H2O2 ways to concentrate 3% ?

[A-BOMB]

I was wondering if you could use electrolysis to break down the water in the hydrogen peroxide to concentrate it to a higher persentage?

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live by the bomb
die by the bomb

[kingspaz]

good try but the electrolysis will also break down the H2O2 into H2 and O2.
i believe its possible to separate by difference of freezing points. if you lower the temperature of the solution to between 0.1 and 0.3 *C then the water will freeze but the peroxide with a slightly lower freezing point will not(i think its 0.4 or 0.6 - can someone tell me please?). anywasy you can pull the ice out which removes water therefore raising H2O2 concentration.

[Mr Cool]

Why bother? 3% works for organic peroxides. Concentrating it will make the reaction a bit faster, but it isn't worth it.

[A-BOMB]

Maybe I could distill them or is there any chemical that would breakdown the water and not the h2o2? And I tried the freezing idea and the h202 gets froze in the h20 and thats bad.

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live by the bomb
die by the bomb

[Mr Cool]

Unless you're making rocket fuel DON'T BOTHER!!!
Vaccuum distilation is a possibility.

[A-BOMB]

Well, I just wanted to concentrate it for AP.
So any more ideas to concentrate H2O2?

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live by the bomb
die by the bomb

[Anthony]

In any purification process, you will loose some H2O2. Therefore you will actually get LESS AP for a given amount of your starting H2O2 solution than if you just used it as is.

[10fingers]

I've concentrated Hydrogen Peroxide by heating it. I did not think at first that this would work but it does.
Put a quart of 3% H2O2 in a glass pot and very gently heat it, just enough so that you can see a slight vapor. Heat until there is an ounce or two left. Takes several hours.
I have gotten the concentration up to around 15% this way.

[BrAiNFeVeR]

How did you measured that percentage ??

[10fingers]

I compared it to some 12% stuff that I bought. The yield was slightly higher.

[Disturbed]

10fingers,
when you boiled down your H2O2, did you get consistent results regarding how much AP you end up with? I have always boiled down my H2O2, starting w/ about 500ml of 3%, to about 50ml of what I assumed is 30ish %. I have tried making a small amount of AP using real 30%, but the yield seemed about the same as my boiled H2O2, so I just use that. I think that I'll prolly try to find some 30% H2O2 locally to verify this. If any of you other ppl have different results using boiled H2O2 vs store bought 30%, I'd like to hear those too!

[A-BOMB]

10fingers, how hot did you heat your h2o2 for it to fume and i thought that heat destroys h2o2?

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live by the bomb
die by the bomb

[BrAiNFeVeR]

Not heat, but UV-light destroys H2O2 (i think) thats why i keep my H2O2 in the dark !!

PS: i still don't understand why you guys want to purify your hydrogen peroxide, since you will always lose some this way ...


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[10fingers]

"ONE" gets consistent results with the concentrated stuff.
You must apply just enough heat so that you see a little water vapor coming off. It takes several hours to do a quart. It is heated until it is about 1/10th it's original volume but I am sure it is nowhere near 30%.
"ONE" has never had good results using 3%. Some of the H2O2 is probably lost in the process but it works.

[This message has been edited by 10fingers (edited August 22, 2001).]

[Disturbed]

There's just way too much controversy surrounding H2O2.. does anyone out there know the actual decomposition temp of H2O2? Is it consistent, or does it change with concentration? I was always under the impression that using conventional means [vaccuum distillation] you could only get H2O2 up to about 60-70%. I do know that it is unstable at room temp, as 30% decays about 3% a year, with the higher concentrations even faster.

[BrAiNFeVeR]

OK, no longer "i have heard" !! I need real facts and numbers for this !
Decomposition temperature and all the works !! (UV-light ?)


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[A-BOMB]

Its somewhere in between 86-90 or so desgrees F I think.

