Continuous microwave-assisted biodiesel production

MSc (Engineering Sciences in Chemical Engineering), North-West University, Potchefstroom Campus, 2016The impetus of this study focuses on the production of fuel-substitute i.e. biofuels. This arises from its similar properties with petroleum diesel and being environmentally benign. In particular, biodiesel is defined as composed of mono-alkyl esters with long fatty acids chains. The primary aim of the study was to investigate the effect of surface area of the reactor vessel when producing biodiesel using continuous microwave-assisted transesterification. The effects of energy input on FAME yields and biodiesel properties were determined. Three different tubular reactor coils with same volume (100 ml) and different surface area (0.082, 0.057, and 0.045 m2) were used in this study. The experiments were carried out in one of these reactors, with a constant 6:1 methanol-to-oil molar ratio, and constant 1wt% KOH catalyst, varying residence time (40, 50, and 60 s) and 400, 500, 600 W microwave powers. According to results, the highest FAME yield was obtained at 50 s residence time, 400 W microwave power with an energy input of 67.96 J/g at reactor surface (0.082 m2). A further increase of power usage led to a decrease in FAME yields. Produced biodiesel was analysed using gas chromatography (GC), Fourier transformer infrared spectrometer (FTIR) eraspec, Eraflash, and Viscometer. Biodiesel was tested according to SANS 1935 standard specification. The properties of produced biodiesel met the SANS 1935 standard specification. Viscosity and oxidation stability did not meet the requirements. It was noticed that when oxidation stability values are low, the viscosity decreases. An antioxidant plays a pivotal role to stabilise biodieselMaster