Microwave irradiated transesterification of croton megalocarpus oil – process optimization using response surface methodology

Abstract

Biodiesel is a renewable, biodegradable and environmentally friendly fuel which has the highest potential to replace petrodiesel. In Kenya, Croton megalocarpus oil has been shown to be a viable source of non-edible feed to produce biodiesel. Biodiesel is produced by transesterification of oil with an alcohol in the presence of a catalyst. Microwave irradiation is a superior heating mode as compared to conventional heating. Optimization studies for the transesterification of Croton megalocarpus oil employing homogeneous NaOH catalyst were carried out by conventional heating and microwave irradiation. Box Wilson Central Composite Design was used to optimize process variables of methanol-to-oil ratio, catalyst concentration, reaction temperature for the case of conventional heating; and methanol-to-oil ratio, catalyst concentration, reaction time for microwave irradiation. The yield of fatty acid methyl ester (FAME) was correlated as a function of the reaction variables in form of a quadratic equation. The correlation was plotted in response surface and contour plots to indicate the effect of operation variables and to identify areas of optimal yield. Croton oil was characterized by standard methods. Gas chromatography was used to obtain FAME yield. FAME was analyzed for properties as a biodiesel fuel and it satisfied the international standards.