Go Green :D: Extracting Limonene from Orange Peel

In Lesson 4, we extracted Limonene from Orange Peels using the following ingredients:

Distillation apparatus
Blender
Separating funnel
Stirring rod
3 x 100ml beaker
1 x 100ml conical flask
Hot plate

Scientific Concepts/ Processes behind the extraction of D-Limonene
As background knowledge, limonene is an essential oil with anti-carcinogenic properties and is used in numerous cleansing products. Limonene has a boiling point of 176 degree celsius, and appears as a colourless liquid at room temperature. In this experiment, we extract D-Limonene, which is an isomer of Limonene that smells like citrus.

Steam distillation is used to extract the d-limonene as it does not denature the structure of the essential oil molecules. The hot steam opens the pockets in which the oils are kept and releases the aromatic molecules from the orange peel. These essential oil molecules, which are volatile, then escape from the orange peel and vapourise before condensing and being collected.

This is something we should note: both the fruit flesh and fruit peel can be used as sources of fuel (limonene as biodiesel), however extracting limonene from the fruit peel would mean a higher yield of limonene. To further increase the yield of limonene, the orange peel's cellulose should be broken down into glucose to ferment and produce more limonene.

Why Limonene?
Limonene is a useful product which is extracted from fruit peels which would otherwise be discarded. Limonene is also combustible and hence can be used as a fuel. It can also be used in medicine and to promote weight loss, prevent cancer, treat cancer and treat bronchitis. In foods, beverages and chewing gum, it is also used as a flavouring. In pharmaceuticals, limonene is added to help medicinal ointments and creams penetrate the skin. In manufacturing, limonene is used as a fragrance, cleaner (solvent), and as an ingredient in water-free hand cleansers.

A more specific example to D-Limonene would be that of cancer treatment. D-Limonene seems to build up in cancer tumors, when it is taken by mouth in 21-day cycles. The high levels of limonene in the tumors may slow down the progress of the cancer, however, its effect on the person's survival is still uncertain.

Limonene is also safe in food amounts, and appears to be safe for most people in medicinal amounts when taken by mouth for up to one year.

As can be seen above, limonene is a very useful product in our lives.

Amount of Limonene extracted in our lab experiment
In our lab experiment, the results turned out quite positive:

Amount of orange peels used/g	Amount of D-limonene extracted/g	Percentage yield
54.06g	0.44g	0.814%

When we researched online, we found out that the expected percentage yield was about 1%. However, we suspect that due to that fact that not all of the blended orange peel could be added to the conical flask, there was a loss of mass even before steam distillation began. Hence, the size of the conical flask was a limitation for this experiment since we could not add more blended orange peel to the conical flask.

Pictures of Process and Final Product