Kinetics studies of sustainable biodiesel synthesis from Jatropha curcas oil by exploiting bio-waste derived CaO-based heterogeneous catalyst via microwave heating system as a green chemistry technique

Waste oyster shells (WOS) have been progressively becoming a significant environmental issue, specifically in terms of solid waste management, which is one of the considerable barriers to the actualization of a sustainable planet. Therefore, in this present work, the CaO-based heterogeneous catalyst was developed from the recycled waste oyster shells and subsequently utilized as an efficient and excellent renewable source of the heterogeneous catalyst during the transesterification reaction of Jatropha curcas oil (JCO) for the synthesis of biodiesel. Consequently, the catalyst was prepared by calcination and characterized using different instrumental techniques, including XRD, EDS, FTIR, SEM, and BET. Under optimized conditions, the catalyst exhibited outstanding catalytic performance in converting JCO to sustainable biodiesel with a considerable yield of 91.1% under 180 min reaction time, 800 W microwave power, 65 degrees C reaction temperature, 9:1 methanol to oil ratio (MTOR), and 5 wt% catalyst loading. The reusability study revealed that WOS-derived catalyst was able to attain relatively high biodiesel yield at the first two reaction cycles, and more so, the catalyst could be potentially recycled for at least up to the 5th cycle to produce a relatively high amount of biodiesel. Furthermore, the base-catalyzed transesterification reaction was discovered to have activation energy (Ea) of 9.58 kJ/mol. The physicochemical properties of the JCO biodiesel were studied in accordance with international criterions such as ASTM and EN standards.