This study investigated the solubility of chlordiazepoxide in supercritical carbon dioxide (SCCO₂) at pressures ranging from 12 to 30 (MPa) and temperatures ranging from 308 to 338 (K). The measured solubilities ranged from 19.8 to 576 parts per million (ppm), or mole fractions of 0.0198 × 10⁻³ to 0.576 × 10⁻³. We used two equations of state (SRK and ECM-PR), enlarged liquid models, and semi-empirical analysis to assess the experimental data. Applying these models to the experimental solubility data of the chlordiazepoxide-SCCO₂ system revealed that Chrastil’s empirical models best aligned with the two sets of data. An important step in understanding the system’s behavior was applying the SRK and UNIQUAC models to the drug’s solubility data. Density-dependent empirical models, particularly the Chrastil correlation (AARD% = 5.30, R² = 0.996) and the UNIQUAC model (AARD% = 6.12), provided the highest predictive accuracy for chlordiazepoxide solubility in SCCO₂. In contrast, cubic EoS models (SRK and ECM-PR) exhibited significant deviations, with AARD% values approaching 20%, suggesting their limited reliability for this system. The UNIQUAC model indicated excellent accuracy, with AARD% of 6.12 and R2 of 0.981 in correlating solubility data of this binary system.
Ardestani et al. (Wed,) studied this question.