"Production of biodiesel, in a continuous flow reactor, from cotton oil under supercritical conditions."
Biodiesel; Cottonseed Oil; Gossypium hirsutum L.; Transesterification; Interesterification; Supercritical.
In the global energy context, biodiesel has emerged as an important source of renewable energy, mainly due to its ease of production and the variety of raw material available worldwide. Specifically in Brazil, the biodiesel industry has shown significant growth in production, due to the federal laws that require the mixing of B100 (biodiesel) with fossil diesel. Considering the importance of this industry to Brazil, this work sought to evaluate the potential of cotton seed oil for biodiesel production from three techniques: transesterification using ethanol, interesterification (using methyl acetate) and interesterification with methyl acetate and addition of aqueous acetic acid solution. The reactions occurred under supercritical conditions of temperature and pressure, in a continuous flow tubular reactor, with a volume of 15 mL. The maximum yield obtained by the transesterification was 75.05%, at the pressure of 150 and 200 bar, 375 °C, oil/ethanol molar ratio 1:40, and residence time 40 and 30 min, respectively. On the route using methyl acetate the highest yield was 99.51% (FAME (fatty acid methyl esters) + triacetin), obtained in 35 min, oil/methyl acetate ratio 1:3, pressure 200 bar and 350 °C using 20% aqueous acetic acid solution (26%). High values of biodiesel decomposition were observed in both routes due to the high concentrations of polyunsaturated triglycerides in the oil and the severe process conditions.