Spectroscopic Studies of the Quality of Fatty Acid Methyl Esters Derived from Waste Cooking Oil

Biodiesel is a very attractive, biodegradable, renewable, and virtually nontoxic form of fuel. It is derived through base-catalysed transesterification of vegetable oils or animal fats. Analysis of biodiesel has become relevant, since the higher quality of the fuel is a key factor in commercialisation and market acceptance. The analytical methods employed are being constantly improved to meet this requirement. The most popular techniques for analysis of biodiesel include mainly chromatography and molecular spectroscopy. FTIR infrared spectroscopy is one of the most important spectroscopic techniques. The article presents the results of UV-Vis absorption spectroscopy and FTIR infrared spectroscopy analysis employed for investigating methyl esters of higher fatty acids obtained with laboratory methods from selected sunflower and rapeseed oils and waste animal fats provided by a slaughterhouse. Commercial methyl esters were included in the analyses for comparison. In all samples, the contents of free glycerol, methanol, esters, and linolenic acid methyl ester in FAME were determined mainly to facilitate the spectroscopic analysis. The results of the investigations conducted with the aforementioned methods clearly indicate that the analysed WCO esters can be successfully used as potential industrial-scale biofuels.