I would like to experiment a little with ozone gas. I see many ozone generators on eBay. For just a few tens of euros there are devices, which are
stated as having an output of 10 grams per hour, or even 20 grams per hour, just from air. An example of such a generator is this:
Is this really 10 gram per hour? I hardly can believe that.
Another issue with these devices is that the ozone is blown out of the device with a fan. Not easy to collect the gas in that way.
There also are other types of ozone generators, with a small output tube, which delivers the gas. With these tubes, it is possible to bubble the gas
through water.
Some devices also need an external slow air pump in order to get an air flow. I assume that a small aquarium pump can be used for that.
What if I would pass in pure oxygen slowly from a gas cylinder? By how much would that increase the ozone output?
Any advice would be welcome. I have the feeling that nearly all devices out there are crap and not useful for scientific experiments and a waste of
money.clearly_not_atara - 2-3-2021 at 13:40
Quote:
What if I would pass in pure oxygen slowly from a gas cylinder? By how much would that increase the ozone output?
Well, in principle, it should increase O3 output by a factor of 5 (100% / 21% ~= 5). But in practice, it could also deactivate or destroy the device
since electrical equipment may be designed with wide or narrow tolerances as
the manufacturer feels appropriate.
The real question to me is: what concentration of O3 comes out, and will it dissolve in your rxn mixture? I've generally been under the impression
that the O3-alkene reaction is so fast that bubbling low concentration ozone through a solution of alkenes is enough for ozonolysis, but for other
ozone reactions, it may not be so simple.
Anyway, suppose that you blow air through a tube about 10 square centimeters (1-2 square inches; 0.001 m^2) at 1 meter per second. That's 3.6 cubic
meters of air per hour or about 4.4 kilograms which means about 900 grams of oxygen pass through the device. Ten grams per hour would be about a 1%
conversion rate of O2->O3, which sounds a bit high but by no means impossible, especially if the corona is larger or the flow rate faster.unionised - 2-3-2021 at 14:08
The people who sell power amplifiers used to quote "peak music power output" which was calculated by measuring the real power output and multiplying
by as big a number as they thought the customer would believe.
I gather that the ozone maker adverts do something similar.
The figure they quote assumes that you are running pure oxygen through the device.
If you use air then the yield drops dramatically.
I'm afraid that 21% of the nominal yield is optimistic unless you carefully dry the air that you feed into the gadget.
Moisture in the air reduces the yield significantly..
Fyndium - 2-3-2021 at 15:11
Possible idea is to put the ozonator in a sealed box and pump air into it with air pump and lead an output tube to desired use. Would be also easy to
dry by passing through CaCl2 trap.
So the ozonator fan and speed are eliminated and instead you control it with your air pump feed rate. The ozonator would circulate the air in the box
with the fan, keeping up a concentration that depends on pumped air. Likely also pure oxygen could be supplied conveniently.
Likely the numbers are a bit high what Chinese state, I have a small, 20x30cm box ozonator that was sold cheap and stated to give 28g/h of ozone.
Don't know how much it is actually, but it can easily deodorize a 25m2 space in a few hours, better overnight.Mateo_swe - 2-3-2021 at 15:23
The figures they state on devices on ebay and similar places is under ideal conditions, using pure oxygen, low temperature and for short run time.
I have bought one of those Ozone generators that uses ceramic plates and its specified output according to the seller is 48 grams/hour.
If i get a few grams/hour out of it i will be happy.
The problems is keeping the device cold when its producing hi-voltage corona that is heating the plates.
Supplying cold air or cold oxygen might work to get longer on-times.
Ozone generators for chemical ozonolysis often uses glass tubes with conducting liquid as anode/cathode, like a double jacketed condenser with
conducting liquid on the inside and the outside of a air gap where the corona forms.
This way the corona dont touch anything except glass walls and the conductive liquids are easier to keep cool so thats a brilliant idea.
I add a PDF displaying this kind of ozone generator and a few other ozone PDFs if anyone wants to look.
Attachment: ozone_generator.pdf (48kB) This file has been downloaded 264 times
They have a hose fitting at either end, but no outer housing so cooling the discharge tube is more practical.
Some come equipped with a finned outer sleeve and these are claimed to not need additional cooling (at least by the guys who sell them).
The ones without the finned sleeves require forced airflow around the tube for cooling.
(Or maybe a cooling fluid non-conductive enough to take the voltage? Probably get better cooling that way if it works)
I don't know if the ratings I've seen on Ebay are accurate, but one posting said the common 6 gram per hour ozone generating tube gives the rated
output on 2 liters of dry oxygen per minute. If this rate of oxygen usage isn't an expense problem then I'd say try using your oxygen tank, but if not
I'd suggest pre-dried air as a cheaper (but lower yielding) way to go.
Either way I would strongly recommend testing the output.
I think oxidizing Iodine and titrating for iodate is a common way to test this,, but there are probably other options.
It seems many of the organic reactions using ozone are pretty picky about the exact amount added and the rate of addition.
