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 (C_p) 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 C_p are estimated to be lower than 0.02 K, 5.0 kPa, 1.4 × 10^–4, and 1.28%, respectively. The results show that C_p change linearly with temperature, while it is almost constant with a variety of pressure. A quadratic relation between C_p and molar fraction of ethylene glycol is observed, which shows a decreasing tendency with the increase of molar fraction. A correlation for the C_p of the chosen DES and pure ethylene glycol is proposed for a better application of the data.