Increasing the stability oxidation of palm oil biodiesel by the addition of binary antioxidant

Abstract

The need of fuel to support the availability of energy for the community continues to increase along with the increasing human population. On the one hand, fuel reserves such as petroleum are running low, therefore the development of renewable alternative fuels is required, one of which is biodiesel. The use of biodiesel has the disadvantage of oxidative instability due to its molecular structure, therefore it has the potential for degradation during the storage period. To minimize these deficiencies, addition of antioxidants is commonly applied. Antioxidant performance improvement is done by mixing two antioxidants to form synergistic binary antioxidant. In previous studies, it has been shown that mixing two antioxidants can improve the performance of antioxidants in maintaining the stability from biodiesel oxidation. However, the effect of oxidative stability to the biodiesel is dependent to the composition, and concentration of the binary antioxidant, as well as the variety of biodiesels. In this study, the properties of binary antioxidant heterodimers, relative to the palm oil biodiesel oxidation stability was observed over composition and concentration variation of the binary antioxidant. Antioxidants that were used in this study are combination BHA:BHT (1:1) and combination of TBHQ:BHT (3:1) that shown the highest increasing induction period to 21.86 and 22.5 hours respectively. The effect of antioxidant which increased the oxidation stability of biodiesel shown from the stability of acid value and iodine value. The acid value and iodine value that resulted from this study were kept within the specification of biodiesel (max. 115g-I2/ 100g for iodine value) and (max 0.5 KOH mg/g for acid value).