Experimental Study on Isobaric Molar Heat Capacities of a Deep Eutectic Solvent: Choline Chloride + Ethylene Glycol

In this study, a flow calorimeter is used to measure the isobaric molar heat capacities (Cp) of one deep eutectic solvent (DES) containing choline chloride and ethylene glycol at different molar ratios. The experiment is performed at temperatures from 313 to 343 K and pressures up to 25 MPa, while the expanded uncertainties of temperature, pressure, molar fraction, and Cp are estimated to be lower than 0.02 K, 5.0 kPa, 1.4 × 10–4, and 1.28%, respectively. The results show that Cp change linearly with temperature, while it is almost constant with a variety of pressure. A quadratic relation between Cp and molar fraction of ethylene glycol is observed, which shows a decreasing tendency with the increase of molar fraction. A correlation for the Cp of the chosen DES and pure ethylene glycol is proposed for a better application of the data.