Uses of Iodine

Uses
.

Iodine in Nature and its Isolation

The only stable isotope of iodine is I127, and is only present as iodide, I-. Only incredibly small amounts can be used before it becomes toxic. A table of it's abundance can be found under Basic Facts. Iodine doesn't usually need to be isolated since it can be purchased easily, but there are two ways to isolate iodine. The first involves seaweed, where iodide is turned into iodine through the following reaction:

2I- + Cl2 2Cl- + I2

The seaweed needs to be washed with chlorine, which releases the iodide as the gas, I2. Another way is more drawn out, but involves sodium iodide (solid) and sulfuric acid in the following reaction:

NaI(s) + H2SO4(l) HI(g) + NaHSO4(s)

This leaves hydrogen iodide, which can be reacted with more sulfuric acid to release I2, the gas:

2HI(g) + H2SO4(l) I2(g) + SO2(g) + 2H2O(l)

Iodine-131

Radioactive iodine is the most useful to humans. In 1942, Iodine-131 was discovered to be incredibly effective in treating hyperthyroidism. Hyperthyroidism is a disease where the thyroid produces too much of certain hormones (as shown in the picture to the right); these periods are called "thyroid storms" and can raise a sitting person's pulse to 120. The hormones are called T3 and T4, and when created in the right amounts, they regulate many aspects of our metabolism.

The main cause of hyperthyroidism is Graves' disease. Graves' disease's trademark is goiter, or an enlarged thyroid. Antibodies in the immune system attach to the thyroid, for unknown reasons, and make it produce more T3 and T4. Hyperthyroidism may also be caused by a single nodule in the thyroid going berserk and producing more of the hormone for no apparent reason. Taking medications with excess amounts of thyroid hormone in them can also bring it on.

What does this have to do with iodine? Radioactive iodine, especially iodine-131, is the most widely used treatment for hyperthyroidism. The iodine is poisonous when it enters the body and is absorbed by the thyroid nodules, thereby killing them. There are no other areas in the body where iodine is concentrated and used so there are very few side effects.

If you would like to know more about hyperthyroidism and treatment options, go to www.endocrineweb.com

Iodine in Daguerreotypy

Daguerreotypy is a very old form of photography that is now nearly extinct. It involves immersing a photograph in solutions of iodine ions and bromine ions. The first dip in the iodine gives that painting a straw color, the bromine deepens it to an orange-brown, and the second iodine dip produces a color close to purple. The picture on the right is an example of daguerreotypy.

If you would like to know more about daguerreotypy, go to

 www.daguerre.org 		http://www.daguerre.org/gallery/mhs/mhs_intro.html

Iodine in the Body

Iodine is the most essentiel element to humans. It is actually taken in as the I- ion, iodide, since iodine itself is toxic. Thyroxin, the hormone produced by the thyroid, is 65% iodine. The thyroid is responsible for metabolism and the regulation of the the body's growth in general. Everything from bone growth to reproduction are managed at some level through the thyroid. This is why it is so important to have healthy iodine levels in your body. Many developing nations do not have the iodized salt that we do to aid in preventing iodine deficiency.

To learn more about the situation there, go to

www.dhhs.tas.gov.au/publichealth/foodandnutrition/iodine/pdfs/peh_iodine1_tasdeficiency1001

Iodine is especially important to woman because it has been shown to have a role in preventing breast, ovary, and uterine cancer.
  • Potassium iodide can also be used for skin problems such as acne.
  • Iodine tincture is used as an antiseptic to help kill bacteria.
  • Silver iodide used to be used to spray in clouds and help bring rain, but that wasn't very good for the environment, so they stopped.

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