However if you're just making ammonium nitrate or sulfuric acid such considerations may be less critical.
Edit: it is a 6 gram per hour, not 3 GPH, that was listed as using 2 liters of oxygen per minute.
[Edited on 3-3-2021 by SWIM]Mateo_swe - 2-3-2021 at 16:09
This PDF, "The Definitive Guide to understanding Ozone" contains useful info on ozone.
For example, ozone dissolved in water have very short half life, and at higher temperatures, 35°C its only 8 minutes while at 15°C the half life is
30 minutes.
In air ozone is more stable.
I had to zip it as it was too large to attach (13Mb).
Below are some ozone generation efficiencies in g/kWh input power.
"At present, the typical commercial efficiency of ozone
generators is 90 g/kWh using dry air and 180 g/kWh using
oxygen [1]. These practical efficiencies are low compared to
the theoretical efficiency of 1200 g/kWh, with 85% of the
energy being lost as heat. In attempts to increase the ozone
yield, some investigators have researched reactors cooled by
liquid nitrogen [6]–[7]; the ozone efficiency achieved was in
the range of 400-600 g/kWh."
[Edited on 3/3/2021 by wg48temp9]Dr.Bob - 3-3-2021 at 13:05
I have used very old models of lab ozone generators, and they all make less tan expected, we used oxygen as the inlet gas, and used cold (~-78 C) DCM
as the solvent for the substrate, partly to avoid any fire risk, which is a real issue. You have to be careful not to let the ozone accumulate near
the electronics, as that can cause a fire. Even in a good fume hood, I could always smell traces of ozone, like a lightning storm. But when you
see the blue color, at least you know that you are done. That and a Birch are some of the few blue reactions I have ever done. But count on a
slow output of ozone and a low solubility so much goes up the stack.j_sum1 - 3-3-2021 at 13:42
Tdep had many of the same questions and did a number of experiments to find the answers. Air vs oxygen. Claimed versus actual output. Collection.
Cooling. Worth watching.woelen - 3-3-2021 at 23:59
I found out that there are so-called oxygen concentrators. Not really cheap, but a limitless supply of 90+ % oxygen, so maybe I buy such a device
anyway. I found such a device for appr. 350 euros, which can deliver 1 liter of 90-93% oxygen, or 2 liters of 55-60% oxygen, or 3 liter of appr. 40%
oxygen per minute at an output pressure of 0.2 - 0.3 bar over atmospheric pressure. These devices are meant to be used by COPD patients, but nowadays
they are also sold to people who have COVID-19 complaints.
With such a device I could have much higher ozone output. Maybe 1 liter per minute is not enough?Dr.Bob - 4-3-2021 at 08:04
I have seen those type of concentrators used for similar purposes, including by glass blowers for oxypropane torches. They should work fine, You
might find one used for less, there was a very large one for sale here on the web for 1/2 of the normal price. They should work fine, I would try to
keep the flow moderate, and even doubling the percent of oxygen will help a lot. Just figure that you might be about 10-20% of the rated capacity of
the ozone generator as a starting point, and then you can just run the reaction as long as needed. I have run large ones for hours before. You
just need to see if the one you get is rated for continuous use or cycle it on and off as needed. Good luck.
If you are trying to make an aldehyde from a double bond, which was my main goal, then quenching when cold with DMS is ideal, but stinky. You may be
able to find a higher MW disulfide, but I would just quench and then bubble nitrogen through the reaction flask and put the output into bleach to
kill the smell of the excess DMS. I used symmetrical olefins to generate small MW aldehydes a few times. But also great for oxidizing protected
amino acid alcohols into their corresponding aldehyde as well as other tricks. Can also make diacids from cyclohexene and similar substrates. A
cheap oxidant if you can use it well.woelen - 5-3-2021 at 14:10
I found an even cheaper device for oxygen production. These devices produce oxygen and then the gas is bubbled through water before it is passed to
the outlet. The water is used to make it humid again, because immediately after the concentration of the oxygen, it is very dry (water, nitrogen and
CO2 are removed), and before it can be inhaled it must be made humid again. For my purpose, it is simply a matter of not filling the water tank
through which the oxygen is bubbled. This leads to a dry oxygen stream and the flow will most likely also be somewhat more steady.
The next step is adding an ozone generator. I will go for a kit, with separate power supply and tube. With such a kit I do not have to deal with a
complete apparatus of unknown build. The tube can be cooled with an external fan and these tubes have an inlet and outlet. I simply lead the oxygen
from the concentrator into the tube and then in the output I have oxygen with a little ozone in it. Such kits are quite cheap, they are less than EUR
50.
If the ozone project is a failure, then the oxygen concentrator on its own is a nice addition for my lab as well. Having 93% oxygen at hand with a
push of a button is a nice thing.zed - 6-3-2021 at 23:14
Well. I've looked into Ozone, but I never figured out anything I could use it for.
Great for cleaving interesting olefins, and thereby producing desirable aldehydes, but I can't use that service anymore.
