Question

Cite two examples of where Ion Exchange is used in Industry (any method, anionic, cationic or

mixed bed), what is being removed, and why.

Answer 1

Ion exchange is used in a number of processes in various industries such as water treatment and purification, sugar industry, metal purification, pharmaceutical industry, food processing industries.
1) In water treatment, water softening is one of the most popular applications of ion exchange.

Water softening: Hard water is treated with the help of ion exchange. Hard water contains excess calcium and magnesium salts. These ions (calcium and magnesium) contribute to the hardness of the water which is highly undesirable. Therefore a strong acidic cation exchange resin comprising of sodium is used. These sodium ions at active sites is used to replace the calcium and magnesium ions in the hard water. As such, softening process of water is carried out. After softening the resin is regenerated by a solution rich in sodium ions such as sodium chloride.
In a nutshell, by using ion exchange method, the Calcium and Magnesium ions are removed from the the water in order to remove its hardness.

2) Ion exchange is used in a number of processes of sugar industry such as softening of sugar juices, softening of water for extraction purposes, Quentin process etc.
Quentin process : In sugar industry, the crystallization process forms the backbone of the product yield. The better the crystallization, better is the product quality and yield. The crystallization of beet sugar is hindered by the presence of potassium and sodium ions in the juice, as a result a considerable quantity of sugar remains in the molasses after crystallisation. Therefore an ion exchange process is done where potassium and sodium ions are replaced by magnesium ions. The juice is passed through a column of strongly acidic cation exchange resin in the magnesium form. Magnesium inhibits the crystallization process less as compared to sodium and potassium ions, hence increasing the production of white sugar and subsequently reduces the quantity of molasses produced.
So to sum it up, the sodium and potassium ions are removed in order to facilitate better yield of sugar.