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live by the bomb
die by the bomb

[Disturbed]

A-bomb,
if it is at that temperature, it must take place very slowly.. I'm not all that careful when i boil my H2O2.. I just pour 8 or 10 bottles in a big pot, put that on the highest setting on my stove, and leave it there for a couple hours to boil down to about 1/10th its starting volume. This works just fine for me, I just made some AP using it last nite, and I got a pretty damn good yield, as the whole jar is full or crystals, with only a little liquid in there [leftover water]

[Ezikiel]

How is 100% H2O2 made for rocket fuel purposes ?
I am only aware of a couple of processes that give a concentration of about 30-35%. (Merck's Process)
Actually that is a pretty good way to make H2O2 at home.
but how is 100% made ?

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"Chance favours the prepared mind"

[Mr Cool]

Careful multi-stage vaccuum distillation can get you to >90%
What you need to be thinking about is not decomposition temperature but half-life at a certain temperature and concentration. H2O2 will decompose even at 1% at RTP, but slowly. You can boil H2O2, which happens at a temperature of above 100*C, but this makes it decompose much faster.

So if you boil the 3% H2O2, it will heat to 100*C and the water will start to boil off and it will get more concentrated. H2O2 will also decompose, but at the start the water will boil off at a greater rate than that at which the H2O2 is decomposing. As the concentration of water drops, it boils off less rapidly (in terms of grams/minute), and this means that the rate at which the H2O2 is being conentrated by the water boiling off is reduced due to the fact that the rate of H2O2 decomposition stays the same, but the rate of water boiling off drops. So after a certain point, your H2O2 will get less concentrated again.

Someone please try to explain that better than I have done!

[BrAiNFeVeR]

I Think you did it just fine, so the further in the boiling process, the more accurate the temperature must be to obtain a concentration as high as possible, otherwise the H2O2 will evaporate too.
Simplified, but most of the people around here will appreciate your version more, since it explains it better ;-))


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[Disturbed]

Ok,
H2O2, 100%, boils at 150*c, 30% at about 106, and 3% at just about 100*c.
Also, 10% H2O2 can all boil off due to its highly exothermic reactions w/ any contaminants present.
And lastly, at 63-64% concentration, H2O2 decomposition becomes self-sustaining.. so if it starts to break down, it's all going to break down!

Hope that helps a bit..
found that stuff from www.H2O2.com (http://www.H2O2.com)


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kein mitleid fur die mehrheit

[BrAiNFeVeR]

Now that is the kind of information we need !!
So if I understand this well, there's no way to concentrate it when the original percentage H2O2 is below 3%, as it boils @ 100° C, just like water (pure) does ...
If, on the other hand, you could find something to lower the boiling temperature of the water (adding an alcohol ?) would that work ?? Or would you lower the boiling temperature of the H2O2 also ??
I guess it just won't be all that simple ...


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[kingspaz]

if you add alcohol to the water then when 76*c(think thats ethanols boiling point) is reached the alcohol will boil leaving the water and H2O2 behind.

[Disturbed]

Brainfever,
You should be able to concentrate even low percentages just like you would be able to concentrate sulfuric acid.. as the water and H2O2 don't form an azeotrope like w/ Nitric acid or anything.

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kein mitleid fur die mehrheit

[PHILOU Zrealone]

H2O2 is by its very nature unstable!
Temperature is bad for it since it produces radicals (radical decomposition of H2O2 is autocatalytic and selfsustaining).Temp also produce more dissociation of the water and thus more OH- anions that are catalytic for the earlier process! Metal ions also does catalyse the decomposition (ever tried a single cristal of KMnO4 or MnO2 into a 1L H2O2 30%...O2 gone in a minute).

So keep cool and acidic!!!

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"Life that deadly disease sexually transmitted".
"Chemistry is all what stinks and explode; Physic is all what never works! ;-p :-) :o)"

[kingspaz]

this is off topic but is kind of relevent. leaking H2O2 sank the Kursk sub of the coast of norway. the H2O2 was used for oxygen supply for the torpedo engines. somebody started the engine before the torpedo was in the water which increased engine revs dramatically as there was little resistance compared to when in the water. anyway the end result was that H2O2 leaked contacting copper and brass internal parts of the torpedo. this inturn released oxygen which built up pressure in the torpedo hull eventaully resulting in an explosion. you can guess the rest. i saw it on a decumentary on BBc 2.

