Bimetallic Nanoparticles on Eggshell-Derived CaO Catalyst for Efficient Biodiesel Production

Abstract

The transformation of agricultural waste into an effective catalyst will not only provide clean energy but also help to minimize waste disposal issues. In this study, leftover eggshell powder was calcined at 900 oC to make CaO powder, which is then incorporated with Ag and Cu nanoparticles synthesized through a green route by utilizing polyalthia lonfifolia plant extract. Four catalysts categorized as CaO, Ag/Cao, Cu/CaO, and Ag-Cu/CaO were prepared and utilized in the transesterification reaction separately. Rice bran oil was utilized to make FAMEs by employing these four catalysts separately. The prepared catalysts were characterized by XRD, FTIR, TGA, and SEM, while BET (for Ag-Cu/CaO only) was used to assess the catalysts’ crystalline shape, structural changes upon doping. The bimetallic doped heterogeneous nano-catalyst (Ag-Cu/CaO) provided a maximum biodiesel yield 99% at optimum reaction conditions (oil to methanol 1:9, reaction time 3hr, temperature 65 oC, catalyst loading 3 wt%). The single doped catalyst, such as Ag/CaO, provided 92% apparent biodiesel yield, Cu/CaO provided 93% yield at optimum conditions. The undoped CaO nano-catalyst offered a lower biodiesel yield of only 88% at optimum conditions. The biodiesel prepared by utilizing Ag-Cu/CaO nano-catalyst at optimum conditions was assessed by GC-MS for the confirmation of FAMEs preparation. In addition to this, biodiesel characteristics such as Cloud point, pour point, Flash point, and density were also investigated and compared with ASTM D6751 standards. The apparent biodiesel yield and parametric studies were utilized to evaluate the catalytic effectiveness of CaO, Ag/CaO, Cu/CaO catalysts in the transesterification reaction for biodiesel production.