Ion Exchange

Definition

The process by which a softener resin swaps dissolved hardness ions for sodium ions held on charged resin beads. It removes calcium and magnesium before water reaches the boiler.

Inside the softener tank thousands of resin beads carry a fixed negative charge and are coated with weakly held sodium ions. When hard water flows through, the doubly charged calcium and magnesium are more strongly attracted and displace the sodium, leaving the water with sodium in place of hardness and zero scaling potential. The exchange is reversed during regeneration with concentrated brine.

Related concepts

Hardness · Brine Tank · Regeneration

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Part of The Blueprint of Water · 🧪 chemistry