[Anthony]

I think this method of concentrating H2O2 by heating would take some trial and error to makes sure you didn't go to far and have whole lot decompose on you.

I saw that program too, the amazing bit is that the torpedo casing rupturing (essentially a pressure bottle explosion) was picked up by a seismology station in the UK - half way around the world! Makes me wonder if I ever produce any little spikes on their graphshttp://theforum.virtualave.net/ubb/smilies/smile.gif

[BrAiNFeVeR]

It's just that water makes an excellent shockwave carrier for long distances.
I once threw a large cracker of a dam somewhere in France (i was standing on the dam) and threw it as far as i could, and i swear, the entire thing was shacking!! Me and my nephew totally cracked up, and then left before someone came to make any trouble...
Please note that this was only a cracker that can be bought in any store, with a rock attached to it !


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[A-BOMB]

Brain? what does water shockwaves have to do with H2O2 concentrating?

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live by the bomb
die by the bomb

[VasiaPupkin]

Its not possible to make better concentration of H2O2 by cooling. Mixture will freeze all. In all kind of concentration... Info from book "Non organic chemistry" Vol. 2 by Novicov (translated to english) "Its possible to rise H2O2 concentration up to 30% by evaporation of 3%H2O2 medical solution in clear glass. In 60-70 C temperature. Yeild good -near 95%" My friend prepared H2O2 (I think it was near 30% concentration) from 3% H2O2. He simply poured out 3% H2O2 into flat open glass and cover by list of paper at room temperature (be sure in the dark) at 3 days. H2O2 solutions most stable in pH 3.5-4.5. One non detailed way to make H2O2 is "anode oxidation" (kind of electrolyse) of weak H2SO4 solutions: 1) 2H2SO4 -2e => H2S2O8 + 2H+ 2) H2S2O8 + H2O => H2SO5 + H2SO4 3) H2SO5 + H2O => H2O2 + H2SO4. It possible to prepare H2O2 with great and dangerous concentration. But it need a pure H2SO4 and coal electrodes... Can you buy a "hydropirite" tablets (solid CO(NH2)2.H2O2)in drugstore? Somethimes its useful to AP making. But I have bought 1 L of pure 50%H2O2. And have no problems now 8)

[BrAiNFeVeR]

That was a reply to a post that seems to be deleted ...


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"Mess with me, and you'll end up with a .44 under your chin and your brains on the ceiling"

[A-BOMB]

Ok thanx everyone put I dont have any chemicals anymore or apporatus because I fire in my lab and melted and burnt http://theforum.virtualave.net/ubb/smilies/frown.gif everything in there including the h2o2 (all 12 liters of it)I was going to concentrate it was a wierd fire in that the AP in the chared can had the rubber seal melted put the AP didn't go off and the strike-anywear matchs right next to it didn't light but the box ontop of it did and that something I had in there made all of my tools get rusted over in the day after even though not rusty the day before and firecraker right on the table didn't light but the tissu wrapper burned whats up with that and i'll put up a pic of the burn AP can. You got to see this!

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live by the bomb
die by the bomb

[This message has been edited by A-BOMB (edited September 17, 2001).]

[Tristin]

This guy makes 90% H202 http://www.tecaeromex.com/ingles/indexi.html

Check out the H202 distillation link.

[NoltaiR]

Ok, finally found the old thread on purifying H2O2!

Anyways I am currently boiling some 3% H2O2 at 105*C. If any of you new members have some comments on this method, please do.

[NoltaiR]

Well I stopped boiling mine once it was about 1/10th as everyone seems to agree on here. It is currently cooling for a few minutes in my freezer. The main thing I did notice is that over time, it required more and more heat to keep a steady boil, which could be proof of disturbed's statement about 3% boiling at 100, 30 boiling at 106, etc.

[Kalium]

You can make H202 more conc. by evapuration( Temperature should be 60`C )

[RTC]

<a href="http://theforum.has.it" target="_blank">http://theforum.has.it</a> - a zip file that has 5files on concentrating h2o2.

