 3 absorption. The densities and viscosities of DESs at 298.2~358.2 K and 101.3 kPa were measured first, and fitted to the linear equation and Vogel−Fulcher−Tammann equation respectively. The solubilities of NH 3 in DESs at 298.2~353.2 K and 0~250.0 kPa were then measured by a well-established dual-chamber method. The effects of temperatures, pressures and liquid compositions on NH 3 solubilities were examined, and the NH 3 solubilities of DESs were compared with those of other solvents reported in the literature. Finally, the solubilities of NH 3 were fitted to the Krichevsky−Kasarnovsky equation to calculate the Henry's constants and partial molar volumes at infinite dilution of NH 3 in DESs, as well as the enthalpy changes, Gibbs free energy changes and entropy changes for NH 3 absorption process.