Demineralization is the process of removing mineral salts from water by using ion exchange process. De-mineralized water is completely free (or almost) of dissolved minerals as a result of one of the following processes:
De-mineralized water also known as De-ionized water has its mineral ions removed. Mineral ions such as cat ions of Sodium, Calcium, Iron, Copper, etc. and anions such as Chloride, Sulphate, Nitrate, etc are commonly present in water. De-ionization is a physical process which uses specially manufactured ion exchange resins, which provides ion exchange site for the replacement of mineral salts in water forming H+ and OH- ions. Because the majority of water impurities are dissolved salts, deionization produces pure water that is similar to distilled water, and this process is quick and without scale build up. De- mineralization technology is a proven process for treatment of water. A DM water system produces mineral free water by operating on the principles of ion exchange, De- gasification and polishing. De- mineralized water system finds wide application in the field of steam, power, process and cooling.
PRINCIPLE : Raw water is passed via two small polystyrene bed filled with ion Exchange resins. While the cat ions get exchanged with hydrogen ions in first bed, the anions are exchanged with hydroxyl ions in the second one.
PROCESS : In the context of water purification, ion- exchange is a rapid and reversible process in which impure ions are taken up by the resin, and must be periodically regenerated to restore it to the original ionic form. (An ion is an atom or group of atoms with an electric charge. Positively charged ions are called cat ions and negatively charged are called anions, usually non metals).
DE IONIZATION : For many laboratories and industrial applications, high purity water, which is essentially free from ionic contaminants, is required. Water of this quality can be produced by deionization. The two most common types of deionization are Two- bed deionization & Mixed- bed deionization