ARS | Publication request: Spectroscopic Methods for Determining the Oxidation of Biodiesel Fuel

Submitted to: Meeting Abstract
Publication Type: Proceedings/Symposium
Publication Acceptance Date: September 28, 2002
Publication Date: N/A

Technical Abstract: Mono-alkyl esters (usually methyl esters) of vegetable oils and animal fats are achieving increasing significance as alternative diesel fuel, in which case they are called biodiesel. As the fatty acid chains of the original vegetable oil or animal fat are retained in biodiesel, the reactions these chains can undergo are similar to those of the parent oil or fat. Therefore, stability of biodiesel upon exposure to air, especially during storage, is a significant technical issue facing this fuel. This oxidation can lead to fuel deterioration and eventually to performance problems. Besides improving this property of biodiesel, analytical methods for assessing the quality of stored biodiesel fuel relative to its potential oxidation need to be developed. Most previous analyses in this area have utilized wet chemical methods (for example, peroxide value) or determination of physical properties (for example, viscometry). Based on previous work using spectroscopic methods for assessing biodiesel quality relative to the production process and possible contaminants, these methods are now extended to determining the quality of stored biodiesel. The spectroscopic methods are near-infrared (NIR) spectroscopy using a fiber-optic probe and **1H-nuclear magnetic resonance (NMR). For that purpose, methyl soyate was heated under bubbling of air and samples taken at certain intervals. The samples were analyzed by the spectroscopic methods as well as other methods such as viscometry and the results correlated.