Shockwaves are produced
when the cavitation bubbles collapse and the reagents are mixed
on a micron scale, increasing the surface contact area between
the methanolic methoxide solution and the oil phase. The maximized mass transfer and alcohol vapour generated in the hot spots
strongly accelerate the transesterification reaction. The mixture is
maintained at the same temperature for 15 min under moderate
stirring in the discharge tank (3). Glycerol is then finally allowed
to separate from the crude biodiesel and unreacted oil, via the
action of gravity, in the same tank in 30 min. After glycerol separation, crude biodiesel and the mixture of mono- and diglycerides are
transferred to the premixing tank (1) and stirred for 30 s with the
remaining 25% by volume of methoxide solution, at the reaction
temp. of 55C. The mixture is again sucked by the HC reactor, at
the same flow rate of 390 L/h, and discharged into the second tank
(3), where it is maintained at the same temperature for an additional 15 min under moderate stirring. After 30 min, two clean layers of glycerol and biodiesel are separated in the tank and collected
from the bottom