## H2O2 by ozone -- The slow method.

axehandle - 1-10-2004 at 12:11

By my calculations, 0.24m<SUP>3</SUP> of ozone should suffice to convert 1dm<SUP>3</SUP> of water to 35% H<SUB>2</SUB>O<SUB>2</SUB> solution, given 100% efficiency.

I have no idea of how efficient the ozone generator I just invented and whipped together is (attaching a drawing), but this is probably going to take a while. The bottle contains 0.5dm<SUP>3</SUP> of water.

I'm feeding the thing with 9kV AC, BTW.

Notice the blue light from the corona discharge:

EDIT: *cough* *cough* No, it's not 100% efficient. I think I have to solve the problem of reacting tail ozone before running this for long.

[Edited on 2004-10-1 by axehandle]

hodges - 1-10-2004 at 15:23

Unless you use pure oxygen (vs air in the room), how do you know that you don't get HNO3 instead of H2O2?
axehandle - 1-10-2004 at 15:25

It's not a plasma discharge but a corona discharge. No arc -- no NO<SUB>2</SUB>.
FrankRizzo - 1-10-2004 at 21:24

It appears that corona discharge (if the energy involved is high enough) will produce NO<sub>2</sub>.

http://www.fysik.uu.se/doktorand/doktoranddagen/Abstracts/Ma...

NOx production in spark and corona discharges

Mahbubur Rahman, Nils Rehbein, Vernon Cooray

Division for Electricity and Lightning Research, Department of Materials Science
The Ångström Laboratory, Uppsala University, Uppsala

Abstract

This paper presents an experimental study on the production of NO and NO2 as a function of electrical energy in
laboratory sparks and corona. The results show that both the NO and NOx yield increase almost linearly with the
energy per unit length of the discharge. From the data, it is estimated that the spark discharges with energy in the
range of 0.5-2.0J....

[Edited on 2-10-2004 by FrankRizzo]

JohnWW - 2-10-2004 at 01:40

I would not do it with ordinary air - only with pure O2. Besides, with air, nitrogen oxides are thermodynamically favored over O3 production.

John W.

S.C. Wack - 2-10-2004 at 11:25

Oh, please, people have been using ozonizers with air for a very long time. Of course one can get higher and faster yields with O2, but the O3 yield is still very much higher than the NxOx yield. Given low voltage/residence time, of course.

http://www.orgsyn.org/orgsyn/prep.asp?prep=CV3P0673

axehandle, exactly how are you planning to get H2O2 from this?

axehandle - 2-10-2004 at 12:03

 Quote: axehandle, exactly how are you planning to get H2O2 from this?

By bubbling the O<SUB>3</SUB> through cold water. Should work, according to something I read somewhere.

rikkitikkitavi - 2-10-2004 at 22:05

but first you will ozidize any organic matter so it would be best to seal the vessel so no dust can enter it. Also, have you considered the fact that ozone is very toxic.

also, you should use deionized water, otherwise the H2O2 will decompose due to dissolved metals e t c.

Fortunately the odour threashold is about a magnitude lower than the lowest level where ozone starts to have physiological effect. But perhaps you will not have a winter cold when this is operated.

Marvin - 3-10-2004 at 07:56

I agree that bubbling ozone into water should form trace amounts of hydrogen peroxide, but it is also my understanding that ozone destroys hydrogen peroxide.
sarcosuchus - 3-10-2004 at 12:54

this is something i do know from hands on research your going to get hno3 unless you use pure O2 and pure h20 (see my post on plasma cutters).....real dumb thought but if you burned H2 with O3 in argon with a excess of O3 would it favor H2O2 if it was cooled rapidly say 0.1 sec ???
Marvin - 3-10-2004 at 18:56

If you use dry air you will get a proportion of nitrogen pentoxide, this can be small compaired to the amount of ozone though.

An ordinary oxyhydrogen blowpipe flame set against a piece of ice, the water run off will contain hydrogen peroxide. Enough for a chemical test at least. I doubt when it comes to combustion ozone will make much difference unless it is in great excess and the heat is just used to decompose it with water vapour. I dont see any of these methods producing useful amounts of peroxide.

### Absorbtion train

Hermes_Trismegistus - 4-10-2004 at 07:20

recently read about something called an absorbtion train that old-timey chemists used when trying to dissolve gasses in liquid, It simply consists of jumping the gasses that bubble off the top of one flask and bubbling them through another flask.

actually.....

lefty - 24-11-2004 at 10:16

There's a better way to build an ozone generator.

I used a leibig condenser (but any glass tube would do) with aluminum foil wrapped around the outside and a steel rod through the column in the middle.

Hooked up to a 15,000 V step-up transformer, the whole thing glowed purple.

I used an aquarium pump to force air into the cooling jacket of the condenser.

You should know that using air, only 1 to 2 % by volume of ozone is generated. If you use pure O2, you can get up to 3 or 4% according to the literature I've read on it.

