Author:
Castellanos Cuellar Isabel Cristina,Avella-Moreno Eliseo,Vargas-Molina Paula M.,Bejarano Andres M.
Abstract
To trace the production of biodiesel in a base-catalyzed transesterification of waste frying oils and methanol, mid infrared spectra were acquired by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) of the organic phases isolated from the reaction medium at 0, 5, 15, 30, and 60 minutes from the start of the process and analyzed qualitatively in comparison with the IR spectrum of the waste oil in its initial condition. Among all the signals or regions of the infrared spectrum proposed by other authors as suitable for monitoring the biodiesel content in blends, which were indeed observed in these ATR FTIR spectra, the signal at 1195 cm−1, attributable to the stretching of the bond between sp2 carbon and oxygen in methyl carboxylate -(CO)-OCH3 resulted in the most suitable signal to follow the biodiesel production in the reaction medium through the IR spectrum of the corresponding isolated organic phase. The signal at 1195 cm−1 appeared only in the infrared spectra of the organic phases containing some biodiesel, and its intensity increased steadily during the reaction. For the rest of the signals proposed in previous publications as useful for quantifying biodiesel in mixtures, it was demonstrated, by these infrared spectra, that there is interference by signals attributable to species, other than biodiesel, present in the mixture.
Publisher
Universidad Nacional de Colombia
Subject
History and Philosophy of Science,Physical and Theoretical Chemistry,General Physics and Astronomy,Geophysics,Electronic, Optical and Magnetic Materials
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