The production of fuel-quality biodiesel from low-cost,
high FFA feed stocks is investigated in the present study. It
is found that the feedstocks with high FFAs could not be
transesterified with the commercially available alkaline
catalyst transesterification process. The reason is alkaline
catalysts react with the FFAs to form soap that prevents the
separation of the glycerin and ester. A two-step transesterification
process is developed to convert the high FFA oils to
its esters. The first step (acid catalyzed transesterification)
reduces the FFA content of the oil to less than 2%.
The alkaline catalyst transesterification process converts the
products of the first step to its mono-esters and glycerol.
The effects of alcohol to oil molar ratio, catalyst amount,
reaction temperature and reaction duration are analyzed in
each step. Excess addition of sulphuric acid darkens the
product. It has been also found that the conversion efficiency
is strongly affected by molar ratio of alcohol to oil. The
molar ratio of 6:1 favors the completion of alkaline
catalyzed esterification process with in half an hour. The
maximum ester conversion is achieved at the reaction
temperature of 45G5 8C. The viscosity of biodiesel is
nearer to that diesel. The flash point of biodiesel (about
130 8C) is greater than that of diesel and the calorific value
is slightly lower than that of diesel. This two-step
esterification method reduces the overall production cost
of the biodiesel, as it uses low cost unrefined non-edible oils.
The present analysis reveals that biodiesel from unrefined
rubber seed oil is quite suitable as an alternative to diesel.
However, further research and development on additional
fuel property measures, long-term run and wear analysis of
biodiesel-fueled engine is also necessary.