SUMMARY
This work investigates the efficacy of hot batch extraction process on castor seeds using Soxhlet extraction apparatus with normal hexane as solvent. The seeds obtained were pretreated by decoction process whereby, both water and protein content therein were drastically reduced. The effect of the yield on duration of extraction, solvent volume and mass were carried out by adopting a central composite design of response surface methodology and based on the statistical analysis and optimization of various operating variables using a statistical Design Expert software version 6.0.8 (STAT-EASE Inc., Minneapolis, USA) A second order quadratic model was developed in order to correlate the three variables to the response. The optimum conditions for hot batch extraction process of crude castor oil were found to be 150 minutes period of time, 160 ml of solvent volume and 99.9% of mass. At the calculated optimum conditions, the yield was 80.7% at the point desirability of 99.2%. Acid value of 0.45mgKOH/g and calculated 0.23% value of free fatty acid were found to be within the standard range for biodiesel production. The mathematical model developed was found to adequately describe the compatibility with the data predicted and accurate statistical prediction of the optimum yield conditions and the quality of crude castor oil were established.