I've done a lot of research and experimentation with Ozone, I'm not sure if it will cause the conversion of water to H2O2 - don't know. I do know that it will destroy organic compounds dissolved in the water and oxidize/change/destroy other dissolved solids (nitrates for example)

It is used as a substitute for chlorination in some water treatment facilities. I toured one once. The ozone generators are glass tubes about 3 to 4 inches in diameter with an Ag film on them. The spark gap in these industrial generators is on the order of 1 millimeter.

Just in case you weren't aware, ozone can destroy anything rubber in your house, so watch your refrigerator seals for example if you're experimenting with Ozone. It also damages the cilia in your lungs - can be pretty nasty stuff.

Formatik - 5-5-2009 at 23:04

This method won't work. Ozone can not be combined with H2O to obtain H2O2. Gmelin mentions no H2O2 formation occurs between O3 and H2O. Ozone and H2O2 also decompose each other: O3 + H2O2 = 2 O2 + H2O. Where interaction of O3 and H2O2 is known to form dihydrogen trioxide (H2O3), which decomposes rapidly, a bit more about the intermediates here.

I've also tried it. Having bubbled ozonized air into regular water for about 1-2 hrs time, then adding the resulting solution to KI gave no brown/yellow discoloration (no H2O2). Even in very dilute amounts H2O2 still discolors KI.

Another method to H2O2 is using direct current against water, here is a paper which describes using DC on water utilizing a carbon felt cathode and RuO2 coated titanium anode to form H2O2, though apparently in low concentration, around to or a bit lower in concentration than when forming H2O2 from ice and an oxytorch flame.

Saber - 8-5-2009 at 11:45

For ozone generation, yields are greatly increased by using a negative corona discharge.
Keep temps low, to maximise yield, however i advise passing through a calcium/sodium peroxide washing tube to remove NOx.
I have used O3 in the past to oxidise SO2 to SO3, until i built my glass contact proccess...

hissingnoise - 8-5-2009 at 12:45

Being able to prepare oleum by the contact process must be a real buzz---what catalyst do you use?

DJF90 - 8-5-2009 at 13:06

Yes please post complete details for us! It would be a remarkable step for some of us to be able to make conc sulfuric and oleum! I intend to do this myself at some point but havent got the time or money at the moment How do you combust the sulfur? In the glass? Oxygen/Air inlet? What kind of glass?

Formatik - 8-5-2009 at 14:09

With a professional type ozonizer there might not be any nitrogen oxides, at least not by me (moist litmus paper won't turn red after being held in the stream for some time, no NO2 odor either). Also according to some literature O3 won't react with dry SO2. Liquid O3 and SO2 don't react either.

[Edited on 8-5-2009 by Formatik]

Saber - 8-5-2009 at 23:19

Preparing Oleum on tap is extremely useful however there is only so much oleum you can use, so I never make more than a liter a day, if that,
My catalyst of choice is supported V2O5, obtained from purifying and activating pottery grade V2O5.
My sulfur burner is the only non glass item in it. It is manufactured from Stainless steel and I have found it resists attack perfectly. The rest is made of Borosilicate glass. I chose Boro because it is easy to work with.
@ Formatic- simultaneously bubbling a mix of SO2 and O3 through cold water produces H2SO4, proven fact, The only thin I have against this is expense and the fact it produces high sulfur oxoacids.

hissingnoise - 9-5-2009 at 07:20

 Quote: Originally posted by Formatik With a professional type ozonizer there might not be any nitrogen oxides, at least not by me (moist litmus paper won't turn red after being held in the stream for some time, no NO2 odor either). Also according to some literature O3 won't react with dry SO2. Liquid O3 and SO2 don't react either.

AFAIK, all airfed ozonisers produce some NOx in moist air---moisture raises conductance (H2CO3) of the air, producing hotter microdischarges to the point where (some) N2 bonds are broken.
Some pro units have an integral air-dryer to overcome the problem. . .

As to O3/SO2, I think the oxidation is catalysed by a trace of H2O and possibly a high temperature.

bquirky - 9-5-2009 at 07:44

chould you not dry normal air first through sulfuric acid or sucking it through a domestic frezer ?
hissingnoise - 9-5-2009 at 07:51

 Quote: Originally posted by Saber Preparing Oleum on tap is extremely useful

To me even that's an understatement. . .
If you could offer it for sale everyone on this board would be potential customers.
But fuck it, we live in a chemophobic world.
Any chance that you might post a few pics. . .

Saber - 9-5-2009 at 08:26

At current i will not be able to upload any pictures as i do not own a camera, I will though asap.
Like you said though Hissingnoise, i wouldnt dare post Oleum, unless you pay ridiculous Hazmat fees,

hissingnoise - 9-5-2009 at 11:54

We're looking forward to seeing them, Saber---even cellphone pics. . .
Formatik - 9-5-2009 at 13:23

 Quote: Originally posted by Saber @ Formatic- simultaneously bubbling a mix of SO2 and O3 through cold water produces H2SO4, proven fact, The only thin I have against this is expense and the fact it produces high sulfur oxoacids.

It needs the H2O for the reaction I know this that's why I said dry SO2. Thus, SO3 isn't a product.