# How to measure ozone output of an ozone generator using chemical methods

I have the need to optimize an corona discharge based ozone generator. There are certain variables like frequency and voltage which I can change.

The easiest way would be to use an ozone analyzer – however these things are quite expensive and over my budget currently.

I have tried certain ways to get a hold on numbers but failed so far.

Example: I used activated charcoal to convert the $\ce{O3}$ to $\ce{CO2}$ and tried to measure the $\ce{CO2}$ ppm, however it turned out that the activated charcoal did absorb the $\ce{CO2}$, so this measurement did not work..

Is there a easy to do chemical way to react the $\ce{O3}$ with something, that can be measured/done by a hobby chemist? My aim is to find at least a setup with the maximum ozone output. If it is possible to calculate how much grams ozone were produced it would be even better.

• For optimization purposes, perhaps something as simple as a solution of KI with added starch (e.g., laundry spray starch). More ozone means more intense blue color from the starch-iodine complex. And a blank is easy. – Ed V Aug 7 '19 at 13:33
• Back titrate the iodine with standardized thiosulfate solution. – user55119 Aug 7 '19 at 14:16

You can do the quantitative estimation of ozone ($\ce{O_3}$) by two reactions. First one is the reaction between $\ce{O_3}$ and potassium iodide ($\ce{KI}$), and the second one is an iodometric titration.

First, ozone is reacted with excess $\ce{KI}$ in presence of borate buffer ($\mathrm{pH} =9.2$), and due to this reaction, iodine ($\ce{I_2}$) and oxygen ($\ce{O_2}$) are liberated as follows, $$\ce{O_3 + 2KI + H_2O -> I_2(^) + O_2(^) + 2KOH}$$

Now this mixture of gases is passed through potassium pyrogallete solution, which absorbs $\ce{O_2}$, and we are left with $\ce{I_2}$. Next, this liberated iodine is dissolved in a solution to make a particular volume, and then titrated with sodium thiosulfate ($\ce{Na_2S_2O_3)}$ of known strength in the presence of starch indicator.

$$\ce{I_2 +_ 2Na_2S_2O_3 -> Na_2S_4O_6 (sodium tetrathionate) + 2NaI}$$

At the end point of this titration, colour of the solution turns colourless from blue ($\ce{I_2}$ + starch gives blue colour complex which is lost at the end of this reaction).

So, thiosulfate reacts with iodine in a quantitative manner, and from there you can determine equivalents of $\ce{I_2}$ = equivalents of $\ce{Na_2S_2O_3}$. Thus, you can calculate what equivalents of ozone had produced that much of $\ce{I_2}$, and also the grams of ozone present.

• seems like if you have a pH meter you could just monitor pH of the borate buffered solution (KOH is formed). How critical is the pH? Maybe you could also use unbuffered calcium iodide and just measure the precipitate as $\ce{Ca(OH)2}$ is formed. – Curt F. Apr 9 '19 at 16:47

Any redox reaction should do for this. Since ozone is a powerful oxidizer. I would have to agree with Soumik Das on his method. It would be the easiest. Most of those chemicals (assuming you don’t have access to a lab like me) are easily purchased.