Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 +- 0.03) kg*m-3 (T = 323.15 K, p = 8.5 MPa) to (147 +- 0.2) kg*m-3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 +- 0.1) kg*m-3 (T = 333.15 K, p = 10.0 MPa), while the highest solute concentration was (151 +- 2) kg*m-3 (T = 333.15 K, p = 26.7 MPa). Additionally, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil s equation and other density-based models was evaluated for each fatty acid.