Deionizers remove the ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure. They are used to purify water and are an important part of aquariums and laboratory environments that are used to maintain marine life. Deionizers are also used to purify water for use in biology and chemistry laboratories.
Deionizers consist of one or more deionization cartridges that are connected to a water supply. Deionization is the process of exchanging the contaminant cations with hydrogen and contaminant anions with hydroxyl ions, respectively. Deionizer cartridges contain a specific resin of tiny beads. When the water passes through the resin, the impurities are replaced by free hydrogen and hydroxyl groups. Replacement of the resin is required when all of the hydrogen and hydroxyl groups have been replaced by contaminant cations and anions. Deionized, mineral-free water is used in many industries, especially in chemical and pharmaceutical production and electroplating applications.
Many types of deionizers are available. Some deionizers have only one bed. Others products use multiple bed systems. In a one bed system, the ion removal or demineralization takes place in one tank or exchanger. In a multiple bed system, the ion removal process is separated into different tanks, with the cation exchange taking place in one bed or cartridge, and the anion exchange taking place in another.
Deionizers may incorporate technologies such as carbon filtration, ultraviolet (UV) sterilization, and reverse osmosis systems. Deionization systems vary in size and the frequency with which the resins must be regenerated. When the resins are saturated with contaminant ions, they are washed with different solutions. The cation resin is washed with a diluted hydrochloric acid solution, while the anion resin is washed with a diluted sodium hydroxide solution. The tanks are washed thoroughly to remove any chemical residue before being returned to service.