De-ionizer (DI System)
A De-ionizer (DI system) is used to remove dissolved ions (salts) from water by ion exchange. It’s essential in chemical plants where ultra-pure water is required for boilers, lab use, pharmaceutical, electronics, and process systems. Unlike softeners, DI removes both cations and anions, making water highly pure (almost like distilled water).
Treatment Process
- Raw Water Inlet: Partially treated or RO water enters the DI unit.
- Cation Exchange: Cation resin removes positive ions (Ca²⁺, Mg²⁺, Na⁺) → replaced with H⁺.
- Anion Exchange: Anion resin removes negative ions (Cl⁻, SO₄²⁻, NO₃⁻) → replaced with OH⁻.
- H⁺ + OH⁻ = H₂O: The exchanged ions combine to form pure water.
- Mixed Bed (Optional): For polishing and highest purity, both cation + anion resins mixed together.
- Regeneration: When exhausted, resins are recharged using acid (for cation) and caustic (for anion).