Key words: thermodynamic modelling, Peng-Robinson and CPA (Cubic Plus Association) equation of state, acetylsalicylic acid, salbutamol sulfate, ethanol, dimethylsulfoxide
Thermodynamic modeling of pharmaceutical drugs solubility in supercritical fluids is necessary of optimization of extraction, purification, micronization and other processes. The CO2-ethanol-aspirin and CO2—dimethylsulfoxide (DMSO)—salbutamol sulfate ternary systems were used to show possibility of application of simplified models based on Peng—Robinson cubic equation of state. They were used for descri ption of phase equilibria in the CO2—ethanol binary subsystem at p=0.1—12 MPa and T = 290—345 K and in the CO2—DMSO binary subsystem at p = 0.5—18 MPa and T = 275—350 K. In the case of ternary systems, the data on the pharmaceuticals solubility in the mixed solvents were successfully approximated. Existing data at p = 7.5—35 MPa, T = 298—328 K, x(C2H5OH) = 0 and 3 mol. % were used for aspirin. Salbutamol sulfate solubility in the CO2—DMSO mixture was measures in this work at p = 8.6—21.7 MPa and T = 313—323 K by means of visual method in the thermostatic cell of constant volume. Although the obtained models describe phase equilibria, they disagree with fluid density data, especially for composition that are rich with polar components. Nevertheless, it doesn’t cause problems with usage of cubic equations of state for description of pharmaceuticals solubility in the fluid-based systems.
doi:10.34984/SCFTP.2023.18.2.004