Optimization of biodiesel production from castor oil by response surface methodology

This work investigated the possibility of using response surface methodology based on a four factor five level central composite design to optimize biodiesel production from castor oil. The reaction variables were oil: ethanol ratio, lipozyme concentration, time and temperature. The properties of the biodiesel produced were assessed. The linear coefficient of lipozyme concentration (B), temperature (D), the quadratic coefficient of lipozyme concentration (B2), time (C2), temperature (D2), the interaction of oil/ethanol ratio and lipozyme concentration (A*B), the interaction of lipozyme concentration and time (B*C) had significant effect on the biodiesel yield (p<0.05).The other variableswere not significant (p>0.05).The specific gravity was (0.91), refractive index (1.41 + 0.01), viscosity (14.1), cetane number (53.9), calorific value (38.0+ 0.10), flash point (150oC), cloud point (7oC) iodine value (101 + 0.53), acid value (0.57 + 0.01), and saponification value (180+0.25). Maximum yield was found to be 93.0% under the conditions of oil: ethanol ratio of (1:7.14), lipozyme concentration (40 U), time (165 min) and temperature 50oC.The properties of the biodiesel produced were largely in conformity with ASTM D6751 standards.Keywords: Biodiesel, castor oil, optimization, transesterification