Sciencemadness Discussion Board

Ozone generator.

Tacho - 30-3-2004 at 00:31

Some time ago, I have built an ozone generator capable of filling the ambient with that smell. I would guess I had a 0,5% ozone coming out of the “corona chamber”. The best part was to watch the corona inside (I had a window). Some beautiful visual happened there.

The main problem was overheating of the transistors. The apparatus could only work for a few minutes. I used the classic 2 transistor (2N3055) circuit. I used huge dissipators.

Recently there was some discussion on the V2O5 thread about ozone generators. I began to have that “Close-encounter –of-the-third-kind-fixed-idea”. You remember the 77’s movie: Richard Dreyfus gets fixed on sculptures of the mountain (potato puree and so on). This happens to me with my projects. BTW does this happen to anyone else or should I look for medical help?

So I took a look at my old fellow countryman Sam Barros' page and gess what I found:

http://www.powerlabs.org/flybackdriver.htm

A one transistor driver! I thought: that’s soooo easy to make...

So I made it in 10 minutes and, to my surprise, works very well, with no overheating. This thing can run for hours! I used a rectified 12V transformer, so I estimate the voltage applied in about 17V.

So now I’m planning to do some research on the best cheap corona discharge chamber.

Out of SHEER ENVY I might try to mix ozone and SO2 from a sulfur candle and post the results before axehandle!

I attach a picture of the flyback circuit.

flyback.jpg - 13kB

axehandle - 30-3-2004 at 05:17

That's very nice of you. I already built an ozone generator though, out of a drinking glass, some Al foil and a 9kV NST. But I won't pursue the SO2 + O3 --> SO3 + O2 route unless all else fails. That includes trying a Pt catalyst as well. I'll get a very <b>expensive</b>:mad: piece of Pt wire in 2 weeks at the earliest, so you have plenty of time beating me to it.

And yes, you are insane. I get fixed ideas too, and I'm a certified whacko. Logically, that means you are one too. :)

I'd recommend an NST instead of a flyback, though --- it's wattage is much higher :)

Tacho - 30-3-2004 at 09:20

Quote:
Originally posted by axehandle
(snip)
And yes, you are insane. I get fixed ideas too, and I'm a certified whacko. Logically, that means you are one too. :)

That damm mercury! I knew it!
Quote:

I'd recommend an NST instead of a flyback, though --- it's wattage is much higher :)

Well, maybe, but I'm 97% sure that wattage is not important to get ozone. You need high voltage, but very very little current.

Marvin - 1-4-2004 at 20:32

Maybe we should call you Tacho the mad Hatter then. Blame the mercury all you like but if you are 97% sure by my math that gives you 3% common sense. ;D

In a well built system power is the limiting factor. You are making a high energy molecule from low energy ones, and wasting a fair amount of energy on the way. A commercial generator I based my math on for the nitric acid numbers consumed 600W and produced 30g of ozone an hour. The concentration of ozone was 6% in oxygen.

For the classic setup of a silent electric discharge a neon sign transformer would work very badly, prodicing something like 500 times less ozone than a 10W flyback operating at 20KHz and the same voltage into a small area (read conventional sized) silent discharge.

Though a corona discharge will produce less ozone per watt, you can even use DC, so its only how much power the transformer can produce and how large an area of discharge you can make that really matters. Keeping things cool, including the discharge, may require a very large box.

One way that might work to see if you are generating useful amounts of ozone would be to dissolve a tiny amount of an organic black dye in water, and bubble the ozone in until it goes clear. I'm open to better suggestions though.

Tacho - 2-4-2004 at 03:49

Thank you so much!
I learned a lot from your post and I feel much more enlightened about this subject now!
We are very lucky to have someone like you to teach us how to do things in the proper way!!
Keep up with the good job, old pal !!






Marvin, Marvin... I’m not biting your bait!

Organikum - 2-4-2004 at 05:57

The attached .pdf might be of interest here. :D

Attachment: ozone_generator.rar (37kB)
This file has been downloaded 1242 times

Organikum - 2-4-2004 at 07:43

"Doppelfeldozonröhre"
aka: "doublefieldozonetube"

German patent DE886896 (attached)

The patent is in german but the drawing is quite self-explaining. They claim doubled yields of ozone by this design - the idea is convincing: There is the outside as the inside of the highvoltage/highfrequency tube used - doubled efficiency - easy.

If there are problems in understanding the patent - ask and I will translate the main part.

Attachment: DE886896.djvu (51kB)
This file has been downloaded 932 times

Tacho - 4-4-2004 at 15:57

This is the new version of an old ozone generator I've built.

It turns water with a drop of blue ink from deep blue to almost clear in about two minutes.

It doesn't have the beautifull visual effects my old one had, but it seems to be more efficient in producing ozone.

It avoids the complicated glassware.

Thanks you for the input Organikum.

marvinator.jpg - 58kB

Marvin - 4-4-2004 at 23:57

Marvinator.
*chuckles*

With some very dodgy math my wild guess would be not above a gram of ozone a day.

The only thing I can suggest, would be to dilute some 3% peroxide to a known lower concentration, and see how much of that is needed to clarify some of the ink solution.

