An experimental investigation into biodiesel stability by means of oxidation and property determination

This paper presents the experimental results carried out to evaluate the oxidation and storage stabilities of various biodiesel fuels. The biodiesel fuels are palm methyl ester (PME), jatropha methyl ester (JME), coconut oil methyl ester (COME), 20% blends of PME with diesel fuel and 20% blends of JME with diesel fuel. The ordinary diesel fuel was used for comparison purposes. Various ASTM standard methods were used to evaluate all the samples at the interval of 180 h over a 2160 h (three months) duration. Oxidation stability of the samples was measured by induction period (IP) using a Rancimat instrument. Other properties such as density, viscosity, flash point, total acid number (TAN), and total base number (TBN) were measured. The results show that almost all fuel samples met the standard specifications regarding IP. The trends for density, viscosity and TAN increased, while the TBN decreased due to oxidation. For the flash point, the trend also decreased, but the rate was very low. In overall consideration, among the biodiesels, COME was found to be better in respect to oxidation and storage stabilities. The results of this investigation will be used to sustainable development of biodiesel fuel from various stock resources.