Microwave-assisted biodiesel production from waste cooking oil using pyrrolidonium ionic liquid catalyst: optimization, kinetic and thermodynamic studies

Biodiesel production from waste cooking oil (WCO) has been gaining popularity due to its economical and ecofriendly nature. This study aimed to produce an environmentally friendly fuel by recycling WCO. Using pyrrolidonium-based Br & oslash;nsted acidic ionic liquid (IL) as a catalyst, microwave-assisted transesterification of WCO was used to produce biodiesel. Reaction conditions, including temperature, catalyst amount, methanol/oil molar ratio, and reaction time, were optimized using response surface methodology (RSM) based on Box-Behnken design (BBD). A biodiesel conversion of 97.3 % was achieved at 115 degrees C, for 120 min, with 10 % catalyst loading, and a 24:1 methanol/oil molar ratio. The kinetics of the transesterification reaction was investigated, with the activation energy determined to be 13.67 kJ mol-1. The thermodynamic values were also calculated, Delta H = 10.6 kJ mol-1, Delta S =- 252.53 J mol-1 K-1 and Delta G = 99.7-109.8 kJ mol-1. Thus, the microwave-assisted transesterification reaction was endothermic, endergonic, and non-spontaneous. The IL catalyst demonstrated excellent reusability, maintaining high activity for six consecutive cycles. In addition, the quality of WCO biodiesel met the ASTM D6751 standard. Pyrrolidonium-based ILs are effective catalysts for biodiesel production owing to their recyclability, catalytic stability, and eco-friendly characteristics.