Chiang Mai Journal of Science

The Response Surface Methodology (RSM) based on Central Composite Rotatable Design (CCRD), was used to evaluate four trans-esterification reaction parameters i.e. reaction temperature, catalyst concentration, reaction time and methanol-to-oil molar ratio in order to obtain high and better yield. A 24 full factorial CCRD was applied, using four different variables at five levels; each parameter leads to 30 experiments to yield Eruca sativa oil-methyl esters (EOMEs). The molar ratio of methanol to oil and catalyst concentration were the most significant (P < 0.5) factors affecting the yield of EOMEs. A linear relationship was recorded between observed and predicted values (R2 = 0.97). Using multiple regression analysis, a quadratic polynomial equation was recognized for methyl ester yield (MEY). The quadratic terms of molar ratio and catalyst concentration showed a significant impact on yield. The interaction terms of molar ratio and catalyst concentration with reaction time revealed positive influence on MEY (P < 0.05). The optimal reaction conditions for transesterification of oils were catalyst concentration of 0.8%, reaction temperature 65 °C, CH3OH to oil ratio of 6:1 and reaction time 120 min leading to production of 95.88% Eruca oil MEY. The RSM was found to be a suitable technique for optimizing transesterification process, and manufactured fuel properties were within the ranges of EN 14214 and ASTM D6751 standards.