[A-BOMB]

Wow I forgot I even that I started this topic. And I've found a few things out after my fire is that I find that if you make AP with a very low concertation of hydrogen peroxide (like 1.5 percent thats what I'm using now) you get smaller crystals or what ever of AP and it burn/deflagrates faster and detonates better(well for me that is).

[NoltaiR]

1.5%? I get such a crappy product at 3% that its not worth the time. What kind of ratio would you use with 1.5?!?

[Anthony]

The standard 6:1 acetone:pure H2O2 ratio

[Rat Bastard]

I have 6%. Should I even bother to concentrate it?

[Anthony]

I wouldn't because you'll loose some H2O2 in the concentration process, giving you less AP or HMTD for what you spent on the 6%. Might be worth it if you want a more convinient to use concentration of H2O2 though.

[A-BOMB]

Any way the lower the percentage the longer for the reaction to take place meaning a reaction temp. Means smaller crystals of AP(or whatever) which means at least in my tests it burns/deflagrates faster than with 30% or even 6%.

[NoltaiR]

Well the AP that I am currently making (it is now in a shed sitting in a ice/salt bath) used the ratios given on mega's site of 50mL acetone: 30mL 30% H2O2: 3mL 75% H2SO4. Except that I am using 3% H2O2 that I boiled down. (Also I sized up the amount a little bit and I am using 150mL acetone: 90mL H2O2 : 8mL 91% H2SO4)

And boiling the H2O2 definetly affected the reaction time.. the last AP I made, I used 3%, just 10 times the given amount. And you are right about it making smaller crystals although I hardly think it is worth it because there wasn't much (if any) visible difference as far as brisance goes however it took 4 days to get a satisfiable amount (Which even then it worried me because much of it had evaporated leaving dry precipitate on the sides.. I can't believe it didn't detonate on its own because I was using H2SO4. But as soon as I was ready to remove them I just slowly filled the beaker the rest of the way with water then filtered it out.)

Anyways what I was saying about reaction time. The last AP I made, I added in the H2SO4 in a slow stream from the pipet and it barely broke 10*C from the original 4*C and even then it quickly returned to its original temp. This stuff I am making right now was made by adding the H2SO4 in just a medium-fast drip and when I only had half the acid in, it was steaming! (I wasn't paying attention to the thermometer, and when it started steaming I immediately quit adding the acid and checked the temp.. it had reached at least 27*C.. it only took about 10 minutes of adding a lot of ice to the ice bath to get the temp back down below 10*C but I hope this little accident won't effect my product much--if anything I expect it to probably have a bit more of the dimeric this time.. so I will have to be extra careful). After about 30 minutes of sitting it was down to 5*C and then I slowly added a mL at a time every 15 minutes to make sure I didn't heat it up again.

[NoltaiR]

And one more thing, the stuff I boiled down last night started at 1 quart (approx 950mL) and when it finished it was down to 90mL. It smelled much stronger than the 3% (obviously, although I shouldn't have smelled it). However while it was boiling I was reading that UV light breaks down the H2O2. Well this was at night and only a dim light was on.. will this affect it much? Also I read today that H2O2 normally decomposes slowly, however metal catalises (spelling?) it so it decomposes more so i am not sure if me boiling it in a galvenized steel pot hurt it very much.

[Pu239 Stuchtiger]

I'm not completely sure about this (pulling this info off of the top of my head) but I'm fairly sure that some phosphates are used to stabilize hydrogen peroxide solutions.

[VX]

No, the light will have made practicaly no difference what so ever to it's con. Even storing in daylight (not direct sun) only results in a fairly slow breakdown of the H2O2.

Anyway you say that is smells strong. I might be wrong but I thought that H202 had no smell... my 30% hasn't anyway.

[NoltaiR]

When I said it smelled strong, I meant compared to the 3% which doesn't have a noticeable smell (that I can detect). If it was compared to other smells in general, it was quite faint but I can't really describe it.

[NoltaiR]

And also some of you guys say not to purify it because some H2O2 will be lost. The problem with this is that when it is low then the reaction takes twice as long and there is more of a chance that your temp will rise above 10*C because the ice bath only stays cold so long before it has to be refilled. Well I guess if you put in a refrigerator that wouldn't matter.

