2. The mathematical model for biodiesel production using
chemical catalyst
To describe a simple mathematical model for the alkali catalytic
transesterification reaction of Jatropha Curcas oil, the following
assumptions have been made.
(A1) Transesterification of vegetable oil with methanol consists of
three stepwise and reversible reactions [13,40].
(A2) Since there is only little water (0.2%, w/w) in the reaction
mixtures and negligible free fatty acid is detected in the system,
the hydrolysis reaction could be negligible [41].
(A3) Mixture of Jatropha Curcas waste food oil that contains 1 wt%
FFAs. TG, BD, FFA might take part in saponification with the
catalyst KOH [42].
(A4) Base catalyzed transesterification reaction for biodiesel production
form Jatropha Curcas oil with methanol (AL) involves
three reversible steps [40]. Here, in the first reversible step,
triglycerides (TG) reacts with alcohol (AL) to produce diglycerides
(DG) which further reacts with AL to produce monoglycerides
(MG) in the second reversible step. Finally, MG
reacts with AL to give glycerol (GL) as by product. At each
reaction step, one molecule of biodiesel (BD) is produced
for each molecule of AL consumed. The kinetic steps are
shown by the following sequential reaction
TG þ AL
k1
k2
DG þ BD;
DG þ AL
k3
k4
MG þ BD;
MG þ AL
k5
k6
GL þ BD:
ð