Biodiesel production by iron oxide supported on light weight expanded clay aggregate (Fe2O3-f-LECA) Catalyst: Box-Behnken design-based optimization and ANFIS modeling with GA and PSO

This study presents the synthesis of an iron oxide-supported functionalized lightweight expanded clay aggregate (f-LECA) catalyst via the microwave solution combustion method for biodiesel production. Characterization techniques, including XRD, FESEM, TEM, BET-BJH, and TPD-NH3, confirmed the uniform dispersion of iron oxide on f-LECA, leading to enhanced catalytic performance. BET-BJH analysis revealed a specific surface area of 8.35 m2/g, an average pore width of 10.47 nm, and a well-developed pore structure conducive to catalytic reactions. The catalyst exhibited strong acidity, as evidenced by ammonia desorption peaks at 346 °C and 390 °C, indicating the presence of medium-strength acidic sites essential for transesterification. A maximum biodiesel conversion of 96.47 % was achieved under optimized conditions: 100 °C, a methanol-to-oil molar ratio of 20, 3 wt% catalyst loading, and 1-h reaction time. Optimization using Response Surface Methodology (RSM) and Adaptive Neuro-Fuzzy Inference System (ANFIS) modeling demonstrated a strong correlation (R2 > 0.96) between predicted and experimental results. Further refinement using the Particle Swarm Optimization (PSO) algorithm enhanced model accuracy, yielding minimal error values based on MAE, MSE, RMSE, and R2 metrics. The excellent catalytic activity, economic feasibility, and environmental sustainability of f-LECA-supported iron oxide make it a promising candidate for large-scale biodiesel production from oleic acid.