Kinetic Modeling of Supercritical Antisolvent Crystallization

In the current study, using experimental data from literature, an empirical correlation of phenanthrene solubility in the mixture of supercritical CO2 and toluene and also another equation to correlate its supersaturation rate with pressure (antisolvent addition rate were determined. Afterwards, the kinetic modeling of supercritical antisolvent crystallization process using the Population Balance Equation (PBE) method was fulfilled. Lax-Wendroff and Crank- Nicholson as a combinatorial numerical algorithm was used to solve the PBE. The simulation was performed at 40C and pressure range between 0.34 and 5.63 MPa by changing the main operating parameter, the antisolvent addition rate (system pressure). To determine nucleation rate, crystal growth rate, crystal size distribution, and mean size, discretization method was used and a numerical solution to the PBE was performed. The results showed that drastic decrease of solubility (mole fraction) from 0.27 to 0.16 was the result of pressure increase from 0.1 to 0.34MPa which followed by high supersaturation generation from 1 to 1.6. By adding the antisolvent, the highest supersaturation was at 6 Mpa. The primary nucleation was superior at 0.3 MPa while the second nucleation increased by the antisolvent addition and the solute precipitation and reached the maximum at 6 Mpa. The particle size distribution showed to have one pick located within small sized particles (class sizes lower than 20) upto 1.79 MPa. By the pressure increase a second pick gradually was appearing and the diagram was changing to binomial.