Solubility of three hydroxycinnamic acids in supercritical carbon dioxide

Abstract

The solubility of three trans-hydroxycinnamic acids, 4-hydroxycinnamic acid ( p-coumaric acid), 3,4-dihydroxycinnamic acid (caffeic acid), and 4-hydroxy-3-methoxycinnamic acid (ferulic acid), in supercritical carbon dioxide (SC-CO 2) has been determined at different pressures up to 50 MPa and temperatures from 313 to 333 K. These hydroxycinnamic acids are phenolic compounds contained in grape seeds and other natural substrates, and the data presented in this work are valuable to know the possibility of their separation from such natural matrices by extraction with SC-CO 2. Experimental data have been modeled by using the Peng–Robinson equation of state (PR-EOS) to determine the fugacities of the fluid phase. Two semiempirical density dependent correlations have also been used for data correlation, specifically, the Chrastil model, and a model that assumes a linear correlation between the enhancement factor and the density of the solvent.