Which technology operates on the principle of exchanging ions to soften water?

Which technology operates on the principle of exchanging ions to soften water?

• A. Reverse osmosis
• B. Ion exchange
• C. Filtration
• D. Electrodialysis

Answer: (B)

Ion exchange softening works by swapping hardness-causing ions for sodium ions on a resin. Calcium and magnesium ions in the water are captured by the resin beads and released as sodium ions into the water, making it softer. When the resin becomes saturated with hardness ions, it’s regenerated with a salt solution to restore sodium on the beads and remove the accumulated calcium and magnesium. This direct ion-to-ion exchange on the resin is the defining principle of this softening method. Other methods operate by different means: reverse osmosis uses pressure to push water through a membrane, filtration removes particles by size, and electrodialysis uses an electric field to move ions across membranes rather than exchanging them on a resin.

Ion exchange softening works by swapping hardness-causing ions for sodium ions on a resin. Calcium and magnesium ions in the water are captured by the resin beads and released as sodium ions into the water, making it softer. When the resin becomes saturated with hardness ions, it’s regenerated with a salt solution to restore sodium on the beads and remove the accumulated calcium and magnesium. This direct ion-to-ion exchange on the resin is the defining principle of this softening method. Other methods operate by different means: reverse osmosis uses pressure to push water through a membrane, filtration removes particles by size, and electrodialysis uses an electric field to move ions across membranes rather than exchanging them on a resin.