With the help of ultrasound radiation, over 98% FFA conversion
efficiency of H2SO4catalyzed pre-esterification of J. curcas oil with
a 20 mg KOH/g initial AV was obtained at the optimum conditions
of 18% methanol (wt% of oil) and 1.2% H2SO4catalyst (wt% of oil) in
the ultrasonic field of 900 W/L in 90-min reaction time.
Comparing the apparent forward reaction rate constants k
A
þand
reverse reaction rate constants kobtained under condition of
ultrasonic radiation with those under condition of mechanical
stirring shows that ultrasonic radiation could contribute to the
remarkable increase in k
A
þ
, so high pre-esterification conversion
efficiency was obtained, which suggested ultrasonic radiation to be
useful for effective FFA elimination from the oil.
Since the ultrasonically assisted pre-esterification could take
place at about room temperature (30 8C), much below the boiling
point of methanol at which conventional acid-catalyzed esterification can take place obviously, so it could effectively reduce
external heat energy