Mercurius
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Safety Question - Ozonolysis Exhaust
Concentrated O3 is a powerful oxidant which causes severe respiratory distress and can harm lung and cardiopulmonary function. It is also quite
handy.
In order to operate a DIY ozone generator (75 kv/30 mA corona discharge) safely, I need your help to devise some measure for efficiently decomposing
O3 exhaust.
The general idea will be to bubble the O3 gas through a solution of some catalyst that will degrade the gas to O2. However, I am not sure what
reagents will accomplish this safely and efficiently. The solution should be reusable and readily decompose large volumes of concentrated O3/O2
exhaust gas.
Any ideas what might work?
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hissingnoise
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| Quote: | | Any ideas what might work? |
Because ozone is very unstable thermally, passing it through a heated tube should reduce it sufficiently.
Activated charcoal works too but the charcoal is slowly consumed and may be ignited by the reaction.
Catalytic destructors are expensive because they use precious metals. . .
http://www.ozoneservices.com/products/OLP/destructor.htm
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hissingnoise
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OTOH, you could just vent it outside - but ozone's toxicity is it seems to me, often exaggerated.
If you're using dry oxygen as feed gas the output could reach 15% O3 and this concentration *could* be considered dangerous.
Ozone can be noticed at PPM (some people can smell it at PPB?) and these concentrations are basically harmless.
If you're running the generator on air, NOx might be more problematic than O3.
BTW, ozone is fairly soluble in water, so feeding it into your attic water tank would dispose of it while sterilising your supply.
Then again the reaction you're using it for may consume the major proportion of O3.
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unionised
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Some people might prefer not to carry the unknown by-products of an ozonolysis reaction into their drinking water.
When I was using O3 I used silica gel coated with silver. It didn't take a lot of Ag to blacken the silica gel and a column with a few inches depth of
the stuff destroyed the O3 nicely. I'm not sure now how I coated the stuff. I think I shook the SiO2 with a solution of AgNO3 then dropped it into
alkaline vitamin C.
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hissingnoise
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| Quote: | | Some people might prefer not to carry the unknown by-products of an ozonolysis reaction into their drinking water. |
It wasn't a serious suggestion unionised; if I thought he was going to act on it I would have advised against. . .
For water treatment all ozone should be generated straight from O2!
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Panache
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I've always wanted to swim in an ozone treated pool, apparently its simply fresh water, like in the bath. The Aus swim team has ozone pools at their
high altitude training center at Mt Mount Kosciuszko (Australia's highest peak, lol, don't ask how high, ok all of 2200m roughly), and the general
public can go, but i can think of nothing worse that swimming around olympians, god waking up in the middle of the night is conducive to inane posts.
I use ozone to clean my doona/comforter/eiderdown as i have no garden and like that sun aired smell that UV gives, anyway on a serious note don't the
montreal protocol banned cfc's mop up ozone quite nicely, get on old fridge. Thats wasn't serious, i meant on topic.
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hissingnoise
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| Quote: | | I've always wanted to swim in an ozone treated pool. |
C'mon Panache, you know you'll miss the smell of chlorine and that dried skin feel. . .
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Formatik
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You could try sending the ozonized gas through a column packed with charcoal or graphite. These will decompose it to O2. The action is fairly rapid.
Ozone decomposition is exothermic, so more air dilution and a lesser flow rate would help in heat reduction.
This is why I never smelled ozone when I had an old gas mask on, even though I was in rooms saturated with the gas. It is for this reason gas masks
work well against ozone, since they have the carbon filters.
The Encyclopaedia Britannica mentions ozone is decomposed to an unlimited extent in contact with metallic silver, MnO2, PbO2, and CuO. The substances
are oxidized by the ozone and reduced by it also.
An idea on how to integrate those in a column besides using bulk powders (high surface area increases metal oxide catalytic activity towards the
ozone), is to drench a solution of the desired metal compound e.g. in diatomaceous earth or pumice, remove this from solution then react it with with
the solution that will get the desired catalyst i.e. oxide, dioxide. Then letting it dry. Either way, the catalyst material can be compacted in the
column with glass fibers.
