About two decades ago, the use of highly purified water was only limited to a few commercial and industrial applications. Two common forms of purified water are used today, distilled water and deionized (DI) water. Although water purification can be done through other processes, including carbon filtration, reverse osmosis, microporous filtration, ultraviolet oxidation, ultrafiltration and electrodialysis. This high purity water product is now considered a very important ingredient in many pharmaceutical, medical, laboratory, manufacturing, food processing and a wide variety of industrial processes, as well as for rinsing the vehicle at the car wash local.
In recent years, a combination of the above processes has been implemented to produce water with very high purity, whereby its trace contaminants are measured in parts per billion (ppb) or parts per trillion (ppt). Deionized water is currently used in most science, technology, and engineering industries and is manufactured in a variety of purity levels. This type of purified water undergoes a process in which its mineral ions, such as calcium cations, sodium, iron, copper, and anions such as chloride and bromide, are removed. The deionization process employs the use of specially produced ion exchange resins, and these work to filter and bind mineral salts from the water. Since a large portion of the impurities in water consist of dissolved salts, deionization creates a higher level of purity that is commonly similar to distilled water. However, the deionization process does not remove most uncharged organic molecules, viruses, or bacteria, except with the use of specially formulated strong-base anion resins that can eradicate gram-negative bacteria. This chemical process can be carried out continuously and is quite cheap, through the electrodeionization method.
The Deionization Process: To create deionized water, scientists and chemists remove ions from the water using an ion exchange method. In return, positively charged ions and negatively charged ions are exchanged for hydrogen (H+) and hydroxyl (OH-) ions, due to the higher affinity of the resin for other ions. The ion exchange process takes place at the binding sites of the resin beads. Once the ions have exhausted their exchange capacity, the resin bed is refreshed or reinvigorated with concentrated and caustic acid, reducing or removing the accumulated ions through physical displacement, leaving only hydrogen or hydroxyl ions in their place. For most laymen, it should be remembered that the deionization process does not remove hydroxide or hydronium ions from water because water is known to self-ionize to reach equilibrium, which would lead to the removal of water itself.
Aside from its importance as a laboratory reagent and ingredient, deionized or distilled water is also commonly used to recharge lead-acid batteries used in most trucks, buses, and automobiles. This is the case, because if vehicles only use pure tap water, the presence of foreign ions usually found here is known to cause a significant reduction in the projected life of a car battery. All of this helps explain why deionized water is the fluid of choice for use in most automotive cooling systems today. Due to the high levels of minerals and ions found in tap water, it can lead to rapid corrosion of internal vehicle engine components and can also cause a more rapid depletion of anti-corrosion additives, which are present in the most antifreeze formulations. . Deionized water is also a very important component in major automotive cooling systems, where distilled water is interleaved or mixed with the hybrid system coolant to prevent further component corrosion.