Biodiesel Production from Jatropha curcas (l.) Seed Oil Using a Green-Synthesized MGO Nanocatalyst and RSM Method for Optimization
Kingsley E. Apuyor *
Department of Chemistry, Dennis Osadebay University, Asaba, Delta State, Nigeria.
Augustine K. Asiagwu
Department of Chemistry, Delta State University, Abraka, Delta State, Nigeria.
Charles Otobrise
Department of Chemistry, Delta State University, Abraka, Delta State, Nigeria.
Stanley E. Apuyor
Department of Industrial Chemistry, Dennis Osadebay University, Asaba, Delta State, Nigeria.
Augustine Apuyor
Department of Research Outreach, National Cereals Research Institute, Badeggi, Nigeria.
*Author to whom correspondence should be addressed.
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.
Keywords: Jatropha curcas, MgO nanocatalyst, green synthesis, transesterification, response surface methodology, biodiesel