Ultrasonic free fatty acids esterification in tobacco and canola oil.
D C Boffito, F Galli, C Pirola, C L Bianchi, G S Patience
Author Information
D C Boffito: Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133 Milano, Italy. Electronic address: daria-camilla.boffito@polymtl.ca.
F Galli: Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133 Milano, Italy.
C Pirola: Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133 Milano, Italy.
C L Bianchi: Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133 Milano, Italy.
G S Patience: Polytechnique Montréal, Departement de Génie Chimique, 2900 Édouard-Montpetit, 2500 Chemin Polytechnique, H3T 1J4 Montreal, Canada.
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 (20°C and 40°C vs. 63°C): at 20°C, 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 20°C and 40°C, respectively.
