Solubility and thermodynamic properties of NH3 in choline chloride-based deep eutectic solvents

Abstract

Deep eutectic solvents (DESs), derived from the mixtures of two or more hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), were extensively reported as gas absorbents. In this work, four kinds of DESs were prepared from choline chloride (HBA) and glycerol, ethylene glycol, N-methylurea, and trifluoroacetamide. The molar ratio was fixed at 1:2 of choline chloride to HBD. New experimental results were reported for the solubility of NH3 in these DES over the temperature range of (303.15–333.15) K and pressures up to 580 kPa using isochoric saturation method. The molarity of NH3 in the DESs ranges up to 16.27 mol.kg−1. The dependence of the NH3 solubility in the DESs on temperature and pressure were accurately represented by Henry’s law model. Standard Gibbs energy, dissolution enthalpy and dissolution entropy were further deduced from Henry’s law constant of NH3 in the DESs.