# What will happen if I trap an ozone producing device inside a small airtight area? [closed]

I'm currently building a UVC light, and right now I'm working on figuring out how to place it in an aluminum reflector housing to cast the beam of light effectively. It's creating a lot of ozone, and I'm worried about the longevity of the aluminum reflector it's going to be placed inside, as I know ozone oxidizes and corrodes metals. If I make this airtight with a lens on the front, will the ozone production cease after the oxygen inside converts? Will any dangerous conditions occur inside if it's not ventilated? Will ventilation create more ozone to the structure, or less?

I don't think you will have any problems with your aluminium because most of the aluminium usually is already passivated by a layer of aluminium oxide ($$\ce{Al2O3}$$), this depends actually on the alloy that you are using but if you buy normal aluminium most of the time has this behaviour. If the enclosure it's watertight all the oxygen will be converted in ozone, and when the oxygen will run out the reaction will stop, if the enclosure has some leakages you will continue to create ozone so you will have to operate the lamp in a ventilated environment.

If the environment is watertight and the UV lamp is generating a lot of heat you could have a substantial increase in pressure. This could cause your window to break or explode.

One problem I see (other than creating a very toxic high concentration of ozone) is the ozone itself quickly reacts with organics, including lubricants, tubing,.. used in the machine producing it. Per a source, to quote:

Ozone is an effective sterilant due to its ability to oxidise most organic matter...

During ozone sterilisation, ozone breaks down into reactive species, including hydroxyl radicals and atomic oxygen. Because of the strong oxidising nature of ozone, polymers must be resistant to oxidation. Polymers and medical devices should also be resistant to high relative humidity levels (> 80%), which are required for ozone to be effective. Consequently, materials should be resistant to oxidation and moisture.

As such, in the presence of significant water vapor, a possible corrosion problem with ozone attacking the OH- ion (formed in the dissociation of water), to quote a reference:

The first reaction that takes place is accelerated ozone decomposition by a type of initiator. This can be an OH-molecule, see reaction 1:

1: $$\ce{O3 + OH- -> •O2- + HO2• }$$

This radical has an acid/ base equilibrium of pKa = 4,8. Above this value, this radical no longer splits, because it forms a superoxide radical, see reaction 2:

2: $$\ce{HO2• -> •O2- + H+ (pKa = 4,8) }$$

3: $$\ce{O3 + •O2- -> •O3- + O2 }$$

4: $$\ce{•O3- + H+ -> HO3• (PH < ≈ 8) }$$

The OH-radicals that have formed react with ozone according to the following reaction mechanism:

5: $$\ce{OH• + O3 -> HO4• }$$

6: $$\ce{HO4• -> O2 + HO2• }$$

During the last reaction, HO2• radicals are formed, which can start the reaction all over again (see reaction 2). As a result, a chain-reaction develops, which is maintained by so-called promoters.

The latter HO2• is highly acidic (see ‘Radical-Enhanced Acidity: Why Bicarbonate, Carboxyl, Hydroperoxyl, and Related Radicals Are So Acidic’) and could attack metal, like Aluminum forming Al(OH)3 or hydrated Al2O3.

Bottom line, I suspect, in time this will prove to be a bad idea, and could result in significant harm to the machine, and any leakage of ozone is problematic, given its potential health issues, to quote a government source:

When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections.

• And a UV (ozone) cleaner is a nice (and pretty standard) lab device to get residual organic crud off of surfaces you want to be clean... Apr 9 '20 at 18:45