Optimized production and advanced assessment of biodiesel: A review

Biodiesel production is profitable only under special conditions. Technical challenges including methods to make the transesterification reaction more energy efficient and faster by using catalysts, controlling reaction conditions more efficiently in narrow range, or selection of appropriate feedstocks should be properly addressed to make biodiesel economical viable fuel. Cradle to grave assessment of biodiesel is provided in the present review article. Transesterification reaction variables that affect the purity and performance of biodiesel including quality of raw materials, molar ratio of alcohol to oil, type and concentration of used catalysts, concentration of free fatty acids, water content, temperature, and time required for the reaction are critically described to provide complete understanding and obtaining economical and optimal biodiesel yields. This article also provides a critical review of biodiesel properties such as density, viscosity, cetane number, cloud point, pour point, and flash point. The importance of analytical methods including gas chromatography, high-performance liquid chromatography, nuclear magnetic resonance spectroscopy, infrared spectroscopy, and Raman spectroscopy is presented and highlighted here in a novel way. Finally, this review will provide complete understanding to readers about biodiesel.