Also H2O2 only costs about 80 cents a quart, so buying more is not a problem.

[kingspaz]

yup, phosphoric acid is used to stabilise the H2O2. well atleast it is in mine.
hmmmm.....galvanised steel. thats zinc plated isn't it?
i've not heard of zinc being used as a catalyst in other reactions so i'm tempted to beleive it would not significantly affect the H2O2. the only metals i know to catalyse its decomposition are copper, brass (i beleive due to the copper content not the zinc) and MnO2.
<img src="http://www.h2o2.com/intro/properties/pic10a.gif" alt="" />

thought this may be of some use.

<small>[ March 16, 2002, 06:28 PM: Message edited by: kingspaz ]</small>

[Anthony]

Well at $0.80/qrt I'm not surprised you don't care about losses, I day about quadruple that for 6%, so double for the same amount of actual H2O2. My peroxide reactions live in a small fridge.

[vulture]

Concentrated peroxide has a ozone smell. This is due to the fact that singular oxygen evolves from the solution. This is very reactive and tends to form ozone with atmospheric oxygen.

[NoltaiR]

I didn't think of that.. ozone is exactly what it smells like.

[vulture]

Would it be possible to concentrate H2O2 in the same way you concentrate HNO3, that is vacuum destillation?

The decomposition of H2O2 is auto-oxidized by radicals:
HOOH -> H + OOH or HOOH -> 2OH-
So stabilizing could be done with a pH buffer which absorbs the OH- and H+.

Other ways of preparing H2O2:
1.bariumperoxide + H2SO4
2. Electrolysis of peroxodisulfuric acid or ammoniumperoxodisulfate
this yields up to 35%-45%.
3. Here you can buy stain removing salt, which is sodiumpercarbonate.
When dissolved in water it yields H2O2. Usually it's mixed with something else, but if you can separate it you should get fairly concentrated H2O2.

[mr.evil]

i know you can make H2O2 yourself, by adding some diluted H2SO4 to Barium(or other heavy metal peroxides), there will settle down a salt and the H2O2 stays in the solution.(look above, Vulture has said this to)

i have heard that you can make H2O2 up to 45% with this method, has anyone tried this?

Cya

<small>[ March 25, 2002, 07:42 AM: Message edited by: mr.evil ]</small>

[Sparky]

As fate should have it Skylighter happens to be selling barium peroxide for a limited time. It can't be shipped though so you have to go pick it up or go to a conventionto pick it up :( . Would it be easier/possible to create barium peroxide from other barium salts and maybe H2O2 instead?

<small>[ May 05, 2002, 12:44 AM: Message edited by: Sparky ]</small>

[NoltaiR]

I am not sure what the trick is for those of you guys who claim to make AP with 3%. Normally I boil it but I decided to give it a try. the ratio was 1.9L of 3% H2O2:350mL acetone:30mL 94% H2SO4.. its already been 24 hours and no precipitate can be even seen.

[Energy84]

I'm no expert when it comes to AP as I've only made it once, but I did it with 3% H202, and 32% HCl. I don't remember offhand what the ratios were but it must have sat for 3 days before anything appeared. <img border="0" title="" alt="[Frown]" src="frown.gif" />

[kingspaz]

sparky, you can't make it from other barium salts because the acid of the salt will form:
Ba(NO3)2 + H2SO4 ---> BaSO4 + 2HNO3 (barium nitrate + sulhpuric acid ---> barium sulphate and nitric acid)
shit, brain freeze whats the formula for barium peroxide?...hmmm....
BaO2?
BaO2 + H2SO4 ---> BaSO4 + H2O2 :D ...looks like it is BaO2.

[mr.evil]

well i suggest you make some BaO2 yourself,
By adding some Bariumsalts to a NaOH solution. i've never tried this method, so i will expiriment a little, seems nice, making 45% H2O2 by adding some H2SO4 to BaO2 :) really cheap source!

Cya

[ThaFreak]

I can buy my H2O2 at 30% and it's really cheap.5$ for 600ml!
And It's true that when using a high concentration of H2O2, there wil form much larger chirstals then when using low concentrated H2O2.

