Properties and emission indicators of biodiesel fuels obtained from waste oils from the Turkish industry

Three waste oils from traditional manufacturing industries in Turkey, such as leather fat, obtained as a by-product in the leather industry, waste anchovy fish oil, derived from the fish-processing industry, and waste frying cottonseed oil from food industry, have been evaluated as alternative raw materials for biodiesel production, with potentially low life-cycle greenhouse emissions. Measured properties such as heating value, density, viscosity, flash point, acidity and cold flow properties, showed that the obtained biodiesel fuels fulfilled both the European and American quality standards and could be used to partially replace petroleum diesel in automotive engines. From gas chromatography analysis, detailed fatty acid profile was obtained, which permitted the application of group contribution methods for the estimation of thermodynamic properties (critical parameters, acentric factor) and thermochemical properties (enthalpies of vaporization and formation). This information was useful to calculate some indicators related to the most important diesel engine emissions, such as soot (main component of particulate matter) and nitric oxide emissions. Soot indicators reveal significant reduction potential with respect to fossil diesel fuels, and, among the studied biodiesel fuels, soot emissions would be lowest for the most saturated and shortest carbon-chain length biodiesel fuel. Adiabatic flame temperature, selected as the main nitric oxide emission indicator, shows small differences among the studied biofuels. Both the properties and emission indicators of the biodiesel fuels studied are within the typical ranges of other conventional biodiesel fuels.