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| News Releases & Research |
Jatropha Research:
- Extraction of Jatropha Oil: A Comparison of Different Solvents
- Jatropha Soap: A Comparative Study
- Ethanol from Jatropha cake
- Oxidative Stability of Jatropha Oil
1. Extraction of Jatropha Oil: A Comparison of Different Solvents
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:
Fig. 1: Quantity of extracted oil |
Fig. 2: OD for Jatropha extracts and controls |
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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.
2. Jatropha Soap: A Comparative Study
Jatropha soap was synthesized by the saponification processes using jatropha oil and sodium hydroxide as the base. Several properties of the soap were investigated and compared to three other soaps. The jatropha soap compared very well with the commercially available soaps. It was noted the jatropha soap was better than the other soaps in the action/ solubility of hard water, and the antibacterial activity. The table below indicates the results of the evaluation.
3. Ethanol from Jatropha cake
The Jatropha Caucus produces seeds that have up to 37% oil content. This oil is extracted by either solvent extraction or screw press. After extraction, the Jatropha seed cake has been used as manure in the farms. The purpose of the project was to use the jatropha cake in an attempt to produce ethanol through anaerobic fermentation in the presence of yeast. The contents of fermentation were subjected to distillation at 800C in a water cooled distillation column. The distillate was collected and compared with the commercial ethanol using the iodine test.
Ethanol was successfully produced from the Jatropha cake through yeast fermentation and separation by distillation. The ethanol test for the prepared samples compared well with the commercially available ethanol. The table below shows the process involved.
More research should be carried out using other types of microbes like Zymomonas mobilis, a bacterium that is notable for its bio-ethanol producing capabilities, which surpass yeast in some aspects.
4. Oxidative Stability of Jatropha Oil
The objective of the study was to determine the oxidative stability of jatropha oil which is the measurement of the oil’s ability to withstand natural degradation. The factors that affect the oxidative stability of jatropha oil were evaluated using refined jatropha oil. These include the effect of heating, moisture, un-saturation and free fatty acid content. Levels of moisture content, acid value, and the iodine value were determined. In addition, biofuel chemical additives such as IRGASTAB BD 100 and food/oil antioxidant tertiary-butylhydroquinone (TBHQ) were used to investigate ways of retarding the oxidation process in Jatropha Oil. Wijs titration method was used to determine the iodine value while titration with sodium hydroxide was used to determine the acid value (isopropyl alcohol used before titration). The moisture content was found to be 0.22 %. The iodine and acid values increased after heating but decreased significantly after adding the additives. The IRGASTAB BD 100 had the best results in lowering both the acid and iodine values.
The study concludes that under normal conditions of temperature, moisture and oxygen levels, the jatropha oil will remain stable. If subjected to high temperatures in the presence of moisture and oxygen for prolonged period of time, degradation will take place.
It was also predicted that the increase in iodine value after heating may be due to the formation of trans-4-hydroxy-2-nonenal (HNE), a compound that contains double bonds formed by unsaturated vegetable oils when heated at frying temperatures.
Source: Research Unit, Kimminic Corporation, Dr. R. Kahama |
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