Solubilities of benzoin, propyl 4-hydroxybenzoate and mandelic acid in supercritical carbon dioxide

A semi-flow type apparatus was used to measure the equilibrium solubilities of benzoin, propyl 4-hydroxybenzoate, and mandelic acid in supercritical carbon dioxide at 308.15, 318.15, and 328.15K over the pressure range from 9 to 24MPa. New equilibrium data of solid solubility in supercritical carbon dioxide are presented. The approach to solid-fluid phase equilibrium is examined based on a plug flow fluid-solid mass transfer model. The Soave-Redlich-Kwong and the Peng-Robinson equations of state (EOS), with the van der Waals and the Huron-Vidal type mixing rules were used to correlate the experimental data. The solid solubility data were also correlated with density based semi-empirical equations of Chrastil, and Santiago-Teja. It is shown that these solid solubility data are correlated with reasonably good accuracy using optimally fitted parameters.