Effect of Solvents on the Optimal Thermodynamic Conditions of Ternary System (CO2, Alcohol, Ampicillin) in GAS Process

The gas antisolvent (GAS) process has been employed for the pharmaceutical micronization. Ampicillin was dissolved in an organic solvent and carbon dioxide as an antisolvent was injected into the solution, consequently, some volume expansion and sharp reduction in liquid solvent power were shown. The particles in GAS process are not seen in any operating conditions. The thermodynamic modeling of GAS can evaluate the operating conditions. In this project, the effect of solvents on the optimal thermodynamic conditions of the binary system (CO2, solvent) and ternary system (CO2, solvent, ampicillin) were investigated. The relative change in the molar volume in different solvents (ethanol, 1-propanol, 1-butanol, and 1-pentanol) was studied for the determination of the optimum operating conditions. The combination of the Peng-Robinson EOS and Vidal and Michelsen mixing rule (LCVM) was selected to determine the optimum operating condition of the GAS process. The effect of solvents on the minimum pressure was investigated. The calculated Pmin was 70, 70.86, 72.2 and 73.4 bar for ethanol, 1-propanol, 1-butanol, and 1-pantanol at, 308.15 K respectively. According to modeling results, when the molecular weight of the solvent was increased, the value of Pmin was increased.