Diffusion coefficients of carbon dioxide-ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) system at temperatures of 313 K and 323 K and pressures of 5 MPa and 8 MPa

This work reports the mutual diffusion coefficients of carbon dioxide - 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) system at different temperatures (313.15 and 323.15 K) and pressures (5 and 8 MPa). We have determined the time-dependent solubility of carbon dioxide in the ionic liquid and then, fit a computational fluid dynamics (CFD) model to the experimental data to obtain the diffusion coefficients. The increase in the molar density and the expansion of the liquid phase during the dissolution of carbon dioxide are taken into account in the transport model. The results show that the mutual diffusion coefficients increase with carbon dioxide mole fraction and the values obtained at thermodynamic phase equilibrium compare well with those calculated using different correlations.