Since the ink is organic its quite possible it is being oxidised multiple times, thus making the error rather large but I still cant think of a better way.

How well do you think the acrylic will stand up to the ozone?

Tacho - 5-4-2004 at 03:19

Oh! Marvin, Marvin, you noticed!

I’m soooo honored!

You think the acrylic won’t hold to the ozone? Well, you should see what happened to the latex tube I used in the output of my last generator! Do you know any uses to latex goo? I'm sure you do!

I don’t care what happens to the acrylic.

I have so much to learn from you! Please, please, keep teaching me!







BTW, I did use the ink discolouring test. Thanks for that.

BASF - 5-4-2004 at 09:16

Without knowing too much about the ozonizator, i´m able to type in a few words in google and provide a link...maybe that helps a bit.

http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3...

I also read that electrolysis of cold concentrated sulfuric acid is used in industry...

Well gee golly BASF.......

Hermes_Trismegistus - 5-4-2004 at 09:21

that's MUCH easier than the aluminum foil in a cup method, maybe I'll whip one up between breakfast and lunch! :P



Edit "no offense intended eh! just acerbic humor"

[Edited on 5-4-2004 by Hermes_Trismegistus]

Tacho - 5-4-2004 at 10:26

The potassium iodide->Iodine as a ozone measure is new to me! I like that.

and probably....

Hermes_Trismegistus - 5-4-2004 at 10:46

you could use any halide salt to halogen as a quantitative test

Tacho - 5-4-2004 at 11:13

Maybe, but iodine has strong color and low volatility(sp?). Chlorine does not make sense and bromine will evaporate quickly.

I guess it would be dependant on availibility.

Hermes_Trismegistus - 5-4-2004 at 13:49

Flexibility is always a good thing. Chlorine could be an odour/colour (of emitted gas) dependant test at it's most basic level, although I'm sure there are other smple ways to monitor chlorine evolution.

In fact, the reaction itself might be useful for other things.

note* I'm not disputing the suitability of KI for quantitative analysis. It is, of course, the reigning champion for many procedures.

Mr. Wizard - 5-4-2004 at 15:20

A general test for oxidizers is KI/starch paper, slighty moistened with dilute HCl. In the presence of an oxidizer Cl is liberated which liberates Iodine which reacts with the starch to make a distinctive blue or black stain. Ozone should liberate the Chlorine from HCl and set things in motion. I have seen it work with organic peroxides, nitrates, hydrogen peroxide, and bleach. I have not tried it with Ozone, but I could guess it would work.

Tacho - 5-4-2004 at 15:41

Guess what? I did a test with KI solution and another with NaBr solution. KI goes from clear to tan in about 2 minutes. Nothing happens to NaBr.
It seems ozone is not a strong enough oxidizer to release bromine.
Shame. It would be a nice way to make elemental bromine.

The_Davster - 5-4-2004 at 17:20

What is wrong with bubbling chlorine through to get the bromine?

Marvin - 5-4-2004 at 20:06

Hermes, yes its not simple, but on the other hand it is producing over 2 orders of magnetude more ozone than the corona wire chamber, and this is still an order below what would be needed to make N2O5 from a 1kw arc furnace NO2 source.

Tacho, thanks are not needed, a small temple in my honor will be quite sufficiant.

You might not care about the plastic, but if it is reacting this will be reducing the output of ozone. Teflon tape might help.

If you can standardise some thiosulphate the reaction with iodine followed by titration will be a much better way of determining ozone. Iodine itself is not particually strong coloured (for the concentrations used) but iodine/soluable starch peforms very well.

To try for bromine acidify the bromide solution first with HCl.

Tacho - 6-4-2004 at 03:35

Now, that’s a beautiful post Marvin!
It expresses ideas, points of view and even has sense of humor.
Don’t you hate when people are rude, abusing and patronizing? Doesn't it spoil the fun when people express their point of view in an arrogant ‘I know all” way?
We are lucky not to have such people here!

I like the HCl idea very much. But lets start with a little shrine.

Tacho - 6-4-2004 at 15:28

No, HCl+NaBr does not work. I bubbled it for 20 min.

It was a good idea, though.

I presume that, if any bromine was formed due to ozone, it was carried away by the air stream.

I added some H2O2 (20%) to the solution and plenty of bromine was formed. Not enough to precipitate, but it turned the solution brown.

rogue chemist, there is nothing wrong about using chlorine. Have you ever done it?

The_Davster - 6-4-2004 at 17:13

Yes, once. I had a tiny(10mL) bottle of 10%KI solution from an old chem set. A few seconds later after bubbling Cl through I got a small amount of I2. When I posted earlier I had misinterpreted the earlier posts and I some how thought the thread had turned into one on extracting halogens.

I'm back!

axehandle - 8-4-2004 at 13:16

But what is this junk?
Quote:

For the classic setup of a silent electric discharge a neon sign transformer would work very badly, prodicing something like 500 times less ozone than a 10W flyback operating at 20KHz and the same voltage into a small area (read conventional sized) silent discharge.

