Shown in Fig. 4a, the initial boiling point of the biodiesel (IBP)
was 213 C compared to 162 C for diesel. A much narrower boiling
range but higher value could be observed in the case of the biodiesel
than in the case of diesel. The boiling temperatures kept almost
constant at a value of 330 C from 20 vol% fraction to 70 vol% fractio
while it increased steadily in the case of conventional diesel,
which was an average of 10–12 C/10 vol% recovery. This narrow
range can be explained as the biodiesel consists mainly of alkyl esters
that have a little difference in the boiling temperature. The difference
in boiling points among pure fatty acid methyl esters was
approximately 20–30 C. The distillation curve behaviour was similar
for the biodiesel obtained from this study to those obtained
from soybean oil and rapeseed oil, which had a 8–10 C different
boiling range from 10 vol% to 90 vol% [19].