Rapid and low-temperature biodiesel production from waste cooking oil: Kinetic and thermodynamic insights using a KOH/ZnAl2O4 nanocatalyst derived from waste aluminum foil

This study aims to explores the catalytic potential of potassium hydroxide loaded on zinc aluminate (termed as KOH/ZnAl2O4), a novel heterogeneous catalyst, for the swift and efficient production of biodiesel from waste cooking oil (WCO) at low time and low temperature. Utilizing aluminum foil waste (AFW) as a precursor, environmentally friendly zinc aluminate (ZnAl2O4) is synthesized and loaded with KOH, to enhance the feasibility of transesterification biodiesel processes and contribute to environmental sustainability. The catalyst is thoroughly characterized through various analytical techniques, including XRD, FT-IR, BET isotherm, CO2-TPD, SEM-EDX, and AFM. Systematic parametric studies identify optimal transesterification conditions: 4 % wt. catalyst loading, 90 min reaction time, and a 9:1 methanol to oil molar ratio (MTO-MR). Under these conditions, an exceptional biodiesel conversion rate of 95.3 % is achieved. These optimal conditions outperform comparable catalysts, affirming the reliability of this catalyst for environmentally friendly, commercially viable biodiesel production. Kinetic and thermodynamic analyses reveal activation energy (Ea), activation enthalpy (Delta H#), and activation entropy (Delta S#) values of 42.57 kJmol- 1, +40 kJmol- 1, and -147.9 Jmol- 1 K- 1, respectively. The catalyst exhibits sustained activity over six successive cycles. Additionally, the physicochemical properties of the produced biodiesel adhere to international standards (ASTM D-6751 and EN-14,214), endorsing the proposed catalyst as a robust option for industrial biodiesel manufacturing.