A dual frequency US reactor integrated with a horizontal
mechanical stirrer has been designed to produce biodiesel from
palm oil and methanol in the presence of NaOH as a catalyst.
Two transducer frequencies, 20 and 50 kHz, were employed in four
possible locations along the length of the reactor. The results
showed that this reactor provided high methyl ester yield in only
5 min reaction time, whereas the MS reactor required 60 min.
The optimal operating conditions were; a methanol to oil molar
ratio of 6 and a NaOH catalyst loading value of 1% wt of oil as
operated in the circulation of reaction mixture with feed flow rate
55 mL/min. The influence of transducer number on methyl ester
yield was more important than differences in transducer frequency
and location along the length of the reactor. The identical distance
of each transducer along the length of the reactor was able to
provide uniform cavitational intensity and resulted in the same
effect at the different locations. Moreover, the properties of
biodiesel produced from this reactor conform to the ASTM
standard. The combined MS–US reactor enhanced the biodiesel
production with better performance than the MS and US reactors
alone