Research Article Comparative Studies of Oxidative Stability Properties of Biodiesel Produced from Azadirachta indica and

The aim of the study was to establish the stability of biodiesel due to oxidation. Two non-edible seed oils were used; Azadirachta indica and Hevea brasiliensis were used to produce biodiesel and first rapid oxidative stability of the biodiesel were assessed then their properties with and without additives compared thereof over a range of one year storage period. The results of stability of the biodiesels for rapid induction and long term period with and without additives revealed that physico-chemical properties of the biodiesel produced from Azadirachta indica and Hevea brasiliensis seeds oil changed with the time. For the rapid test, none of the biodiesel samples could pass the 6 hrs oxidation test with neem biodiesel exhibiting the best oxidation stability and the rubber seed the worst. Both the additives, namely 0.5 % tert-butyl hydroquinone (TBHQ) and 0.1 % Ecotive increased the oxidation stability of all the three biodiesel samples to more than 6hrs. The one year storage stability study revealed that per-oxide value, density, viscosity and acid number increased for all the methyl esters with time. However, the calorific value was found to be decreasing for all the samples. The rate of change of different physico-chemical properties was found to be less in case of all the biodiesel with an additive. However, Ecotive appeared to be a better additive as compared to TBHQ for increasing the shelf life of biodiesel