Kinetics and thermodynamic analysis of transesterification of waste cooking sunflower oil using bentonite-supported sodium methoxide catalyst

The current study concentrates on chemical kinetics, thermodynamic, and overall mass transfer studies on production of biodiesel from waste cooking sunflower oil in transesterification reaction using bentonite-supported sodium methoxide catalyst. The kinetics and thermodynamics analysis of biodiesel from waste cooking sunflower oil was studied at three different temperatures, namely, as 50, 55, and 60 degrees C using bentonite-supported sodium methoxide catalyst at optimized conditions of methanol-to-oil molar ratio of 12:1 and reaction time of 70 min. It was found that transesterification of waste cooking sunflower oil follows the first-order reaction. The calculated activation energy and pre-exponential factor were found to be 40.98 kJ mol(-1) and 1.4 x 10(5), respectively. The positive values of Gibbs free energy ( increment G = 89.66 kJ mol(-1)), enthalpy ( increment H = 38.05 kJ mol(-1)), and negative entropy ( increment S = - 0.15 kJ K-1 mol(-1)) values revealed that the transesterification process is non-spontaneous and endothermic in nature. The reaction rate is a function of two resistances: the surface chemical reaction on the catalyst surface and the mass transfer of triglycerides to the catalyst. The overall calculated parameters of triglyceride volumetric mass transfer coefficient, k(mt,TG) is 1.18 x 10(3) min(-1), and effective pseudo-first-order reaction rate constant, k, is 0.0525 kJ mol(-1) min. The used kinetic model accurately represents the entire transesterification mechanism, involving triglyceride conversion to fatty acid methyl ester (FAME) and reaction-controlled on the catalyst. It is observed that the overall volumetric mass transfer depends mainly on the triglyceride conversion rate.

Automated summary

The study focused on the production of biodiesel from waste cooking sunflower oil using bentonite-supported sodium methoxide catalyst. It was found that the transesterification process is non-spontaneous and endothermic, with the reaction rate being affected by surface chemical reaction and mass transfer resistances.