The Solubility Parameter of Carbon Dioxide and Its Solubility in Ionic Liquids

Carbon dioxide as a solute interacts with solvents mainly via dispersion forces. Its Hildebrand solubility parameter, δH, may therefore be used to predict its dissolution. The usual definition of δH, involving ΔvH, the molar enthalpy of vaporization, is inapplicable for carbon dioxide, it being a gas at the temperatures of technical interest (298 ≤ T/K ≤ 333). The ability of CO2 to accept hydrogen bonds from donor solvents and its appreciable polarizability justify the determination of its Hansen solubility parameters. The definite equation of state of CO2 reported by Span and Wagner permits the determination of the required parameters. The solubility of gaseous carbon dioxide in ionic liquids (room temperature ionic liquids and deep eutectic solvents) has been extensively studied and is discussed in the light of the above statements.