Solubilities of Carbon Dioxide in 1-Ethyl-3-methylimidazolium Thiocyanate, 1-Ethyl-3-methylimidazolium Dicyanamide, and 1-Ethyl-3-methylimidazolium Tricyanomethanide at (298.2 to 373.2) K and (0 to 300.0) kPa

The solubilities of carbon dioxide (CO2) in three low-viscous ionic liquids (ILs)—1-ethyl-3-methylimidazolium thiocyanate ([emim][SCN]), 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]), and 1-ethyl-3-methylimidazolium tricyanomethanide ([emim][TCM])—were determined by volumetric method at the temperature range of (298.0 to 373.2) K and pressure range of (0 to 300.0) kPa, which are relevant to the capture of CO2 from flue gas and natural gas. The Henry's law constants and partial molar volume at infinite dilution of CO2 in the three ILs were calculated by fitting the solubility data with the Krichevsky–Kasarnovsky (K-K) model. The absorption enthalpies, Gibbs free energy changes, and absorption entropies of CO2 in the three ILs were also calculated based on the dependence of Henry's constants on temperature. DFT calculations were further performed to better understand the interaction of ILs with CO2 on the molecular level and provide theoretical basis for the different CO2 solubilities in the three ILs.