(477g) Nucleation Behavior of Ethyl Vanillin: The Partial Dependence of Kinetic Parameters on Interfacial Energy

Yang, J., Tianjin University
Gong, J., Tianjin University
Xu, S., Tianjin University
Wang, J., National Engineering Research Center for Industrial Crystallization Technology, School of Chemical Engineering and Technology, Tianjin University
The experimental metastable zone width (MSZWs) of ethyl vanillin (EVA) in ethanol, n-propanol and n-butanol were measured by the polythermal method to describe the nucleation behavior in its unseeded cooling crystallization. In accordance with the classical nucleation theory (CNT), the dependences of MSZWs on saturation temperature T0 and cooling rate R were mainly discussed via Nývlt's semiempirical model and modified Sangwal's theory, respectively. Meanwhile, the pre-exponential factor A, crystal-liquid interfacial energy γ and the corresponding critical parameters rcrit (critical nucleus size), △Gcrit (critical Gibbs free energy) can be obtained. It is interesting to find that γ increases linearly with decreasing T0 and increasing R, while the value changes of A do not have regularity against thermodynamics and kinetics. As the result, the increase or decrease of nucleation rate J mainly depends on the increments of γ more than the slight variation of A. Furthermore, it suggests that the thermodynamic dependence of γ is greater for the system with higher supersaturated concentration of solute.