The effect of water on the thermal conductivities of deep eutectic solvents (choline chloride + ethylene glycol) using two-wire structure 3ω method

The advantages of deep eutectic solvent (DES), such as non-toxic, non-flammable, low vapor pressure and low cost, make it a green solvent for capturing carbon dioxide. Adding water can change the nanostructures of DES and thus significantly influent the physical and chemical properties. At present, most researches focus on the theoretical study while few experimental studies on the effect of water on the thermal conductivity of DES. In this paper, the 3ω experimental system was improved using a two-wire structure to eliminate the end effect and measured the thermal conductivities of the DES composed of choline chloride and ethylene glycol and its aqueous solution to study the effect of water on the thermal conductivities. The uncertainty of thermal conductivity is less than 4%. The second-order Scheffé polynomial was modified to make it more suitable for fitting the thermal conductivities of the mixtures containing DES. The average absolute relative deviation calculated by the equation is 2.16%, which corroborates the high accuracy of the improved equation.