Solar irradiation assisted synthesis of biodiesel from waste cooking oil using calcium oxide derived from chicken eggshell

摘要

The conventional approaches in transesterification have several techno-economic and sustainability challenges. To this end, the utilization of waste resources and renewably sourced energy has tremendous appeal. The present study reports the findings on the transesterification of waste cooking oil (WCO) catalyzed by CaO (sourced from waste chicken eggshells) using solar irradiation based thermal energy. A co-solvent (ethyl acetate) was used to enhance the miscibility of transesterification reactants. The process variables (alcohol to oil molar ratio, catalyst concentration, reaction time, and reaction temperature) were optimized using response surface methodology based Box-Behnken design. During the experiments, the intensity of solar radiation varied, and the reactor temperature ranged between 40 and 46 degrees C. At the predicted optima, a conversion of 90.14% was attained, which was in reasonable agreement with the predicted response (93.64%). A gradual loss of catalytic activity was observed over consecutive batch transesterification runs, and at the end of a 3rd run, 73.13% conversion of WCO was attained. The solar radiation available at the ground level during the experimental period was approximate to 5.15 kW m(-2) d(-1), while the conventional approach (hot-plate based heating) led to an energy input of 2.5 kWh per run at the optimized reaction condition. With process intensification strategies, solar irradiation is poised to become an increasingly sustainable alternative to the conventional approach. The findings of the study present an economical and environmentally benign approach to biodiesel production.