A cleaner process for green biodiesel synthesis from waste cooking oil using recycled waste oyster shells as a sustainable base heterogeneous catalyst under the microwave heating system

Abstract In this study, biodiesel synthesis from waste cooking oil (WCO) using waste oyster shells derived catalyst (CaO-based catalyst) as a sustainable based heterogeneous catalyst under a microwave heating system technology was investigated. The CaO-based catalysts were characterized by Fourier Transform-Infrared (FTIR), X-ray diffraction (XRD), Electronic Data System (EDS) and Brunauer-Emmett-Teller (BET) measurements. Under optimized conditions, this study has produced tentative results with considerable performances in relations to biodiesel synthesis as follows: (1) the intensification in relation to reaction time from 120 to 180 min has significantly increases the biodiesel yield, which declines with a more intensification to 120 min; (2) the synthesis of biodiesel in this study has proved to increase with an upsurge reaction of power; (3) whereas 180 min reaction time with 800 W microwave power, a methanol-to-oil molar ration of 9:1, a reaction temperature of 65 °C; and 6 wt% catalyst concentration was revealed to be optimal and perfect reaction conditions for this present research work. The highest biodiesel yield was recorded at 87.3% in this study. Whereas the activation energy (Ea) for the catalyzed transesterification reaction was found to be 9.56 kJ/mol. In a nutshell, waste oyster shells were recycled as a sustainable base heterogeneous catalyst to synthesize new biodiesel from WCO, which can be used in diesel engines to address air pollution, especially pollutant emissions from diesel automobiles.