Optimization of Biodiesel Production from Jatropha and Waste Cooking Oil Blends Using Mixed Metal Oxide Nanocatalysts: A Response Surface Methodology Approach

Abstract

Biodiesel production has emerged as a sustainable alternative to fossil fuels, addressing both environmental concerns and the need for renewable energy. This study investigates the optimization of biodiesel production from underutilized vegetable oils, specifically jatropha seed oil and waste cooking oil, through transesterification using three synthesized nano-mixed metal oxide catalysts (n-CaO, n-CuO/CaO, and n-CaO/ZnO). A key challenge addressed is the inefficiency of conventional catalysts and the limited use of low-cost, sustainable feedstocks. Physicochemical analyses of crude, refined, and blended oils revealed improved fuel properties upon blending, notably a reduction in free fatty acid (FFA) content and acid value. Among the catalysts, CaO/ZnO exhibited the highest catalytic performance, achieving a biodiesel yield of 91.70 % and demonstrating strong stability over multiple reaction cycles. Optimization using a Full Factorial Design further improved the fatty acid methyl ester (FAME) yield to 94.76 %. Structural and functional analyses via FTIR and XRD confirmed the catalysts’ crystallinity and functional groups, while GC-MS identified key FAME components in the produced biodiesel. This comparative analysis of three nanocatalysts underscores their potential in enhancing biodiesel quality and yield, offering a scalable, ecofriendly solution for sustainable energy development.