Performance Evaluation of Waste Chicken Eggshell and Waste Seashell as a Heterogeneous Catalyst for Biodiesel Production

Due to their reusability, heterogeneous catalysts for biodiesel production have gained popularity. If the commercial-grade heterogeneous catalyst could be replaced with CaO generated from eggshells (which is a waste product) and seashells (which is abundantly available in Sri Lanka) would be beneficial for the sustainability of the process and circular economy. This work em-phasizes and summarizes the derivation of CaO from eggshell and seashell, the investigation of the produced catalyst using a scanning electron microscope, and the comparison of the two by powder X-ray diffraction. CaO produced from eggshell, and seashell exhibited slight differences in its surface structure. However, there are larger voids in the seashell-derived catalyst due to the release of CO2 during calcination. The derived catalyst and commercial CaO were both employed to produce biodiesel under identical operating circumstances, including a 12: 1 Methanol-to-oil molar ratio, 60 °C operating temperature, 120min reaction time, 600 rpm, and a 5 wt.% catalyst concentration. The biodiesel yield was computed and compared for all three scenarios involving catalyst recycling. Commercial grade CaO produced the highest yield, followed by seashell- and eggshell-derived CaO. Both derived catalysts are less pure than commercial CaO, as they were produced with CaCO3 in addition to CaO