Sustainable Biodiesel Production over a Novel Magnetic Solid Acid Catalyst Derived from Copper Ferrite: Statistical Optimization and Catalytic Performance Evaluation

Abstract In this study, a novel magnetic solid acid catalyst based on molybdenum oxide-impregnated copper ferrite was synthesized and applied to methyl transesterification from waste cooking oil (WCO). The catalytic solid was characterized by surface acidity, XRD, FTIR, SEM, EDS, and VSM techniques. A 24 face-centered central composite design (FCCD) and a linear regression mathematical model were developed to describe the behavior of the ester content of the biodiesel produced as a function of the independent reaction variables: temperature (120–180 °C); MeOH:WCO molar ratio (10:1–50:1); time (1–5 h); and catalyst concentration (2–10 wt %). The optimized experimental results yielded a biodiesel with 95.6% ester content under the following optimized reaction conditions: temperature of 155 °C, MeOH:WCO molar ratio of 35:1, catalyst concentration of 8 wt %, and reaction time of 3.5 h. The developed mathematical model exhibited a relative error of less than 5% between predicted and observed values, demonstrating its robustness. Furthermore, the catalyst exhibited excellent catalytic stability over four reaction cycles, with ester conversion remaining above 85%, indicating great reusability potential.