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Ion exchange: What is it and how does it work?

Article | 23 October 2024
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Ion exchange: What is it and how does it work?

In ion exchange, unwanted ions (charged particles) in water are replaced or removed by a special material, such as a resin. This is done by adsorption, where the ions bind to the solid material. For example, in water softening, calcium ions (which cause hard water) are exchanged for sodium ions. In other cases, such as in the production of demineralised water, the ions are removed from the water altogether without a replacement ion replacing them.

There are many different types of resins available, each with their own properties. When an ion exchanger becomes full of the unwanted ions, it is cleaned with a regeneration agent.

There are two main types of ion exchangers: cation exchangers, which bind positive ions, and anion exchangers, which bind negative ions. Sometimes systems containing both types of resin are used (mixed bed systems) for more effective treatment.

Ion exchangers in practice

In practice, ion exchangers are often placed in special chambers (filter tanks) filled with granular resin. These chambers have screens at the top and bottom to prevent the resin from washing away. Depending on the application, the ion exchanger can consist of one type of resin (for cations or anions only) or a combination of both (mixed bed).

The tanks can be made of different materials, such as plastic or steel, depending on the capacity needed. Plastic is usually used for smaller flows, while steel is more often used for larger water flows.

There is a large range of resins available, each suitable for specific applications.
Wondering what other water treatments there are? Check out our knowledge base!

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