Determination of Oxidation Stability of Palm-Oil Biodiesel and Biodiesel-Diesel Blends by Rancimat and RSSOT Methods

Abstract

Determination of oxidation stability becomes a critical fundamental analysis to ensure biodiesel quality. The biodiesel’s degradation by oxidation may compromise fuel properties and engine durability due to forming products of fatty acid decomposition. In this present study, the oxidation stability of palm-oil biodiesel and its blends with diesel fuel (cetane number 48) was determined using EN 15751 (Rancimat Method) and ASTM D 7545 (Rapid Small Scale Oxidation Test, RSSOT Method). Here, the determination from either test was compared and analyzed using ANOVA and the mathematical function. Based on the result, diesel fuel has oxidation stability 11 times higher than palm-oil biodiesel, analyzed by the RSSOT method. Additionally, the correlation factor of oxidation stability of biodiesel samples in this work was 21.52 and for biodiesel blend (B20 to B90) it was 23.66 that was used as a conversion oxidation value between RSSOT and Rancimat method. The models presented a high correlation with the R2 values of 0.9535 for biodiesel samples and 0.9823 for biodiesel blend (B20-B90) indicated the accuracy of the models to predict the value of oxidation stability of both the Rancimat and the RSSOT accelerated oxidation methods.