Investigation on the effect of ultrasonic-assisted transesterification for green synthesis of glycerol carbonate from crude glycerol

The present work demonstrates the utilization of ultrasonic-irradiation for synthesis of glycerol carbonate (GC) with direct use of crude glycerol (C.Gly) and dimethyl carbonate (DMC). This transesterification reaction was catalysed by calcium oxide (CaO) and the effect of ultrasonic-assisted transesterification reaction was studied. In order to verify the contents of C.Gly, the C.Gly obtained from biodiesel production plant was characterized and the results showed that C.Gly consists of 71.21%w/w glycerol, 16.01%w/w of moisture, 7.10%w/w of methanol, 2.76%w/w of ash, 3.60 %w/w of soap and 10.02%w/w of matter organic non-glycerol (MONG). Subsequently, effects of reaction temperature, reaction time, molar ratios of reactants and catalyst loading on C.Gly conversion and GC yield have been investigated. The highest yield of GC (95.41%) was attained with 9 mol% of CaO catalyst loading, 3:1 molar ratio of (DMC:C.Gly) at 70 °C for 90 min. The yield of GC was observed to rise with all the reaction parameters till the optimum conditions obtained. Moreover, the yield of GC obtained from ultrasonic-assisted was compared with the conventional-heating method done in the previous study. It was noticeable that the yield of GC obtained via ultrasonic-assisted was found to be 51.44% better than conventional-heating transesterification. In conclusion, the production of GC via ultrasonic-assisted transesterification shows better feasibility than that of the conventional-heating method.