Strategy for Regulation from Heterogeneous Nucleation to Homogeneous Nucleation: Application of Ultrasound

In this study, the nucleation rate and the corresponding nucleation parameters were calculated by measuring the induction time of isonicotinamide (INA) in ethanol, and it was demonstrated that the nucleation of INA is controlled by kinetics. We found that ultrasound can control the nucleation rate of INA in different supersaturated INA–ethanol systems and play a promoting or inhibiting role. The underlying mechanism for those phenomena was supposed to be the jointly effects of ultrasonics, where the cavitation bubbles generated by ultrasonic pretreatment undergo rupture leading to the collision of solute molecules in solution or the dispersion of solute molecules, and the energy generated by ultrasonics can influence the intermolecular hydrogen bond interaction in solution. In addition, the introduction of ultrasonics was found to promote the nucleation mechanism transformation from heterogeneous nucleation to homogeneous nucleation, through the homogeneous dispersion of solute molecules in solution, which we believe to be due to the micromixing mechanism of the ultrasonic. The transition from heterogeneous nucleation to homogeneous nucleation through introduction of ultrasonics provides a feasible approach to avoid heterogeneous nucleation and promote homogeneous nucleation and also provides a new perspective for controlling the crystallization process.