Some of the guys have claimed they can produce higher Ozone concentrations by electrolysis, or Chemically.
Might be true.
Seems to me, Oxygen concentrators will be much cheaper, next year. At the moment, need is great, and supply is limited. Next year, perhaps the
market will be flooded with un-needed, slightly used units.
I sure hope so.
I looked into it recently, and Ozone couldn't answer my recent Oxidation wants.
Other agents might. Apparently, they react Ozone with water, to form hydrogen peroxide, then they react the peroxide with Sodium Borate, to form
Sodium Perborate, then they dissolve the Perborate in glacial acetic acid, to perform interesting oxidations. Sure better than what I used to do, in
the old days.
At least I hope so. Everyone hypes the method, no one has mentioned if there is danger involved.
Formerly, when I used concentrated Peroxide in concentrated Formic Acid, the messages were clear. There was some danger involved. Handle with
caution.
Something to be said for buying a Hydrogen Generator. Sometimes working used units can be purchased for $500.00 or so US. At least, here in the
States they can be. A decent one can produce 500 MLs per minute of pure H2.
And, if the generator is producing 500 MLs/Minute of H2, then.... It is sending 250ML/Minute of pure O2... Someplace. And, I want all of it.
I wonder if there are Scientific Units that allow you to tap both gases?
250ML O2/min x 60= 15000 ML/hour. Ummm. Two hours= 30000 MLs Pure O2. Or, if you could convert it to Ozone with a 100% yield (impossible) 20,000 ML
O3 or about a Mole of O3(I rounded up). So, how many grams? ~48
Ummm. Yes. I can see why this would be slow. Though it would appear a hydrogen generator would be a crappy O2 supply. Even with a much better
source, it might still be slow.
Still, I would think about it. Not because it is practical, but because I really want a Hydrogen generator. Hydrogen I understand. Hydrogen is
useful. Oxygen is just the icing on the cake. Also an excellent way to accidentally start fires.
Now, if I could produce copious amounts of Nitroethane via the action of Ozone on Ethylamine.... Or, Alanine... My interest might be amplified. I
miss Nitroethane.
OK. Now I'll go back, and carefully re-read all of your posts.
I like to talk, but I've noticed, that I only learn things, when I listen.
[Edited on 7-3-2021 by zed]
[Edited on 7-3-2021 by zed]zed - 7-3-2021 at 00:14
Ummm. Now, on different note. Some folks suggest electrolysis to produce not just H2, but O3.
So, my dream Hydrogen generator, produces not just Hydrogen, but at the flick of a switch...O3. Lots of O3, not this sissy stuff we have hitherto
talked about.
Man, I really like the idea, I just hate the origin of the paper. India.
Ummm. Yeah. There is stuff out there. Practical applications? Electrolytic Ozone, chemists can actually use for practical lab preparations? I
don't know.
[Edited on 7-3-2021 by zed]woelen - 10-3-2021 at 08:14
I received my oxygen concentrator. I must say that it works quite well. It runs cool and the amount of noise it produces is acceptable. The flow can
be adjusted. At its lowest setting it produces appr. 1 l/min, at 85% oxygen, concentration slowly increasing if the device runs for a few minutes (it
can go to 93% if it is allowed to run for 10 minutes or so at lowest flow setting and then remains at 93%). At 2 l/min the concentration drops to 75%
- 80%. Concentration gradually decreases with increasing flow. I did not test the concentration at its highest flow setting.
For medical application, the device only is of limited use. Real oxygen demand for people with severe COPD can be several liters per minute at nearly
100% concentration. This device certainly does not reach that. But its price of a little over EUR 200 also is very low, compared to the price of real
medical devices (EUR 2000 for the smallest one to over EUR 5000 for really serious devices). The device I have has a constant flow, while the real
medical devices sense when oxygen is inhaled and only deliver oxygen during the inhalation phase of breathing. This allows much more efficient use of
oxygen and higher flow when it really is needed.
For my application all of these extras are not necessary. I already did a few nice demos with big beakers of oxygen, in which I burned sulfur, wood
and all kinds of things. Fun and kids love it (especially the burning sulfur is really cool in almost pure oxygen).
I think that I will operate the device at 2 l/min (with appr. 75% concentration) in combination with an ozone generator. I did not yet find a nice
ozone generator. I read bad reviews about the cheap ozone generators. They run very hot, many of them cannot run continuously and overheat when
running for more than 5 minutes. I consider building an ozone generator myself. You can buy kits on eBay with separate tubes (quartz tubes with inner
and outer conductor) and high frequency high voltage power supplies. There even are kits with metal coolers, which can be mounted around the tubes.
With an external fan it should be possible to keep them running continuously without melting the ozone tube. To be continued . . .zed - 11-3-2021 at 08:47
Brings to mind, the un-utilized high voltage transformer, residing in most non-functioning microwave ovens.
since electrical equipment may be designed with wide or narrow tolerances as
the manufacturer feels appropriate.