Ultrasound accelerates the free fatty acids esterification rate by reducing the mass transfer resistance
between methanol in the liquid phase and absorbed organic species on Amberlyst
46 catalyst. The
reaction rates of canola oil is three times greater than for tobacco seed oil but half the reaction rate of
pure oleic acid as measured in a batch reactor. The beneficial effects of ultrasound vs. the conventional
approach are more pronounced at lower temperatures (20C and 40C vs. 63C): at 20C, the free fatty
acids conversion reaches 68% vs. 23% with conventional mechanical stirring. The increased conversion is
attributed to acoustic cavitation that increases mass transfer in the vicinity of the active sites. The
Eley–Rideal kinetic model in which the concentration of the reacting species is expressed taking into
account the mass transfer between the phases is in excellent agreement with the experimental data.
Ultrasound increases the mass transfer coefficient in the tobacco oil 6 and 4.1 fold at 20C and 40C,
respectively