Deionization of water – An Overview

What is Deionization or Demineralization Process?
Deionization process is the removal of salt that are dissolved in water. For the process, water is passed through ion exchange material that remove the salt completely. Ion exchange is the reversible exchange of ions between solid and liquid without any change in the solid structure. Calcium bicarbonate, magnesium sulfate, and sodium chloride are the main salts present in the water that are removed by this process.

Deionization is also known as demineralization thus if you talk about demineralised or deionized water it is one and the same thing. Removal of salt especially from bones is also called demineralization. But of we talk about water then this process is also called desalinization. Sea water is converted to fresh water with this process which then can be used for irrigation, drinking and other such purposes.

Ion exchange resins are kept in pressure tank. The water that is to be deionized is then forced through the resins in deionizers. Resins get exhausted after a said amount of time and amount of water, so they no longer exchange the additional ions. For the regeneration of resins these will have to be regenerated with strong acid and base. Hydrochloric or sulphuric acid is generally used to restore the cation resin and sodium hydroxide is used for the regeneration of anion resin.

Deionization Advantages
The water produced by the process of deionization process if far superior quality than produced through distillation.

Deionizers or demineralizers come in variety of sizes like from the laboratory equipments to the one which are accommodating about thousands of liters per minute.

It is used for high-pressure boiler feed water.

No chemical or dangerous waste is produced in the process.

Through this technology heavy metals are removed from the water.

Deionization Disadvantages
Efficiency of the deionization process increases by using mineral water. So you have to use mineral water in this case which is the biggest disadvantage.

If possible remove iron and chlorine before deionization process. These are degrading agents and resin foulants.

Demineralization of water cannot remove certain forms of silica such as colloidal or non-reactive.