What does deionize mean?
To deionize is to remove dissolved ions — charged particles such as sodium, calcium, chloride, and sulfate — from a liquid, most commonly water. The process typically involves passing the liquid through ion-exchange resins that swap hydrogen and hydroxide ions for the unwanted mineral ions, yielding extremely pure water. Deionization is essential wherever even trace minerals would cause problems: in laboratories preparing chemical solutions, in pharmaceutical manufacturing, in semiconductor fabrication, and in industrial boilers and cooling systems where mineral deposits cause scaling and corrosion. The word is technical rather than conversational, appearing chiefly in scientific, engineering, and commercial contexts, often in the adjective form "deionized," as in deionized water. It derives from the prefix de- (removal), combined with ion, which comes from the Greek ion, meaning "going," because ions migrate toward electrodes.
verbTo remove dissolved ions (such as salts and minerals) from a substance, especially water, typically by passing it through ion-exchange resins.
- To remove dissolved ionic impurities from a liquid, especially water, using ion-exchange or similar purification methods.
"The laboratory deionizes all water used in reagent preparation to ensure accurate results."
"The lab deionizes all water before it is used to prepare chemical reagents."
"Because the cooling system's components corrode easily, the plant deionizes the feedwater continuously."
Deionized water is so hungry for ions that drinking it in large amounts can actually leach minerals from your body — chemists use it precisely because it's a solvent that takes nothing for granted.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of deionize
"Deionize" is formed from the prefix de-, indicating removal or reversal, plus "ionize," which combines "ion" with the verb-forming suffix -ize. The noun "ion" was coined in the nineteenth century by Michael Faraday and William Whewell from the Greek ion, meaning "that which goes," the neuter present participle of ienai, "to go," chosen because ions travel toward electrodes during electrolysis. The verb is standardly spelled "deionize" in American English and may appear as "deionise" in British English.
Related word forms
How deionize is actually used
"Deionize" is a technical term used mainly in chemistry, engineering, laboratory work, and industrial contexts; in everyday speech people more often refer simply to "purified" or "filtered" water. The British spelling "deionise" is an accepted variant.
Easily confused with deionize
Ionize means to add ions or convert into ions, whereas deionize means to strip ions out of a substance such as water.