Solubility of carbon dioxide in dimethylsulfoxide and N-methyl-2-pyrrolidone at elevated pressure

Experimental data on the solubility of CO2 in dimethylsulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) are reported at temperatures of 298, 308 and 318 K and pressures approaching the mixture critical point for each binary system. The corresponding volumetric expansions of DMSO and NMP with CO2 are also presented. The solubility data are correlated with the Peng–Robinson equation of state (PR-EOS). At a given temperature and pressure, higher solubilities of CO2 are obtained in NMP compared with DMSO and this trend is consistent with the volumetric expansions of the solvents. A plot of the volumetric expansion data as a function of the solubility of CO2 in the liquid phase suggests that it is unlikely, as a general rule, that the expansion isotherms for the various systems collapse onto a single expansion curve. The existence of a single expansion curve appears to hold only for a given binary system over a limited range of temperature. The use of two adjustable binary interaction parameters with the PR-EOS provides a superior correlation of the liquid phase composition in comparison with the standard PR-EOS, particularly in the vicinity of the mixture critical point.