CO2 solubility and diffusivity in 1-ethyl-3-methylimidazolium cation-based ionic liquids; isochoric pressure drop approach

In this study, an experimental approach based on the isochoric pressure drop principle was implemented to measure (at low equilibrium pressure, 1.3–3.6 bar) solubility and binary diffusivity of CO2 (constant variable) in four imidazolium-based room-temperature ionic liquids (RTILs), namely, 1-ethyl-3-methylimidazolium acetate ([emim][Ac]), dicyanamide ([emim][DCA]), methyl sulfate ([emim][MeSO4]) ethyl ([emim][EtSO4]). The molar fraction dissolved Henry's law constant were measured from data. Constant diffusion coefficients transient thin-film semi-infinite volume models. original approach, variable coefficient model used concentration-based coefficient. Anion interaction RTILs found have a strong influence solubility, studied anions ranked as [Ac]− >> [EtSO4]− > [DCA]− [MeSO4]−. Increasing temperature is not likely for while it favors diffusivity. Thin-film measurements be more suitable [emim][MeSO4] [emim][EtSO4], [emim][Ac] [emim][DCA]. Variable monotonous function time, which increased early stages decreased after certain time. Gibbs free energy, enthalpy, entropy values indicate strength favorable between RTILs, mildly exothermic nature falling range physisorption.