Abstract
The influence of ultrasonication and agitation on the induction of nucleation in the reaction crystallization of cerium carbonate has been investigated in a semi-batch crystallizer. When the cerium chloride and sodium carbonate reactants are constantly injected, the induction time depends significantly on ultrasonication and agitation. Due to the acoustic cavitation of ultrasonication promoting micromixing of the reactants, the induction time of cerium carbonate is markedly reduced. Simultaneously, the acoustic cavitation appears 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 does not promote the induction of nucleation. Meanwhile, agitation also facilitates the induction of nucleation due to turbulent mixing of the reactants. The micromixing resulting from agitation meant the supersaturation in the solution increases rapidly when increasing the agitation speed, thereby reducing the induction time. The influence of ultrasonication and agitation on the induction of nucleation has also been compared in terms of the energy dissipation. With the same energy dissipation, ultrasonication is much more effective than agitation for induction, possibly due to its unique feature of acoustic cavitation.
