Abstract
The influence of ultrasonication and agitation on the induction of nucleation in the reaction crystallization of cerium carbonate was investigated in a semi-batch crystallizer. When the cerium chloride and sodium carbonate reactants were constantly injected, the induction time depended significantly on ultrasonication and agitation. Due to the acoustic cavitation of ultrasonication promoting micromixing of the reactants, the induction time of cerium carbonate was markedly reduced. Simultaneously, the acoustic cavitation appeared to reduce the energy barrier of nucleation, inducing nucleation at a lower supersaturation level than with the turbulent fluid motion of agitation. However, the acoustic stream of ultrasonication did not promote the induction of nucleation. Meanwhile, agitation also facilitated the induction of nucleation due to turbulent mixing of the reactants. The micromixing resulting from agitation meant the supersaturation in the solution increased rapidly when increasing the agitation speed, thereby reducing the induction time. The influence of ultrasonication and agitation on the induction of nucleation was also compared in terms of the energy dissipation. With the same energy dissipation, ultrasonication was much more effective than agitation for induction, possibly due to its unique feature of acoustic cavitation.
