EFFECT OF TEMPERATURE AND PERCENTAGE OF
INITIAL CATALYST ON THE IN-SITU PRODUCTION
OF BIO-DIESEL FROM CASTOR OIL BEAN SEED
USING RESPONSE SURFACE METHODOLOGY
The use of vegetable oil and animal fats for biodiesel production has recently become a great concern
because of the competition with food materials. As the demand for vegetable oil increase tremendously
in recent years it has become impossible to justify the use of these oils for fuel production. Insitu
trans-esterification process uses the oil (triglycerides) in the oil seed directly without the need for
initial extraction as compared with the conventional trans-esterification. Castor oil bean seed contains
between 35 and 55% oil and does not compete with food grade oil because of the seed’s toxicity. This
study evaluated the effect of temperature and percentage of initial catalyst on yield of castor ethyl
ester. Raw castor oil bean seed kernel at moisture content of 4.68 % (db) was subjected to in-situ
trans-esterification in a batch processor with ethanol as the solvent and sodium hydroxide as the catalyst.
Central composite design (CCD) of the Response surface methodology was applied to evaluate
the main and interactive effects of initial catalyst amount (0.5 – 1.5%) and reaction temperature (40 –
70OC), on yield of castor ethyl-ester, at reaction time of 120 minutes and alcohol-seed weight ratio of
1:1. A quadratic non-linear polynomial model was obtained to describe the effect of the factors on
yield. The model was significant (P< 0.05) with a non- significant Lack-of-Fit value (P< 0.05) and R2
value of 0.944. Second order response surfaces and contour plots obtained from the model revealed
that initial catalyst amount was the more effective factors on yield while reaction temperature had less
effect. The Temperature–percentage of initial catalyst interaction was small and negative, due to the
combined effects of formation of by-products (soaps) and saponification. The biodiesel produced from
ground castor oil bean seed during this study met the requirements of ASTM standard D6751-02 but
specific gravity was higher than the ASTM standard confirming that biodiesel produced from castor
bean seed using the in-situ technique can be used as replacement fuel for fossil diesel