Supercritical CO2 utilization for solubility measurement of Tramadol hydrochloride drug: Assessment of cubic and non-cubic EoSs

Abstract

In this study, the solubility of the tramadol hydrochloride (T-HCl) drug in supercritical carbon dioxide (SC-CO2) was determined for the first time. The experiments were conducted at various operating pressures (100–270 bar) and temperatures (308–338 K). The solubility of T-HCl ranged from 0.309 × 10−4 to 1.384 × 10−4 in terms of mole fraction. Two different models, namely the Soave-Redlich-Kwong (SRK) and the simplified perturbed chain statistical associating fluid theory (sPC-SAFT) EoSs, along with seven semi-empirical correlations (including the Kumar-Johnston, Sung-Shim, Garlapati and Madras, Chrastil, Bian et al., Bartle et al., and Sodeifian et al., models), were employed to predict the solubility of T-HCl in SC-CO2. The findings indicated that the sPC-SAFT EoS (with an average absolute relative deviation of 10.18%) and the Sung-Shim correlation (with an average absolute relative deviation of 7.29%) outperformed the other models, respectively. The total, solvation, and vaporization enthalpies of the T-HCl/SC-CO2 binary system were estimated by applying these semi-empirical correlations.