The effect of high intensity ultrasound (HIU) on the kinetics of crystallization of sucrose: Elimination of latent period

摘要

The application of a technique to eliminate the latent period during crystallization of sucrose by high intensity ultrasound (HIU) was investigated in this paper. Employing HIU (20 kHz, 750 W) to crystallization of sucrose, latent period was eliminated and it was found to obey first order kinetics (K similar to 10(-5)s(-1)) in the temperature range of 30-50 degrees C. Employing Arrhenius equation, the average energy of activation (E-a) estimated as 5.0 kcal mol(-1). Traditional knowledge indicates that crystallization is sufficiently spontaneous; however, the magnitude of "K" and other thermodynamic quantities of the process indicate that crystallization is actually a slow process. Generally, chemical reactions which posses low rate constants, need the high energy of activation. On the contrary, the energy of activation is appreciably less. The energy of activation with a rate constant of the order of 10(-5)s(-1) could be predicted of the order of 20 kcal mol(-1) at 27 degrees C. The low energy of activation for crystallization of sucrose is of interest. A very interesting elucidation can be had from neutron diffraction data and transport property of the sucrose which is discussed in details in this paper.