Solubilities of Carbon Dioxide in Eutectic Mixtures of Choline Chloride and Dihydric Alcohols

Abstract

The solubilities of CO 2 in eutectic mixtures containing choline chloride and dihydric alcohols (including 1,4-butanediol, 2,3-butanediol, and 1,2propanediol) with a molar ratio of choline chloride to dihydric alcohol of 1:3 and 1:4 were measured at 293.15 K, 303.15 K, 313.15 K, and 323.15 K under pressures up to 600.0 kPa using an isochoric saturation method. Henry's constant and the dissolution Gibbs free energy, enthalpy, and entropy changes of CO 2 solvation were obtained by correlating the experimental data. The solubility of CO 2 in the mixtures increased linearly with the increasing pressure or the decreasing temperature. The enthalpies of solution were negative at all conditions.

Solubilities of carbon dioxide in the eutectic mixture of levulinic acid (or furfuryl alcohol) and choline chloride

“…As shown in table 5, values of the solubility of CO 2 in the DESs studied are higher than those in the ammonium-based ILs [48], such as 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium lactate ([hhemel]) and 2-hydroxy-N-(2-hydroxyethyl)-Nmethylethanaminium acetate ([hhemea]), but slightly lower than those in the imidazolium ILs [49][50][51] . Moreover, values of the solubility of CO 2 in DESs are higher than those in dihydric alcohols (or lactic acid) and choline chloride [38,12], but lower than those in urea (or glycerol) and choline chloride [34,37,52]. These differences of the solubility demonstrate that the interactions between the groups in HBDs (with the exception of glycerol) and CO 2 follow the sequence of amide > carbonyl group > ether bond > hydroxyl group.…”

“…A stainless apparatus as illustrated in our previous work [38] was used to measure the solubility of CO 2 in the DESs. It was mainly composed of gas equilibrium cell (EC) and gas reservoir (GR) with the volumes of (141.61 and 370.99) cm 3 , respectively.…”

“…The detailed experimental procedures were described in our previous works [38,39]. In a typical run, the temperature of GR was kept at 303.15 K. After a known mass of DES (about 60 to 80 g, the accurate mass of the DES, w, was weighted by electronic balance) was added into the EC, the air in the whole system was evacuated to pressure p 0 .…”

“…Three thermodynamic properties can be calculated from the correlation of Henry's law constants as following, 1.06 n CC :n urea = 1:2.5 [37] 1.37 n CC :n urea = 1:2 [34] 1.29 n CC :n glycerol = 1:2 [49] 1.70 n CC :n ethylene glycol = 1:2 [35] 2.71 n CC :n lactic acid = 1:2 [12] 4.00 n CC : n 2,3-butanediol = 1:4 [38] 3.44 n CC : n 1,4-butanediol = 1:4 [38] 4.18 n CC :n 1,2-propanediol = 1:4 [38] 4.43 n levulinic acid : n choline chloride = 3:1 2.62 n levulinic acid : n choline chloride = 4:1 2.41 n levulinic acid : n choline chloride = 5:1 2.35 n furfuryl alcohol : n choline chloride = 3:1 3.54 n furfuryl alcohol : n choline chloride = 4:1 3.14 n furfuryl alcohol : n choline chloride = 5:1 2.91 a The standard uncertainty of mole ratio of levulinic acid or furfuryl alcohol to choline chloride is 0.001. Under all conditions, the values of D dis H o are negative, meaning that the absorption of CO 2 in DESs is exothermic and the intermolecular interaction of CO 2 with DESs is strong.…”

“…15, 323.15, and 333.15) K under pressures up to 13 MPa. In our previous works [38,39], the solubility of CO 2 in the DESs composed of choline chloride and HBDs like phenol, 1,4-butanediol, 2,3-butanediol, 1,2-propanediol, diethylene glycol, and triethylene glycol were determined. As a continuation of our study, we will present new measurements on the solubility of CO 2 in the renewable DESs containing levulinic acid (or furfuryl alcohol) and choline chloride at temperatures (303.…”