Density measurements of homogeneous-phase fluid mixtures comprising CO2/limonene and CO2/linalool binary systems and correlation with the PC-SAFT equation of state

• Measured densities of CO 2 /limonene and CO 2 /linalool mixtures at high pressure • Used a high-pressure vibration-type density meter with a variable-volume cell • Correlated densities using the perturbed chain-statistical associating fluid theory • Evaluated multiple pure-component parameters for limonene and linalool • Assessed the impact of mixture parameters on the density correlation accuracy Chemical process design relies on accurate knowledge of physical properties; however, it is unknown for a process to have both a single dominant property and broad range of well-documented properties. Supercritical extraction is one such case: while solubility data for essential-oil components in CO 2 are available, information on other physical properties remains limited. This study investigates the previously unreported density of homogeneous-phase fluid mixtures as an additional key property, using limonene and linalool as representative essential-oil components. Densities of the CO 2 /limonene and CO 2 /linalool binary systems are measured with a high-pressure oscillating density apparatus equipped with a circulating pump and variable-volume observation cell. The obtained data is correlated using the perturbed chain-statistical associating fluid theory equation of state, which requires pure-component parameters for each component. Pure-component parameters are often reported in sets obtained through different methods, and limonene and linalool likewise have multiple sets reported. In conventional physical property estimation, a single set is often selected ad hoc with little acknowledgment of the existence of alternative sets. This study examines the impact of pure-component parameter selection on density estimation by performing density correlation on mixtures using each available set of pure-component parameters. The accuracy of the mixture density correlation depends on the precision of the pure-component density estimation, although mixture-related parameters can partially compensate for such deviations. These findings demonstrate the importance of accurate pure-component parameters and complementary role of mixture parameters in improving the reliability of thermodynamic modeling for supercritical CO 2 systems.