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Sedit
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I played with tesla coils of various sizes for years and have become quite aquinted with the plesent smell of ozone. Im not dead yet after spending
hundreds of hours inhaling the O3 and nitric oxide fumes these things produce so I don't think you have much to worry about running an ozone generator
for a few hours. Why not just setup and leave with a good exaust fan running or something?
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Melgar
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The reactants should absorb virtually all of the ozone, until you've exhausted all your C=C double bonds, then the ozone will continue to oxidize your
reactants but not as readily. Thus, at this point, you will start to get ozone in the exhaust. One thing you can do is dissolve sodium or potassium
iodide in water, then mix in some corn starch. When ozone is present, the iodide will be oxidized to iodine, which turns black in the presence of
starch. This is a good indicator of when your reaction is complete, although it can turn black prematurely if you don't have thorough mixing of the
ozone rich air and your reactants. Iodide ions are really easily oxidized to iodine though, so you can always just use iodide solution as an
ozonolysis sponge.
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Formatik
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The serious damage from ozone inhalation in small amounts over a prolonged period probably will only show up in later years. I got lax with it while
doing an ozonation in the open garage, inhaled some and it then once caused a small amount of blood to appear from my throat (mild bloody sputum) for
several hours.
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Mercurius
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The feed gas is pure O2. And despite any advice to the contrary I can tell you that this gas is nothing to play with. The symptoms of overexposure
are very similar to an asthma attack, only more severe. After overexposure you will be bed-ridden for days in recovery. Corona discharge is
infinitely more efficient in generating ozone than.. say a jacob's ladder. Thanks for all the help and advice. Low levels of ozone are relatively
harmless, and an efficient bubbler setup should release a good portion of it into the solution, but my fear is that the connections feeding out of the
system will still immediately hold a high concentration of ozone, as the gas absorbtion will still be limited by the surface area of each bubble and
the duration each will spend in solution. A better indicator for this reaction can be incorporporated into the reaction itself, utilizing methanol as
the solvent, which forms a complex at extremely low temperatures that should appear a very distinctive tint of royal blue. I'm thinking that this
coated silica might just be the ticket, as ozone en mass and it's peroxide bridged byproducts have been known to deflagrate fairly readily under
certain conditions, and because the system is connected to an oxygen tank I am tempted to order at minimum a shatterproof blast shield. By and large,
the exothermic nature of this degradation process make me nervous. I have some unfortunate experience with this gas, more than enough experience to
know the dangers, but just how serious is the explosive hazard of organic peroxides at -70*C?
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peach
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In regards to breaking it down...
| Quote: | | Ozone is a pale blue gas, slightly soluble in water and much more soluble in inert non-polar solvents such as carbon tetrachloride or fluorocarbons
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Use a none polar in a wash flask with a frit?
Shine a none UV filtered mercury lamp at it?
Heat it up?
It also breaks down very rapidly in the present of Cl radicals. Whether you'd want them around in the first place is another thing.
| Quote: | | Ozone breaks down very rapidly in the wash liquor due to the pH and high alkalinity. By that time, it has already done its job. Once it comes out of
solution, it is merely air. Besides, your washers are designed to survive high caustic environments that are more corrosive than ozone.
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And from WikiAnswers...
| Quote: | Assuming the liquid is water...
Using intense 254nm UV will break ozone down without any chemical feed.
Ozone has a strong affinity for H2S, blue dyes, metals that are not fully oxidized, and any compound with carbon-carbon double bonds (aromatics).
Ozone survives just a few millimeters into either diatomaceous earth, multi-media sand, or granular carbon filters. Caution: ozone will convert
manganese to permanganate ion, which is water soluble and can be a whole different problem.
Heating the water and / or raising the water's pH above 8 will cause the ozone to decay more rapidly.
Waiting 24 hours will let the ozone decay without doing anything more.
Blowing air through the water will strip the ozone from the water, and place most of it in the air stream leaving the water.
Liquid ozone will spontaneously "deflagrate" to oxygen gas plus heat if you treat it less than gently. Think of a not very slow *boom*.
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SCREW THE FUME HOODS, BUY SOME FRITTED WASH FLASKS!
[Edited on 12-6-2010 by peach]
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Picric-A
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Try bubbling the O3 through a MnO2 suspension in KOH solution. You would be left with a load of nice KMnO4 crystals 
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