Biodiesel Production from Jatropha curcas L. Oil by Transesterification with Hexane as Cosolvent

An attempt to speed up the production process of biodiesel from Jatropha curcas oil through a cosolvent-assisted transesterification reaction was performed. The NaOH-catalyzed methyl ester production aided with hexane as cosolvent was systematically optimized in terms of four process variables: cosolvent to methanol volumetric ratio, methanol to oil molar ratio, amount of catalyst with respect to the amount of oil, and reaction temperature. Reaction products were determined by thin layer chromatography (TLC) and quantified using the BIOSOFT Quantiscan software. Based on the legislated minimum methyl ester purity of 96.5% as criteria, the optimum cosolvent to methanol volumetric ratio was 2:5. The optimum methanol to oil molar ratio of 8:1 was the best ratio considering process economics. The optimum amount of catalyst as mass percentage of oil mass was 1%. When carried out at ambient temperatures (25-30 degrees C), the legislated minimum methyl ester purity of 96.5% may be achieved in about 10 min of reaction; at a temperature (60 degrees C) near the boiling points of both hexane and methanol, the legislated minimum methyl ester purity can be achieved in only about 7 min of reaction, i.e. way below the usual 1 hr reaction period in conventional transesterification methods. Fuel properties (flashpoint, kinematic viscosity at 40 degrees C, sulfated ash, copper strip corrosion, cloud point, free glycerin, and total glycerin) of biodiesel produced using the optimum process variables meet the requirements of the Philippine National Standards (PNS) for biodiesel.