Explain with an equation how the method of ion exchange works for water treatment.
The method of ion exchange is used for water treatment to remove certain ions from water and replace them with other ions. It involves the use of an ion exchange resin. Here’s how it works:
Na+ (resin) + Ca2+ (water) → Ca2+ (resin) + 2Na+ (water)
In this example, the ion exchange resin initially contains sodium ions (Na+). As water containing calcium ions (Ca2+) passes through the resin bed, the sodium ions are exchanged for the calcium ions. The resin captures the calcium ions and releases sodium ions into the water, resulting in softened water with reduced calcium content.
The process can be regenerated by rinsing the resin with a concentrated salt solution, such as brine (sodium chloride). This displaces the calcium ions from the resin, and they are washed away, allowing the resin to be reused for subsequent ion exchange cycles.