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How is bromine released from bromides in seawater?
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halogen
Modern version of the periodic table of the elements.
Bromine is extracted from seawater through a process of chemical displacement, also known as oxidation.12
Because seawater contains a relatively low concentration of bromine—approximately 70 parts per million—large volumes of water must be processed to obtain the element. The extraction follows these steps:2
- Acidification and Oxidation: The seawater is first treated with sulfuric acid and then with chlorine. The chlorine acts as an oxidizing agent, displacing and releasing the bromine from the bromide ions present in the water.12
- Removal: A current of air is blown through the treated water to remove the free bromine, resulting in a dilute mixture of bromine and air.12
- Concentration: The bromine is absorbed into a solution, such as sodium carbonate, and subsequently treated again with sulfuric acid to release the bromine in a much more concentrated form.12
This process relies on the high reactivity of halogens, as their tendency to acquire electrons makes them strong oxidizers.34