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I produce ozone gas with an ozone generator based on corona discharge principle. These kind of ozone generators have the disadvantage that if $\ce{N2}$ is present, a bit of $\ce{NO}$ and $\ce{NO2}$ will be produced too. To produce oxygen I use a oxygen concentrator, with an output of about $90\%$ $\ce{O2}$ and about $10\%$ $\ce{N2}$. For that reason I have a little quantity of $\ce{N2}$ entering the ozone generator, which subsequently lead to unwanted side reactions like $$\ce{N2 -> NO -> NO2}.$$

The $\ce{NO2}$, even in that small quantity as it is, does influence the following processes in an negative way.

The easiest way to circumnavigate this issue would be to take pure oxygen – however for cost reasons I cant use LOX, so I have to stay with the concentrator.
I am searching for an reagent or an catalyst, which is not effected by the ozone but does absorb or disintegrate the $\ce{NO}$, and especially the $\ce{NO2}$.

To stripe $\ce{NO2}$ from a normal gas is not so difficult, but the ozone does make trouble. I thought about dry $\ce{NaOH}$, soda lime, or dry $\ce{KOH}$, but I have the feeling that these chemicals will react with $\ce{O3}$.

Any suggestions?

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  • $\begingroup$ I have a feeling they won't. $\endgroup$ – Ivan Neretin Jan 19 '18 at 4:54
  • $\begingroup$ Well it is difficult to find information about it. I have found that KOH will react with O3 to KO3 at room temperature. Don't know about NaOH - I guess I will have to try it. $\endgroup$ – Andreas Jan 19 '18 at 10:15
  • $\begingroup$ @Andreas why don't you make the experiment by yourself to find how much of them react or not and then show us what you found? :-) $\endgroup$ – ParaH2 Jan 21 '18 at 16:08
  • $\begingroup$ that is exactly my plan for next weekend ;-) $\endgroup$ – Andreas Jan 21 '18 at 19:42
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There is no need to use caustic since $\ce{NO2}$ reacts with water itself. As per [1] it is even better absorbed in water than in $\ce{NaOH}$.

Ozone is soluble in water depending on the concentration of $\ce{O3}$ in the gas phase. It is much more soluble than oxygen so you will loose some, but it will have much lower concentration of $\ce{NO2}$. Of course, the washed ozone will be moist. If you need it dry, you can use a column of molecular sieves or some other desiccant.

[1] Absorption of Nitrogen Dioxide by Aqueous Solutions, F. S. Chambers Jr., T. K. Sherwood, Ind. Eng. Chem., 1937, 29 (12), pp 1415–1422

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