Eco-benign biodiesel production from waste cooking oil using eggshell derived MM-CaO catalyst and condition optimization using RSM approach

Abstract Fatty acid methyl ester (FAME) was produced from waste cooking oil (WCO) utilizing eggshells derived solid base catalyst. Eggshells derived multi modal CaO (MM-CaO) also provides a cost-effective way for the preparation of green fuel. The nano-scaled MM-CaO was prepared using ball milling followed by calcination at 800 °C for 2 h form eggshells powder. The characterization of calcined powder was executed by XRD, EDX, SEM and FTIR techniques. Diffractogram of MM-CaO showed cubic crystal structure and presence of calcium, carbon and oxygen was confirmed by EDX. The morphology of MM-CaO was revealed by SEM having bandgap energy (3.02 eV) which declared MM-CaO as photoactive in solar range. Catalytic transesterification process furnished 75.2% yield, whereas in photocatalytic process, 86.8% yield was obtained at optimum conditions (temperature 50 °C, reaction time 180 min and 1.5 g catalyst dose). The FAME formation was monitored by GC and FTIR analysis. Physiochemical properties of produced biodiesel were also determined and equated with standards. Results depicted that MM-CaO is highly efficient for conversion of WCO to biodiesel.