Cholakov G.Yanev S.Markov V.Stoyanov S.2024-07-162024-07-162024-07-162024-07-162013-11-051314-74711314-7978SCOPUS_ID:84886736257https://rlib.uctm.edu/handle/123456789/1010Extracts from secondary biomass, e. g. spent coffee grounds (SCG), can be utilized in the production of biodiesel additives (esters of fatty acids with low molecular mass alcohols). However, they contain a significant amount of free fatty acids, so the transesterification of their glycerides has to be preceded by catalytic esterification of these acids. SCG extracts are essentially a mixture of compounds with approximately equal amounts of glycerides with saturated and unsaturated fatty acid moieties, so their iodine values are much lower than those of the typical highly unsaturated biodiesel feedstocks - e.g., sunflower oil, soybean oil, etc. In the wider context of our studies on the preparation of renewable fuel additives from SCG and other extracts from secondary biomass, this work presents results on direct esterification of mixtures of pure fatty acids, modeling the unsaturation of such extracts. They are also relevant to the utilization of biodiesel feedstocks, consisting entirely or predominantly of fatty acids like tall oil, soapstock and synthetic fatty acids, etc.enArticle