Deionized water is one of the purest forms of water and is suitable for use in a variety of industries including medical, laboratory, and food processing. In this article, we will look at how deionized water works, how it differs from other types of water filtration, and whether drinking deionized water is good for your health. Finally, we will show a deionized water machine suitable for use in a laboratory.

What is water deionization?

Water deionization is the removal of ions, such as minerals and salts, from water through an ion exchange process. Ions are electrically charged atoms or molecules that have a net negative or net positive charge. In the deionization process, water flows through a layer of positively or negatively charged resin beads. The positively charged resin attracts and traps negative ions, while the negatively charged resin attracts and traps positive cations. The resin then releases hydrogen ions (H+) in exchange for cations and hydroxide ions (OH-) in exchange for anions. Finally, the hydrogen and hydroxide ions combine to form water (H+ + OH- = HOH or H2O). Only water molecules remain, which is why deionized water is known as one of the purest forms of water.

What does deionization remove from water?

Deionization removes ions from water, including the following dissolved salts and minerals.
Calcium
Iron
Sodium
Magnesium
Chlorides
Nitrates
Sulfate
Carbonate
Silicon Dioxide
Iodine

How is deionized water made?

The process of preparing deionized water involves several steps designed to remove harmful ions from the water supply. The most common method is ion exchange, which involves the use of specialized resins to capture and exchange ions in the water.

1. Pre-treatment
Prior to deionization, the water needs to be pre-treated to remove large particles, sediments and organic contaminants. This is usually accomplished through filters, carbon blocks, or reverse osmosis membranes. Pretreatment helps to extend the life of the ion exchange resin and improve efficiency.

2. Ion Exchange Process
This is where the true deionization process takes place. The water passes through a group of ion exchange resins to form pure water.

3. Mixed Bed Deionization
To obtain extremely pure water, a mixed-bed resin system can be used. This system contains both cationic and anionic resins in a single unit, allowing for finer removal of ionic impurities. This system is commonly used in laboratories and industries that require ultra-pure water.

How to measure deionized water?

The quality of deionized water depends on its conductivity and resistivity. Deionized water (DI) contains almost no ions and therefore has low conductivity and high resistivity. The lower the conductivity and the higher the resistivity, the higher the quality of the deionized water.

Why is deionized water important?

Deionized water is very important in the laboratory and medical industry. Deionized water is an essential part of providing safe and reliable medication and care. The purity and reliability of deionized water also prevents unwanted reactions and ensures the accuracy of laboratory tests and experiments.

Can I drink deionized water?

Yes, you can drink deionized water, but it’s not always the best option. Remember, deionized water only removes ions, so if you’re going to drink deionized water, make sure the water has also been treated to remove bacteria, viruses, and other harmful contaminants. Deionized water does not contain any minerals or electrolytes, so it may taste bland and not quench your thirst.

Three Types of Deionization

Depending on the type of resin used in the ion exchange process, there are three types of deionization: weak base deionization, strong base deionization, and mixed bed deionization.

1. Weak base deionization
Weak base deionization uses a resin consisting of a strong acid cation and a weak base anion. It is specifically designed to remove minerals from water and reduce hardness. Weak-base deionization produces the lowest quality deionized water compared to strong-base deionization and mixed-bed deionization, but is commonly used for stain-free car washing and window cleaning.

2. Strong-base deionization
The strong base deionization method uses a resin consisting mainly of strong base anions and strong acid cations to produce deionized water of medium quality. Similar to weak-base deionization, strong-base deionization removes minerals and alkalinity from water, and is also effective in removing silica. Strong base deionization is commonly used in the manufacturing industry because it is less acidic and gentler on metals.

3. Mixed Bed Deionization
Mixed bed deionization technology uses a resin consisting of a 40:60 ratio of strong acid cations and strong base anions to produce the purest deionized water. It essentially combines the advantages of weak base deionization and strong base deionization to effectively remove all ions from water. Mixed bed deionization technology is used in a wide range of applications including medical, pharmaceutical, laboratory testing and electronics.

Deionized water vs distilled water

Deionized water and distilled water are similar in that they both produce highly pure water, but they use two different processes. Deionized water removes ions from the water through an ion exchange process, while distillation simulates the hydrological cycle. While distillation is very effective at removing minerals and salts, and can even remove some substances that deionization cannot, distilled water is not the same as deionized water. Instead of passing through steam, deionized water exchanges water with hydroxide and hydrogen ions through a resin bed. A distiller, on the other hand, converts the water to steam, removing a variety of contaminants that do not evaporate with the water. When the water returns to its liquid state, it is free of any contaminants.