Determination of the Florfenicol drug solubility in supercritical CO2 and thermodynamic modeling by PR EoS/vdW and density-based correlations

In this study, the solubility of Florfenicol in supercritical carbon dioxide (SC-CO₂) was investigated for the first time under various conditions: pressures (P) from 120 to 270 bar (120 < P ≤ 270) and temperatures of 308, 318, 328, and 338 K. The equilibrium solubility parameter ranged from 0.22 to 3.65 kg/m3, resulting in mole fractions (y) ranging from 0.45 × 10− 4 to 5.74 × 10− 4. Two different modeling approaches were applied to correlate the drug solubility data. The first approach used an equation of state, specifically the Peng-Robinson equation of state with the van der Waals Type I mixing rule, yielding an average absolute relative deviation (AARD) of %10.48. The second approach comprised 22 density-based correlations categorized into three groups based on their independent variables: (T, ρ), (P, T), and (P, ρ, T). These correlations included those by Bartle et al., Garlapati and Madras (I & II), Chrastil, Andonova and Garlapati, Kumar and Johnston, del Valle and Aguilera, Sung-Shim, Ch and Madras, Adachi and Lu, Alwi-Garlapati, Bian et al., Cherif Si-Moussa, Mendez-Santiago and Teja, Jafari Nejad et al., Sodeifian et al. (Models I & II), Keshmiri et al., Jouyban et al., Khansary et al., Hozhabr et al., and Gordillo et al. These models have between three and six adjustable coefficients. Among the (T, ρ) category, the Adachi and Lu model showed better agreement (AARD = 4.91%), while among the (P, ρ, T) category, the Mendez-Santiago and Teja model showed the best agreement (AARD = 4.19%) with the solubility data of Florfenicol. Finally, the enthalpies of vaporization, total, and solvation were determined for the Florfenicol/SC-CO₂ system.