Thermophysical characterization of the deep eutectic solvent choline chloride:ethylene glycol and one of its mixtures with water

Abstract

The deep eutectic solvent ethaline, containing choline chloride as H-bond acceptor and ethylene glycol as H-bond donor and one of its mixture with water are studied in this work. Ethaline is anhydrous, with a 1:2 mol ratio. Hydrated ethaline, choline chloride:ethylene glycol:water, was studied in a 1:1.98:0.95 mol ratio. Several volumetric, acoustic, optical, thermal, surface, and transport properties were measured and calculated. The working temperature ranges from 278.15 to 338.15 K at pressure = 0.1 MPa. The effects of temperature, water inclusion, and the nature of the donor compound are evaluated. With regard to temperature, the system's behaviour is as expected: a linear relation for the thermodynamic properties and agreement with the Vogel-Fulcher-Tammann equation for the transport properties. The water molecules hardly modify the ethaline structure. The choline chloride – ethylene glycol interactions are weaker than those for choline chloride - glycerol.