Evaluation of quality items for biodiesel made from three kinds of Chlorella vulgaris

Abstract: In order to evaluate the quality items of microalgae biodiesel which has the potential to be exploited, this paper evaluated three kinds of Chlorella vulgaris biodiesel, providing a theoretical foundation for choosing an appropriate biodiesel Chlorella vulgaris species to produce biodiesel. Compared to petro-diesel, biodiesel has many advantages: higher biodegradability, lower sulphur content, lower carbon dioxide emission, no aromatic hydrocarbon, and lower flash point which makes the usage, transportation, management, and storage much safer. As a source of raw material for biodiesel production, oil productive Chlorella vulgaris commands high attention because of many strengths such as taking up less cultivated area, high growth rate, high oil-production efficiency, and renewability. The direct determination of biodiesel quality items is time wasting and costly, and for not yet industrialized microalgae cultivation, it is hard to acquire sufficient quantities of microalgae biodiesel. Through precursors' mathematical model between biodiesel FAME(fatty acid methyl ester) carton chain structure and Vis(viscosity), IV(iodine value), CN(cetane number), CFPP(cold filter plugging point), compared to the biodiesel standards of America、EU、Germany and China of Vis, IV, CN, CFPP, the Chlorella vulgaris biodiesel quality items can be indirectly forecasted. This paper through analysis of the oil content and the constituting of FAME which is made from oils in three kinds of oil productive Chlorella vulgaris cells, makes use of the established mathematical model between FAME carbon chain structure and biodiesel quality items, by reference to biodiesel standards of America、EU、Germany and China, and assesses the biodiesel quality items concluding Vis, IV, CN and CFPP of Chlorella vulgaris F-5,F-1067,F-31 biodiesel. The results show that: the oil contents of Chlorella vulgaris F-5,F-1067,F-31 are 15.30%，13.13%，and 11.12%. The Vis of F-5 biodiesel is 8.3, which can meet the standards of America and China, but can't meet the standards of the EU and Germany, The IV、CN、CFPP of F-5 biodiesel are 77，56，-3℃ which can all meet the standards of America、the EU、Germany, and China; The Vis and CFPP of F-1067 biodiesel are 9.2 and 9℃ which can't meet the standards of America、the EU、Germany and China, The IV and CN of F-1067 biodiesel are 77 and 56 which can all meet the standards of America、the EU、Germany and China; The Vis of F-31 biodiesel are 11.8 which can't meet the standards of America、the EU、Germany, and China, The IV and CFPP of F-31 biodiesel are 112 and -9℃ which can meet the standards of America、EU、Germany, and China, the CN of F-31 biodiesel is 47 whih can meet meet the standard of America, but can't meet the standards of the EU、Germany and China. So F-5 had the highest oil content, more than that, its comprehensive performance in Vis、IV、CN、 CFPP was better than the other two, and it is the best fit to produce biodiesel in the three oil-productive Chlorella vulgaris. In addition, the method which this article used to evaluate the quality items for biodiesel made from three Chlorella vulgaris is quick, time-saving, economical, and convenient. It also supplies a method for a large number of species of microalgae screening as to whether they have potential for microalgae biodiesel production or not. Although the microalgae has great potential to produce biodiesel, at the present, the usage of microalgae to produce biodiesel still has a long way to go, because of its high cultivation cost, harvest cost, drying cost, and oil-extract cost. More effort needs to be exerted to do more research about it.