Phase Equilibrium Study for the Separation of Solid Components Using Supercritical Carbon Dioxide

The equilibrium mole fraction solubility of low volatile solid components (naphthalene and phenanthrene) in supercritical pure carbon dioxide was studied at temperature range (308.15-333.15 K) and pressures up to 200 bars. In the present study a measure of the effect of temperature and pressure were considered in the extraction process using supercritical carbon dioxide. The experiments were carried out using a designed apparatus similar to that used by King et al., [1]. In this apparatus, the extracted gas (carbon dioxide) was re-circulated continuously over the component to be extracted via a sample bomb till equilibrium is reached. The sample bomb is then isolated and its contents were analyzed. The results of analysis showed that the solubility of naphthalene and phenanthrene expressed in mole fraction depend strongly upon the pressure (density) of the supercritical carbon above the critical density. The obtained laboratory data are correlated with three cubic equations of state, Redlich-Kwong (RK), Soave-Redlich- Kwong (SRK), and Peng-Robinson (PR). Comparison of experimental phase equilibrium data with the results predicted by the equations of state shows good representation.