In this study, proton NMR spectroscopy (200 MHz) was used for quantifying the content of ethyl esters in known mixtures of soybean oil and ethyl soyate (biodiesel). For this purpose, the peak areas of ester ethoxy and glycerol methylenic peaks in the region of 4.05-4.40 ppm were measured and a calibration plot of the respective peak areas vs. the known composition of the oil/ethyl ester mixtures was used. The transesterification values determined in this way were compared with viscosity and total glycerol determinations and a good correlation was obtained. Therefore, for routine analysis, the conversion (in %) of oil to ethyl esters was determined. The methodology presented in this work proved to be quicker and simpler than others reported in the literature, such as GC and/or HPLC.
Neste trabalho verificou-se a eficiência de diferentes adsorventes na purificação de óleo de soja usado em frituras. Foi verificado, igualmente, a eficiência de mistura de carvão ativo, tonsil e bauxita na purificação de óleo que havia sido utilizado por 18, 40, 68 e 79 h. A reativação e reutilização da mistura adsorvente também foi testada e mostrou-se viável.
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