The enhancement of the crystallization process through high pressures was studied by using ribavirin (RVB) as a model compound. The effects of high pressure on crystallization thermodynamics, nucleation kinetics, and process yield were evaluated and discussed. The solubility of ribavirin in three pure solvents was measured at different pressures from 283.15 to 323.15 K. The results indicate that the solubility data of ribavirin decreased slightly when pressure was increased. The induction time of the cooling crystallization of ribavirin under different pressures was measured. The results show that high pressure could significantly reduce the nucleation induction period. Furthermore, the nucleation kinetic parameters under different pressures were calculated according to the classical nucleation theory. The effect of high pressure on the anti-solvent crystallization of ribavirin was also studied.

To obtain crystal products with ideal morphology and better quality, it is important to fully understand and grasp the affecting mechanism of solvents on crystal morphology. In this work, the interactions between solvent/solute molecules and different crystal faces of pyriproxyfen are investigated by a combination of experiments and molecular simulations. It is found that pyriproxyfen crystals grow into a lamellar morphology in methanol and ethanol, while the crystal grows into a three-dimensional shuttle morphology in n-butanol and n-heptane. Molecular simulations reveal that the molecular arrangement of crystal faces makes the alcohol hydroxyl adsorption sites exposed in different degrees, and the (002) face is more sensitive to alcohol hydroxyl than other faces. The adsorption of alcohol hydroxyl groups hinders the growth of crystal planes, so (002) and (102) faces become the main crystal planes in methanol and ethanol, and the lamellar crystal is formed. The developed knowledge of the growth mechanism based on the interaction between the solvent and crystal interface can be conducive to the further optimization of the pyriproxyfen crystal products.