Ion exchange is the reversible interchange of ions between a solid and a liquid such as water. Ion exchange resins remove harmful contaminants from liquids, replacing them with beneficial, desired ions.
 

Ion exchange is used in water treatment, including water softening, industrial demineralization, condensate polishing, ultrapure water production, and wastewater treatment. It can also provide a method of separation in many nonwater processes, such as desiccation and chromatographic separation. It has special utility in chemical synthesis, manufacturing, food processing, mining,power industry, agriculture, and a variety of applications .