Synthesis and Characterisation of Soya Bean Oil Based Biodiesel under Optimal Sonic Frequency

Abstract

The present study reports the transesterification of soya bean oil with methanol using sodium hydroxide (NaOH) as catalyst under the influence of simultaneous sonic and mechanical energies. The purpose was to optimise the optimal sonic frequency of ultrasonic reactor and optimal reaction conditions, including the amount of catalyst, the oil/methanol molar ratio was also investigated to achieve highest possible yield of soya bean oil methyl ester (SOME) to act as biodiesel. Experimental results showed that simultaneous sonication and mechanical mixing of soya bean oil with methanol might be a potential alternative route compared with the conventional base catalysed method. High reaction yields of ~96% were obtained at 60% sonic frequency, mild irradiation power of 350 W, oil to methanol molar ratio of 1:6, mechanical agitation speed of 200–300 rpm and temperature of 45°C in relatively short reaction time 60 min using 0.2 wt % NaOH. Further, the synthesised SOME was characterised for density, kinematic viscosity, acid number, cetane number, calorific value, flash point, distillation temperature, sulphated ash content, carbon residue and fatty acid composition according to the American standard testing method of analysis (ASTM) to ensure the quality of SOME to act as biodiesel.