The purpose of the project was to compare the extraction of jatropha oil using three different solvents: hexane, ethyl acetate and ethanol. This was to explore whether any of them would be a suitable alternative to the hexane which is the fossil fuel most commonly used in jatropha oil extraction. Spectrophotometric measurements were used to assess purity of oil extracted.

The ethyl acetate and hexane extracted oils were comparable in quantity and quality. The amount of oil extracted with ethyl acetate was 1.9 g per 10 mL of solvent, while hexane had 2 g per 10 mL of solvent. The Optical Density (OD) test also revealed the comparability of ethyl acetate and hexane as solvents; the OD of Jatropha ethyl acetate was 0.277 at 600 nm and the OD of Jatropha hexane was 0.254 at 600nm. These results are illustrated in figures 1 and 2 below:

Ethanol, however, may not be acceptable as an alternative to hexane, as it was very difficult to remove from the oil once the extraction experiment was complete. This may be due to the fact that ethanol is able to extract other organic compounds, resulting in highly impure oil and making filtration very difficult. The final amount of oil after evaporation of the solvent was 0.5 g per 10 mL of solvent. Jatropha ethanol mixture had a tendency to foam during pipetting, indicating dissolved impurities, and results from the OD test of Jatropha ethanol also showed many impurities in the oil. The OD number was 0.693 at 600nm, more than twice that of Jatropha ethyl acetate and Jatropha hexane.

Ethyl acetate, however, is an acceptable alternative to hexane as it yielded a comparable amount of oil, and is possibly a more natural and sustainable method of jatropha oil extraction. An alternative to hexane in extraction should be considered for two main reasons: first, hexane is a fossil fuel, the second largest component of natural gas next to methane. Secondly, the United States Environmental Protection Agency (EPA) now considers hexane a hazardous air pollutant (HAP). It is monitored and regulated under the Toxic Release Inventory (TRI) Program of the EPA.

More research is required in this area to perform qualitative and quantitative analysis of jatropha oil based on ethyl acetate solvent extraction in a large scale setting; then develop the extraction method further for commercial purposes.

Source: Research Unit, Kimminic Corporation, Dr. R. Kahama