Original Articles: 2013 Vol: 5 Issue: 2
Storage stability of fatty acid methyl esters from Hevea brasiliensis
Biodiesel is a fast emerging alternate fuel but with its own disadvantage of having limited oxidative stability. Fatty acid methyl esters (FAMEs) obtained from high acid value (46.41 mgKOHg-1) rubber seed oil (RSO) was characterized by GC-MS and 1H-NMR. Fuel properties analysed were found to fit the required ASTM D6751 standard. Moreover, the possibility of monitoring the conversion efficiency of RSO to its corresponding methyl esters using FT-IR and NIR techniques was also analysed. As an important specification of bio-fuel quality, the fuel must have a minimum of three hours of oxidative stability (110oC) as per ASTM D6751 standard. Influence of metal contaminants, air, moisture and light on oxidative stability was studied on biodiesel having high iodine value. Acid value, peroxide value and induction period were recorded for samples under six different environments such as open (light exposed), closed (light exposed), open (dark), closed (dark), open (metal contaminated) and closed with metal contamination. Significant impact was observed only when metals are present as contaminants. Extent of degradation (oxidation) is higher when the samples are contaminated by metals, limiting the storage stability to thirty days. Higher oxidative stability was achieved under dark in the closed environment but in the absence of any metal contaminant.