The production of demineralised water using ion exchange resins is a highly effective and well-established method for the complete removal of dissolved salts. This process is particularly widely used in the energy, pharmaceutical, chemical, electronics and food industries, where ultrapure water is essential for the proper functioning of plant equipment and the quality of the final products.
The Demineralisation Process Using Selective Resins
The ion exchange system is based on the use of cationic and anionic resins, which selectively remove ions from the water:
- Cation Exchange
Cationic resins in the H⁺ form replace positive ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, Fe²⁺) with hydrogen ions (H⁺). - Anion Exchange
Anion exchange resins in the OH⁻ form remove negative ions (Cl⁻, SO₄²⁻, NO₃⁻, CO₃²⁻) by replacing them with hydroxide ions (OH⁻). - Production of Demineralised Water
When H⁺ and OH⁻ ions combine, they form H₂O, leaving the water with an extremely low conductivity (<1 µS/cm)
Regeneration of Resins
When resins become saturated, they must be regenerated to restore their ion-exchange capacity:
- Cationic resins are regenerated using sulphuric acid (H₂SO₄) or hydrochloric acid (HCl).
- Anionic resins are regenerated using caustic soda (NaOH).
Advantages of Demineralisation Using Selective Resins
- High-purity water with very low conductivity.
- A continuous and reliable process, ideal for critical industrial applications.
- Effective removal of all dissolved salts, including silicates and complex anions.
- Option to customise the system with mixed-bed resins for even higher quality.
Applications
- Thermal power stations (boiler and turbine feed).
- Pharmaceutical and cosmetics industry (production of ultrapure water).
- Food industry (treatment of process and dilution water).
- Electronics sector (precision cleaning using contaminant-free water)
The use of selective resins for demineralisation offers a flexible, efficient and sustainable solution, ensuring high water quality and low operating costs.
