Experimental Measurement and Thermodynamic Modeling of Capecitabine (an Anticancer Drug) Solubility in Supercritical Carbon Dioxide in a Ternary System: Effect of Different Cosolvents

Solubility of capecitabine (CPT) in a ternary system (supercritical carbon dioxide (sc-CO2) + CPT + [methanol, ethanol, and dimethyl sulfoxide (DMSO)] as cosolvents) was measured at different temperatures (308.15-348.15 K) and pressures (100-350 bar). CPT solubility in the presence of methanol, ethanol, and DMSO was in the range of 3.18 x 10-5 to 120.29 x 10-5, 0.64 x 10-5 to 71.9 x 10-5, and 0.85 x 10-5 to 94.8 x 10-5 mole fraction, respectively. A significant solubility improvement of CPT in sc-CO2 is shown by comparison with its solubility in a binary system (sc-CO2 + CPT) reported in the literature (Yamini et al. 2012). The solubility data were correlated by several well-known empirical models of ternary systems. Among them, the Jouyban et al. model produced the best correlation with average absolute relative deviation (AARD %) of 10.58, 9.21, and 8.92% for methanol, ethanol, and DMSO, respectively. Also, the solubility data of the methanol cosolvent were correlated by Peng-Robinson (PR-vdW2), Soave-Redlich-Kowng (SRK-vdW2), and perturbed-chain polar statistical associating fluid theory (PCP-SAFT) thermodynamic equation of state-based models. According to the mean AARD % value of PR equation of state (EoS) (20.32%) and corresponding R-adj (0.9866), it could be concluded that PR EoS shows a better performance in comparison with other thermodynamic models.