Answer to Question #233512 in Chemical Engineering for Lokika

Question

What are the principles of an lon-exchange?

Answer 1

Ion exchange is the process through which ions in a solution are transformed into a solid which release ions of a different type but of the same polarity. This means that the ions in solutions are replaced by different ions originally present in the solid.

Ion exchange is a very powerful method to remove impurities, residues and contaminants from water.

For the ion exchange, substances are used that have a surface property allowing ions to adhere very well (= so-called ion exchangers). These ion exchangers are loaded with positively charged hydrogen ions H+ and/or negatively charged hydroxide ions OH-.

These ions have a low charge (+) (-).

The higher the charge and the smaller the radius of an ion, the more the ion is bound to the ion exchanger.

If the water to be treated is now passed through an ion exchanger with positive and negatively charged ions, all positively charged cations (+) in the water are replaced with positively charged hydrogen ions (H⁺) and all negatively charged anions (-) in the water are replaced with negatively charged OH ions (OH^-). This means that the ion exchanger repels all hydrogen and hydroxide ions and picks up the positive and negative ions from the water. The H+ and OH^- ions repelled by the ion exchanger now combine to ultrapure, residue-free water outside of the ion exchanger.

This process takes place until the ion exchanger no longer can give off any H+ or OH- Ions.