Production of Hybrid Biodiesel from a Novel Ternary Oil Blend: Dual-Stage Process Optimization Using Desirability-Based RSM

The production of biodiesel is increasingly recognized as a sustainable alternative to fossil fuels. This study explores a two-step process for biodiesel production using a blend of Neem oil, Shea butter, and Waste kitchen oil. Process optimization was conducted using response surface methodology and the superposition approach, focusing on temperature, reaction time, ethanol-to-oil ratio, and catalyst concentration to maximize biodiesel yield. The model's performance was evaluated through R² and Absolute Average Deviation values. The highest desirability values obtained were 1 and 0.99 for the esterification and transesterification stages, respectively, with corresponding conversion yields of 94.57% and 90.53%. The analysis of the biodiesel revealed the presence of four distinct ethyl esters that are consistent with common fatty acid ethyl esters found in biodiesel. The hybrid biodiesel produced meets international standards, including ASTM and EN. Furthermore, the study achieved a high biodiesel yield with minimal catalyst usage (0.52 wt.%) and a short processing time (30 minutes), highlighting industries' potential to improve biodiesel production's economic viability by adopting similar optimized conditions.