What are the processes for producing deionized water?
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Update time : 2025-08-07 18:05:37
What is deionized water? Deionized water is water that has had its ions and solutes removed, resulting in a near-zero electrical conductivity. It is used in the pharmaceutical, electronics, and semiconductor industries. Deionized water has a high purity, an extremely low inorganic ion content, and extremely strong solvent capacity, making it an ideal high-purity solvent.
Deionized Water Production
The production of deionized water requires specific process steps. The main principles are electrolysis, reverse osmosis, and mixed-bed processes. We will explain each of these below.
Electrolysis
The electrolysis process uses charged positive and negative electrodes in an electrolytic cell to electrolyze water, separating the ions using membrane separation technology to achieve deionization. During this process, water molecules are broken down into H+ and OH- ions, which are finely separated and transferred to a diode. Ions are removed from the water, resulting in deionized water.
Reverse Osmosis
Reverse osmosis utilizes membrane separation technology to allow a high-concentration solution to naturally permeate through the micropores of a reverse osmosis membrane into a low-concentration solution, forming a high-concentration solution within the membrane. This method primarily utilizes polymer membrane filtration to remove produced water. This method is simple to operate and offers high throughput, but requires a high-pressure pump and can be difficult to completely remove some oligomers and organic matter.
Mixed Bed Method
The mixed bed method is a common and widely used deionized water production process. It combines cation exchange resin and anion exchange resin in an expanded exchange bed, producing water through sequential elution and regeneration. This method requires repeated treatment, and long-term use requires maintenance and replacement. The mixed bed method achieves water quality as high as a theoretical value of 18.25 MΩcm.
