Influence of metal contaminants on oxidation stability of Jatropha biodiesel

According to proposed National Mission on biodiesel in India, we have undertaken studies on stability of biodiesel from tree borne non-edible oil seeds Jatropha. European biodiesel standard EN-14214 calls for determining oxidation stability at 110 degrees C with a minimum induction time of 6 h by the Rancimat method (EN-14112). Neat Jatropha biodiesel (JBD) exhibited oxidation stability of 3.95 h and research was conducted to investigate influence of presence of transition metals, likely to be present in the metallurgy of storage tanks and barrels, on oxidation stability of Jatropha methyl ester. It was found that influence of metal was detrimental to oxidation stability and catalytic. Even small concentrations of metal contaminants showed nearly same influence on oxidation stability as large amounts. Copper showed strongest detrimental and catalytic effect. The dependence of the oxidation stability on the type of metal showed that long-term storage tests in different types of metal containers for examining the influence of container material on oxidation stability of biodiesel may be replaced by significantly faster Rancimat test serving as an accelerated storage test. (C) 2009 Elsevier Ltd. All rights reserved.