Caracterização e estabilidade térmica de biodiesel de óleo de fritura.

Abstract

Biodiesel derived from the frying oil contributes to a reduction of greenhouse gases in the atmosphere and minimizes the disposal of waste oil into the environment. This workmaims to characterize and evaluate the thermal stability of alkaline transesterification of biodiesel from the frying oil routes methyl and ethyl. The samples were characterized through physicochemical, spectroscopic, chromatographic and thermal analysis. In the process of getting the biodiesel from frying oil, the reaction rate and methyl ethyl routes were 95% and 94% respectively. The physicochemical properties indicated that all parameters for methyl and ethyl biodieseis from the frying oil met the demands of the limits established by the Technical Regulation No. 1 / 2008 of the National Agency of Petroleum, Natural Gas and Biofuels (ANP), except ester content. The chromatographic data confirmed the conversion of used frying oil into esters, indicating conversion to ester content of 90.1 % of biodiesel methyl, below the limit established by the Technical Regulation of ANP (96.5%), indicating the need to improve the synthesis process. The infrared spectra showed the main absorption bands of methyl and ethyl biodiesel from used frying oil and their respective functional groups and show that both biodieseis showed low humidity. Thermogravimetric curves (TG) of samples of frying oil biodiesel showed two stages of mass loss attributed to the processes of volatilization and/or decomposition of esters, particularly their major components linoleate and oleate indicated by chromatography. Comparing the samples it appears that biodiesel methyl was more stable than the ethyl biodiesel. Biodiesel methyl remained thermally stable up to 143 0 C ethanol and biodiesel to 122 ° C. The curves of differential thermal analysis (DTA) of biodieseis observed four exothermic transitions attributed to the combustion process of the esters. Although derived from frying oil waste, the methyl and ethyl biodieseis showed satisfactory results regarding the characterization and thermal stability.