Demineralization of Water Process

Demineralization of Water:

Ion-Exchange Process: Various synthetic ion-exchange resins are nowadays available for softening hard water. They are of two types:

Cation Exchange Resins represented by RH:

Hard water is first passed through cation exchange resins (RH) which removes all the cations like Ca⁺², Mg⁺², etc. An equivalent amount of H⁺ ions are released into water.

Anion Exchange Resins represented by NR₄OH:

The effluent water contains acids like HCL, H₂SO₄ etc. Hard water is then passed through a bed of anion exchange resins (NR₄OH) which removes all the anions like Cl^–, SO₄^2-, etc.

The removal of all the cations and anions of the dissolved electrolyte in water is known as Deionisation or Demineralization of Water.