The use of ion exchange to remove ionic substances from a solution(noun)
The return of an ionized gas to its neutral state(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "deionization" in a sentence
"This is due to the deionization of the plasma of material at the end of the radiation dominiated period."
"Maybe we are getting signals from the decoupling of gravity & gauge fields analogous to the deionization phase of the universe about 380,000 years after the big bang."
"And the deionization of Tom DeLay has been a great sport in Washington, not so much here in New York, but in Washington."