Levulinic Acid Solubility in Supercritical Carbon Dioxide with and without Ethanol as Cosolvent at Different Temperatures

The solubility of levulinic acid in supercritical carbon dioxide in the absence and presence of ethanol (mole fraction of ethanol x(3) = 0.0, 0.027, and 0.051) as a cosolvent was measured with a synthetic method at temperatures from (313.0 to 342.4) K and pressures from (8.0 to 19.0) MPa. It is demonstrated that, at a fixed temperature, the solubility of levulinic acid increases with increasing pressure; at a fixed pressure, it decreases with increasing temperature. When ethanol is added into supercritical carbon dioxide as a cosolvent, the solubility of levulinic acid increases greatly, and it increases with the concentration of the added ethanol. The experimental solubility data can be correlated using the Chrastil model and a modified Chrastil model with four adjustable parameters.