Previously, high purity water was used only in limited applications. Today, deionized (Dl) water has become an essential ingredient in hundreds of applications including: medical, laboratory, pharmaceutical, cosmetics, electronics manufacturing, food processing, plating and countless industrial processes (even the final rinse at the local car wash).

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Deionized water (DI water or de-ionized water; also spelled deionised water) is water that has had its minerals removed, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. Deionization is a physical process which uses specially-manufactured ion exchange resins which bind to and filter out the mineral salts from water. Because the majority of water impurities are dissolved salts, deionization produces a high purity water that’s generally similar to distilled water, and does so quickly and without scale buildup. However, deionization does not significantly remove uncharged organic molecules, viruses or bacteria, except through “accidental” trapping by the resin. Specially made strong base anion resins can remove

Gram-negative bacteria.

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The Deionization Process

The vast majority of dissolved impurities in modern water supplies are ions such as calcium, sodium, chlorides, etc. The deionization process removes ions from water via ion exchange. Positively charged ions (cations) and negatively charged ions (anions) are exchanged for hydrogen (H+) and hydroxyl (OH-) ions, respectively, due to the resin’s greater affinity for other ions. The ion exchange process occurs on the binding sites of the resin beads.

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Deionizer Types

For discussion purposes, affordable deionizers exist in two basic forms: disposable cartridges and portable exchange tanks. General Water Technologies does not use disposable cartridges. We utilize portable exchange tanks of mixed-bed deionizers which have both cation resins and anion resins provided in the same vessel. The highest quality water is produced by

mixed-bed deionizers.