a cavitation bubble collapses near a solid surface, liquid jets are
produced and high-speed jets of liquid are driven into the surface
of a particle (due to the asymmetric collapse of bubbles), resulting
in enhanced transport of the species towards the solid surface[27].
For this reason US has been adopted extensively to promote
various reactions, among which heterogeneously-catalysed processes[28].
In the presence of two immiscible liquids, US forms fine emulsions, thereby increasing the surface area available for the reaction
between the two phases. The cavitation may also lead to a localized
increase in temperature at the phase boundary. As a consequence,
both mass transfer rates and global reaction rate increase[29].
Emulsions produced by sonication are also reported to be more
stable than those formed conventionally[30].
In this manuscript, we present the results of the ultrasonic FFA
esterification of raw tobacco seed oil, refined canola oil and pure
oleic acid in the presence of acid ion exchange resins and compare
the FFA conversion with the conventional method. This study
includes a kinetic model that takes into account the mass transfer
at the phase boundaries in the reaction system methanol-oil
(+FFA)-catalyst. Mass transfer has been largely ignored in the scientific literature