CALCULATIONS OF SOLUBILITIES OF AROMATIC-COMPOUNDS IN SUPERCRITICAL CARBON-DIOXIDE

Solubilities of five aromatic compounds in supercritical carbon dioxide are calculated in this work by using the Patel-Teja equation of state. Unlike the traditional van der Waals mixing rules, the energy parameter of the equation of state is evaluated by equating the excess free energy calculated by the equation of state to that from a UNIFAC group contribution liquid model. New UNIFAC group interaction parameters of carbon dioxide and various hydrocarbon groups are obtained through regression of experimental vapor-liquid equilibrium data. A new mixing rule for the excluded volume parameter of the equation of state is proposed, and a generalized correlation of that parameter is presented. With the new mixing rules, solubilities of aromatic solids in supercritical carbon dioxide can be calculated satisfactorily. The results are comparable to those computed by using the van der Waals mixing rule with multiple best-fitted unlike pair parameters.