Development of the CPA Equation of State for Phase Equilibria and Solubility Calculations in Gas Anti-Solvent Systems

Supercritical fluids are recently used as a new method for producing nanoparticles. The purpose of this study is to thermodynamically model and solubility calculations of the gas anti-solvent process. For this purpose, a thermodynamic model based on the cubic-plus-association (CPA) equation of state (EoS) was applied to determine and predict the solubility of solid solutes in the process and to optimize the operational conditions. At the first, the optimum parameters of the CPA EoS were obtained for the pure compounds, using simultaneous regression of liquid density and vapor pressure data. Then, the binary interaction parameters were optimized using phase equilibrium experimental data. By applying these parameters, the modeling of the phase behavior of six solid-liquid-vapor (S-L-V) systems containing CO‌2 + toluene + naphthalene, CO‌2 + 1-propanol + salicylic acid, CO‌2 + ethyl acetate + salicylic acid, CO2 + ethanol + acetaminophen, CO‌2 + acetone + acetaminophen and CO2 + acetone + cholesterol was performed at the specific temperature and pressure ranges. The modeling results of this work were also compared with the literature data and the calculated results of the SRK EoS.