Biodiesel Production from Jatropha curcas (l.) Seed Oil Using a Green-Synthesized MGO Nanocatalyst and RSM Method for Optimization

Abstract

The growing demand for sustainable energy has intensified interest in biodiesel production from non-edible feedstocks. In this study, biodiesel was produced from Jatropha curcas seed oil via a two-step process involving acid-catalyzed esterification followed by MgO-catalyzed transesterification. The crude oil possessed a high free fatty acid (FFA) content of 6.80% (as oleic acid), necessitating a pre-treatment esterification step prior to base-catalyzed conversion. The esterification process effectively reduced the FFA content from 6.80% to 0.90%, corresponding to a reduction efficiency of approximately 86.8%, thereby making the oil suitable for subsequent transesterification. A green-synthesized magnesium oxide (MgO) nanocatalyst was prepared using Mangifera indica and Carica papaya leaf extracts via a solution combustion method. Process optimization was carried out using Response Surface Methodology (RSM) based on a Central Composite Design (CCD), considering ethanol-to-oil molar ratio, catalyst concentration, reaction temperature, and reaction time as independent variables. A quadratic regression model was developed and validated using analysis of variance (ANOVA). The optimal conditions were found to be an ethanol-to-oil ratio of 9:1, catalyst loading of 1.6 wt%, reaction temperature of 65 °C, and reaction time of 90 min, resulting in a maximum biodiesel yield of 82.05% (R² = 0.9936). The physicochemical properties of the produced fatty acid ethyl esters (FAEE) were generally within acceptable limits of ASTM D6751 standards. The results demonstrate that the green-synthesized MgO nanocatalyst is an efficient and environmentally friendly catalyst for sustainable biodiesel production from high-FFA Jatropha oil.