Solubility of p-Nitroaniline in Supercritical Carbon Dioxide with and without Mixed Cosolvents

Using the dynamic-flow method, the solubility of p-nitroaniline in supercritical carbon dioxide was measured with and without mixed cosolvents at pressures of (11.0, 13.0, 15.0, 18.0, and 21.0) MPa, and in the temperature range of (308 to 328) K. The effects of cosolvents (ethanol + n-hexane (molar ratio of 1:1), ethanol, and n-hexane) were studied at a concentration of 4.0 mol %. The solubility of p-nitroaniline showed that it could be a slightly enhanced by n-hexane but decreased by ethanol and the mixed cosolvent. The data of p-nitroaniline in pure SCCO2 were successfully correlated by Chrastil, Mendez-Santiago and Teja (MST), Bartle, and Kumar and Johnston (K-J) models, while the experimental ones with different cosolvents were calculated by modified Chrastil, modified MST, Sovova,and modified Sovova models. All the correlation results were relatively satisfactory with the experiments.