Investigation of solubilities of carbon dioxide in five levulinic acid-based deep eutectic solvents and their thermodynamic properties

• Solubilities of CO2 in five levulinic acid-based DESs were reported.
• The experimental data were well correlated by Henry’s law.
• The dissolution Gibbs free energy, enthalpy, and entropy changes were derived.
• The dissolving ability of CO2 with the structure of DESs was analyzed.
• The performances of present DESs and other solvents were compared.

Solubilities of CO2 have been determined in five deep eutectic solvents (DESs) at temperatures (303.15–333.15) K with 10 K intervals under a pressure of (0–600.0) kPa using isochoric saturation method. These DESs were prepared from levulinic acid (LA) and quaternary ammonium salt (acetylcholine chloride, ACC; tetraethylammonium chloride, TEAC; tetraethylammonium bromide, TEAB; tetrabutylammonium chloride, TBAC; and tetrabutylammonium bromide, TBAB) with the mole ratio of 3:1. Henry’s constants and thermodynamic properties such as Gibbs energy, enthalpy and entropy of dissolution were deduced by correlating the solubility data. Results demonstrated that the solubility of CO2 in DESs increased with the increasing pressure or the decreasing temperature. The enthalpies of dissolution were all exothermal in each condition. The Henry’s law constants based on mole fraction and molality of CO2 in DESs vary from (12.30 to 28.66) MPa and (1.79 to 3.94) MPa, respectively.