Measurement and mathematical modeling of solubility of buttery-odor substance (acetoin) in supercritical CO2 at several pressures and temperatures

• New solubility data of buttery-odor substance (acetoin) in supercritical CO2 was reported.
• The solubility measurements were conducted at wide range of pressures and temperatures.
• Correlation of solubility data by Chrastil and Del Valle and Aguilera density-based models.
• Phase equilibria were evaluated by cubic equation of state incorporated with mixing rules.
• Satisfactory agreement between actual and predicted solubilities over the measurement range.

The solubilities of acetoin (3-hydroxy-2-butanone), a frequently used buttery-odor compound in supercritical carbon dioxide (SC-CO2) at several pressures and temperatures were measured in this work. The measurements were conducted in a static-analytic mode at several pressures ranging from 8 MPa to 28 MPa and four temperatures of 313.15 K, 323.15 K, 333.15 K, and 343.15 K. The equilibrium was established for 3–4 h. The solubilities of acetoin in SC-CO2 increased with increasing both pressure and temperature beyond the crossover pressure at 8 MPa. Two density-based models namely Chrastil and Del Valle-Aguilera and Peng–Robinson equation of state (PR-EOS) with quadratic and Stryjek–Vera mixing rules were used to represent experimental solubilities and to describe phase behavior of the system. Both Chrastil and Del Valle-Aguilera models were able to correlate experimental solubility data satisfactorily with absolute average relative deviation (AARD) of 0.27%. Similarly, the phase equilibrium behavior of acetoin + supercritical CO2 binary system can be well interpreted by PR-EOS with quadratic (AARD of 0.11%) and Stryjek–Vera mixing rules (AARD of 0.08%).

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