Waste cooking oil and waste chicken eggshells derived solid base catalyst for the biodiesel production: Optimization...

Waste chicken eggshells were used to derive two catalysts labeled in this study as Eggshell-CaO_C-H-D and Eggshell-CaDG. Both these catalysts were characterized by FTIR, XRD, BET, SEM, and basic strength was determined by the Hammett indicator method. The transesterification of waste cooking oil was carried out to compare the catalytic activity of Eggshell-CaDG and Eggshell-CaO_C-H-D. The effect of various reaction parameters-methanol molar ratio, temperature, speed of agitation, and catalyst loading on the progress of the reaction was also tested to produce higher biodiesel yield. Eggshell-CaDG catalyzed reaction produced 96.07% biodiesel under the optimized reaction conditions of methanol molar ratio 10:1, catalyst loading 1.50 wt%, temperature 60 °C and speed of agitation 300 rpm with a reaction time of 50 min. Whereas, Eggshell-CaO_C-H-D was yielded 93.10% biodiesel for the optimized operating parameters-methanol molar ratio 12:1, 400 rpm, 65 °C, catalyst loading of 3 wt% in the reaction time of 90 min. The reusability for both the catalysts was tested up to five cycles and found that biodiesel yield was decreased with successive cycles. The activation energies of the Eggshell-CaDG and Eggshell-CaO_C-H-D were found to be 31.39 and 54.05 kJ mol^-1, respectively. The physicochemical properties of the biodiesel were also found as per the ASTM standard range.