Though a corona discharge will produce less ozone per watt, you can even use DC, so its only how much power the transformer can produce and how large an area of discharge you can make that really matters. Keeping things cool, including the discharge, may require a very large box.


Conclusion: An NST would work best, but in the same time an NST wouldn't work best?

<b>Come on</b>, Marvin, even you <b>must</b> be able to screw with logic better than this. You don't even manage to confuse <i>me</i>, which normally is very easy.

BTW: Very nice setup, Tacho. The acrylic "problem" is easily solved by replacing the plastic with sandblasted glass, glued in place by a glue that passivises when oxidized. But I'm sure you've figured that out already.

Tacho - 9-4-2004 at 09:23

Wellcome back axe!

I just found out that my marvinator is not good enough to make H2SO4. You don't have to live in fear anymore!

I burned about 3 grams of sulfur in a 100ml glass flask, in the output line of ozone, bubbling the result gas in water. pH only went to 5 after about 15 minutes. Guess is just sulfurous acid. Any decent ammount of sulfuric acid would make my 10ml of water have a much lower pH.

I attach a drawing if anyone feels lucky:

gasflow.jpg - 7kB

Marvin - 11-4-2004 at 03:43

Tacho,

Dont you just hate it when half a decade of helping people with chemistry gives you a patronizing tone. Doesnt it spoil all the fun when most people you help dont bother looking up anything in a library, or even think about the problem logically?

We are lucky not to have either of such people here!

I'm a happy go lucky person with both the valueable gift and heavy burden of being never wrong. Ocasionally the universe makes mistakes, which is where discrepancies come from, and when I talk to god *I* am the one answering *his* questions. Unfortunatly axehandle has not learned this yet and its almost a shame to spoil the happy feeling he has from thinking he's seen a mistake. The sooner he does learn this however, the sooner he can help you with the shrine.

axehandle,

The two methods avoid the same problem, but they are different. In passing current through the air at atmospheric pressure, the flow tends to collapse so a single point on both electrodes and move within a very small volume of ionised gas. A spark, or arc. This is hot gas as a result, and so the conditions are bad for production of ozone. What is needed for ozone is a low density of current through the air. In the corona method, a very fine wire or sharp edge 'sprays' charge into the air by virtue of its high electric field gradient. This is constant over its length and so long as certain voltages arnt exceeded for a given arangement, dielectric breakdown does not occur and sparks/arcs do not form. This is electrically just a discharge tube connected to the power source and so can use DC, or AC, and power dissuptated is largly independant of the frequency, if AC is used.

The classic silent discharge method uses electrodes that are insulated, usually by glass tubes. A spark or arc cannot form because the only current flowing is that formed by induction on the surface of the insulator. The discharge is forced to be very low density, and is constant throughout the surface area of the tubes. Unlike the corona wire though, electrically this is a discharge tube in series with a low value capacitor. DC cannot be used and the power dissupted in the gas is proportional to the frequency of high voltage applied, and thus the frequency proportional to the maximum acheievable formation of ozone.

The NST is usually rated much higher than a flyback circuit in terms of power, but a flyback circuit produces high voltage at 10's of kilohertz, wheras a NST uses mains as its input directly and thus outputs at 50 or 60Hz typically, so while it is rated at much higher power, in the silient discharge method the flyback circuit will usually produce a lot more ozone.

A flyback circuit has no advantage over a NST on the corona wire method.

Sand blasted glass might catalyse decomposition of the ozone.

axehandle - 11-4-2004 at 12:20

Quote:

Wellcome back axe!

Thanks. It's good to be back, apart from the annoying fact that all the interesting stores are closed due to the easter holiday. I won't get any Al tubing until Tuesday, sigh.
Quote:

I just found out that my marvinator is not good enough to make H2SO4. You don't have to live in fear anymore!

If anything I'm sorry that it didn't work. I don't think of this as competition, but as an internationally distributed effort based on cooperation.
Quote:

I burned about 3 grams of sulfur in a 100ml glass flask, in the output line of ozone, bubbling the result gas in water. pH only went to 5 after about 15 minutes. Guess is just sulfurous acid. Any decent ammount of sulfuric acid would make my 10ml of water have a much lower pH.

Sounds correct. Pity. The method would probably work if using multiple powerful ozone generators using pure O2 as the input.

On the bright side, I'm going to use your fantastic salt thermostat for the exhaust heater. I'll tell you how it goes.

Tacho - 12-4-2004 at 14:58

Marvin,

I don’t think it’s God you are talking to. But if you think it is, it’s OK. Remember how we started this thread? Wacko, mercury?... See? It’s all right! You are among friends here. We are here to listen and understand! You can open yourself to us. Don’t worry about being a bit old, we are not very young either! We can make you young at heart like us!

Your last post explained very well why we need AC for the usual glass made ozonizer (Siemens). I must warn anyone trying to built one that some flybacks have built-in rectifiers. I must also tell that my flyback HV circuit can make a spark jump a 1,5 cm gap easily, so, I estimate the voltage in 15kV(this is empirical, Marvin, don’t make a fuzz, ok?). Flyback circuits can be pushed way above that; read Sam Barros page linked in previous post.