How is iodine extracted from iodine-containing brines?

Iodine is commercially extracted from brines through a multi-step process designed to isolate and purify the element.1

First, impurities such as clay, sand, and oil are removed from the natural brine via filtration. The clarified solution is then passed through a stream of sulfur dioxide and subsequently through containers holding bundles of copper wire. This process causes the formation of copper iodide, which is collected by filtration, washed, dried, and finely ground.1

To obtain the free element, the copper iodide is heated with potassium carbonate to produce potassium iodide. This compound is then oxidized to release free iodine using sulfuric acid and dichromate. Alternatively, chlorine may be used as the oxidizing agent in this process.1