Introduction
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By: Samuel (Reuben) Gurupatham

As the world is becoming increasingly aware of environmental problems facing planet Earth, changes are starting to take place. Citizens and corporations are finding ways of reducing their carbon emissions and many governments are setting goals to reduce their country’s emission output. One solution to this problem is the use of biofuels such as Jatropha Oil.

Jatropha Oil is extracted from a plant and has the potential to be used as biofuel. Unlike other biofuels, like ethanol, Jatropha Oil is pressed from the seeds of a non-edible plant, which thrives in desert and semi-desert weather and soil conditions. Therefore it would not compete with human and animal food consumption and it would not require fertile land to be cultivated, like corn and wheat.

Jatropha Plant                          Jatropha Seeds                                 Jatropha Oil Press

Like all biofuels Jatropha Oil has a series of properties that set it apart from conventionally used fuels like diesel.

    Previously completed experiments by Reuben Gurupatham (2008) using Jatropha oil have shown promise in lowering the cloud point of Jatropha Oil with 17% chemical additive. The cloud point of this 17% additive and 83% Jatropha Oil solution was –110C. The calorific value of Jatropha Oil was increased significantly when combined with various proportions of ethanol. The most successful solution contained 50 % Ethanol and 50% Jatropha Oil.

    The oxidation stability of a fuel is another important chemical property. It is a measurement of a fuel’s ability to withstand natural degradation. Some affecting factors are temperature increases, contact with water and oxygen, unsaturation and high free fatty acid content. Oxidation starts to take place immediately after extraction. Although it can not be stopped, there are certain measures that can be taken to slow down the process. Companies such as CIBA Speciality Chemicals have developed additives that retard the oxidation process in biofuels. One of these chemicals is IRGASTAB BD 100 which has been proved effective on other biofuels such as Palm Oil. Antioxidants have recently shown promise in slowing down the oxidation process in oils as well. One of the more effective antioxidants is tertiary-butylhydroquinone (TBHQ). It is currently being used as a food preservative.

    Some factors that can help determine the oxidation stability of Jatropha Oil are the moisture content, acid value, and the iodine value. The moisture content of a fuel can prove to be a problem when protecting a fuel against degradation. This is because a fuels’ contact with water is one of its main causes for oxidation. Therefore, minimised contact with water is crucial.

    The unsaturation of oil occurs when there are one or more double bonds present in a fatty acid molecule chain. Saturated oil molecules are saturated with hydrogen atoms. Thus, unsaturated molecules are bonded to less hydrogen atoms and contain double bonds between carbon atoms. This affects the oxidation of Jatropha Oil because the lack of hydrogen atoms opens the molecule’s structure, making it susceptible to oxygen atoms. When oxygen atoms attach to the Jatropha Oil molecules, the oil starts to age or oxidize. The unsaturation of a fuel is represented with the iodine value. It is a measurement of the unsaturation of fats and oil and is expressed in terms of the number of milligrams of iodide absorbed per gram of a fuel (percent of iodide absorbed). The iodine value is closely linked to the acid value of a fuel. The acid value of a fuel is a measure of the amount of centigrams of sodium hydroxide, necessary to neutralise the free fatty acids (FFA) in one gram of fuel. Essentially, it represents the amount of free fatty acids in a fuel.