Cu-Doped chicken eggshells: An eco-friendly catalyst for the production of green biodiesel with Azadirachta indica seed oil to promote the circular economy

Abstract

In this study, waste eggshell (WES) has been used to manufacture a heterogeneous Cu-CaO catalyst and used for Azadirachta indica seed oil straight transesterification. The catalyst is made via wet impregnation, which produced a crystalline structure having an area on the surface of 4.8893 m²/g and on average, the size of the pores 275.826 Å, as measured by XRD and BET measurements. The composition of the Cu-CaO catalyst is further verified by SEM-EDS analysis. The direct transesterification process has been optimized by modifying the catalyst dosage (%), reaction temperature (°C), ethanol mole ratio, and time (min). At a catalyst quantity of 9% wt/wt, 3 h response duration, 12:1 Ethanol to oil mole proportion, and 65°C temperature, the maximum yield of Methyl Ester of Fatty Acid (90%) is obtained. In addition, a number of characteristics of the produced biodiesel are measured, including cloud point 9°C, pour point 4°C, higher heating value 38.86 MJ/kg, acid value 0.32 mg KOH/g, density 0.8553 g/cm³, kinematic viscosity 5.10 cSt, and moisture content 0.03. After six cycles, the Cu-CaO catalyst's stability and reusability are established. These results show that eggshell waste-derived Cu-CaO catalyst has the potential to be an affordable, sustainable and environmentally friendly catalyst for the synthesis of biodiesel.