Influence of Bacillus pumilus on the corrosivity of Biodiesel obtained from Jatropha curcas

Abstract

Environmental concerns over worsening air pollution problems caused by emissions from vehicles and depletion of fossil fuels have forced us to seek alternative fuels such as biodiesel which can supplement petrofuels Numerous feedstocks like soybean oil sunflower oil corn oil rapeseed oil castor oil and used cooking oils are used for biodiesel production Because of high oil content adaptability to harsh climatic conditions and nonedibility Jatropha curcas is one of the promising feedstocks used for the production of biodiesel in India Though biodiesels are renewable and have numerous advantages their inherent characteristics like thermal instability water absorption and oxidation cause difficulties for transportation, storage as well as in their use Biodiesels being fatty acid methyl esters have the ability to retain water and provide a conducive environment for the growth of microorganisms The presence of microorganisms will lead to one of the important corrosion types called microbiologically influenced corrosion MIC Knowledge about the microflora of the biodiesel will provide a clear idea about the corrosion problems encountered while handling biodiesel Hence for the present work the bacteria present in the 2 year old stored Jatropha curcas biodiesel were isolated and influence of the bacteria on the corrosivity of biodiesel on metals was investigated The isolated bacteria were identified as Bacillus pumilus The influence of bacteria on the corrosion of newlinemetals by jatropha biodiesel was studied using mass loss measurements and electrochemical studies The results revealed that even though Bacillus pumilus accelerated corrosion of metals in various test matrices it has also inhibited corrosion of metals in different test matrices The surface morphology of the metal samples subjected newlineto mass loss measurements were analysed by optical microscopy laser profilometry and SEM analysis The results reveal that the corrosion rates of ferrous metals were found to be higher compared to non ferrous metals In brass Bacillus pu