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United States Department of Agriculture

Agricultural Research Service

Title: Spectroscopic Means for Assessing Biodiesel Fuel Quality

Author
item Knothe, Gerhard

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: May 13, 1998
Publication Date: N/A

Technical Abstract: Biodiesel is defined as the mono-alkyl esters of a vegetable oil or animal fat. It is usually produced by transesterification of a vegetable oil, such as soybean oil, or animal fat with an alcohol, usually methanol, in presence of a catalyst such as KOH. The products have commonly been analyzed by gas chromatography for the residual feedstock, glycerol, alcohol as well as mono- and diglycerides. The analysis by gas chromatography, which also requires a derivatization reaction, may be too slow for some production processes. Near infra-red (NIR) spectroscopy, on the other hand, has provided fast, reliable, and instrumentally uncomplicated analyses of materials in fats and oils chemistry. In the present work, the application of NIR spectroscopy to the transesterification process as applied in biodiesel production was explored. NIR spectra were obtained by means of a fiber-optic probe, which further facilitates analysis. NIR spectroscopy was investigated for analyzing the transesterification reaction for the product, the feedstock, the alcohol (methanol), and contaminants such as glycerol, moisture, free fatty acids, and mono- and diglycerides. The possibility of using the NIR spectroscopic method for evaluating an ester product in terms of guidelines for pending biodiesel standards was explored.

Last Modified: 7/24/2014
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