The Concept Of Deionized Water

Deionization of water is a process which removes all salts dissolved in water. This process involves passage of water through ion exchange materials to totally remove salt content. There are two ion exchange materials for this purpose.

Another term for deionization is demineralization, thus, demineralised water and deionized water are two similar terms, although the latter is more appropriate. The principle of ion exchange has long been used. Scientists knew about this for ages but only quite recently that this principle has been used extensively for practical purposes. This process has been highly reliable and greatly effective to treat water from minerals, which make water hard.
This process uses resin beads or granules, referred to as ion exchange material or bed, which contains insoluble anions neutralized electrically by sodium cations. This system softens hard water by stripping off calcium and magnesium ions in the water and replacing them with sodium ions.

During the first ion exchange calcium and magnesium ions are removed. This follows the water softening process. Industrial deionization removes positive metallic ions and replaces them with hydrogen ions. Home equipment does not achieve the same process because it releases sodium ions instead. The cations adhere to the ion exchange material. Metallic ions replace a number of hydrogen ions depending on the charge they are carrying. A sodium ion (Na+) replaces one hydrogen ion (H+). Two hydrogen ions are replaced by a calcium ion (Ca++) from the exchange material. An iron (III) ion (Fe+++) displaces three H+ ions. This way the ion exchange material maintains a balance of electrical charges in itself.

The introduction of hydrogen ions into the water results to a higher acidity. This is when the second step in deionization process steps in. The water contains hydrogen ions and remaining anions (negatively charged ions) after the first process.

The second process lets water pass through another unit where an anion exchange occurs. The ion exchange material this time takes negatively charged ions in the water, chloride ions (Cl-) for example, and replace them with hydroxyl ions (OH-). The resulting water contains H+ and OH- ions, which are actually ions composing water. Thus, the two processes mentioned actually demineralise water.

There different types of equipment used in the process. There is single deionization or multiple deionization bed units. The former mixes positive and negative ion exchangers in one tank, while the latter have separate tanks for cation exchangers and anion exchangers.

Industries have wide applications for demineralised water. Pharmaceuticals, leather goods processing, chemical production, and electroplating are some of the industrial applications of this kind of purified water.

An alternative for deionization would be distillation which is a more complex and more expensive process of water purification.

The safety of available water in the world is never guaranteed. This is why purification of water has always been a concern. A large percentage of water available for the public is often contaminated. This contamination comes from industrial and environmental waste. Pathogenic bacteria, heavy metals, and chemicals make water unsafe for human consumption. The health risks of contaminated water cannot be ignored. Reports have it that some liver problems and cancer can be linked to contaminants in water. Contaminants can be microorganisms like parasites and bacteria, or substances, which can be organic or inorganic. Organic substances come from different sources as decaying matter. Inorganic substances come from lots of sources from synthetic fertilizers in farms and infiltrate waterways to toxic lead present in PVC pipes.

There have been issues about drinking pure water because some experts believe that purified water without minerals is harmful to the body. According to them, pure water devoid of ions can cause loss of electrolytes in the body. But that is a simple explanation because their research indicate that loss of bone mineral and essential minerals in tissues can be a result of deionized water consumption. In addition, minerals present in water are beneficial to the human body, that there is no need to demineralise.

However, lots of scientists do not agree. Humans take minerals not from drinking water, which supply extremely minimal amounts of minerals, if anything; and that "minimal amount" is at the point of negligibility. Minerals used by human body come from food.

By: joalesto


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