[Jager]

Found it at <a href="http://webhome.idirect.com/~earlcp/FAQs/FAQ.html" target="_blank">http://webhome.idirect.com/~earlcp/FAQs/FAQ.html</a>

Can I concentrate H2O2 myself by Boiling it?
Yes! But don't do it! Three main reasons are:

(A) It is very dangerous! H2O2 fumes are very unhealthy to breathe, plus if the vapor concentration is high enough the vapor can act like an explosive. Finally the oxidation ability of H2O2 vapors could cause fires to start.

(B) As the temperature rises the rate of decomposing increases exponentially, at the same time releasing heat. At some point especially if there are any contaminates in the H2O2 to aid decomposition there could be a thermal run-away reaction resulting in an explosion or if milder you will get the H2O2 sprayed all over the place.

(C) Because H2O2 starts to decompose fast when heated you will lose a lot of the H2O2 to breakdown. You thus just turned a lot of your expensive H2O2 into water just because you decided to boil it.

Can I concentrate H2O2 myself by simple distilling?
No, not really. The problem is that the vapor pressure of water is generally 10 times greater than that of the H2O2, thus you end up distilling water not H2O2, the H2O2 is left behind in the evaporator. However, as pointed out in the boiling section above if you raise the temperature of a H2O2 solution you start decompose the H2O2, turning it into water. Simple distilling will tend to waste a lot of the H2O2 contents.

Can I concentrate the H2O2 myself by vacuum distilling out the water?
Yes, the first thing to realize is that vacuum distilling lowers the boiling point. Thus the evaporator can be operated down at 30 to 40 degrees Celsius and thus you get to remove the water without decomposing the H2O2 from thermal breakdown. I did find that maintaining a vacuum for a long time to be very difficult but not impossible. Second, any contaminates in the solution will be left there. This could make the H2O2 very dangerous if the wrong contaminates were there in the first place.

Can I purify the concentrated H2O2 myself by vacuum distilling out the H2O2?
Yes, as before you can lower the boiling point under a vacuum. Notice that H2O2 have a far higher boiling point than water so you need a harder vacuum which is more work. But it can be done. However, you now have hydrogen peroxide with no stabilizers in it, this MUST be kept in a very clean container for safety reasons.

Can I concentrate H2O2 myself by freezing?
Yes, you can, but there are has limits on how much water/H2O2 that can be removed by simple freezing. The problem is that at 62% H2O2/H2O solution the peroxide and water freeze together to form an H2O/H2O2 ice. Thus whether you are freezing a water rich solution or a hydrogen peroxide rich solution the remaining liquid tends to become a 62% solution where both substances blend and freeze together.

Can I concentrate H2O2 myself by freezing out the water?
Yes, you can, when H2O2 is a small percentage of the solution i.e. less than 40%, the ice that forms is mainly water, so that the percentage of H2O2 left in solution steadily increases as more ice forms. However, some of the H2O2 freezes in the ice also, so there is a loss that gets worse as the percentage of H2O2 approaches 62%. This is a useful and easy way to concentrate very weak H2O2 solutions however. Notice will this process really tends to leave any contaminates in the solution.

Can I concentrate H2O2 myself by freezing out the H2O2?
Yes, you can, but there are has limits on how much H2O2 can be removed by simple freezing. If you start with a 90% or higher H2O2/H2O solution the ice that forms is almost pure H2O2, however the same limits still apply. As you freeze more and more of the H2O2 the percentage of water in solution climbs, and so does the amount of water that freezes in the ice. Again, the freezing will balance at 62%.

[Celtick]

Hey ThaFreak:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">I can buy my H2O2 at 30% and it's really cheap.5$ for 600ml!
</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Contact me; I live in Hoogvliet so that’s around the corner! Since I only can get 3 or maybe 6% H2O2 maybe we can make a deal?

[inferno]

KNO3 + NaOH ==> KO2 + NaNO3 + H2
(s) (aq) (s) (s) (g)
(not balanced)

Then

KO2 + H2SO4 ==> H2O2 + KSO4

Thats possible. But how would u separate the KO2 from the NaNO3? IIRC potassium superoxide is orange, i guess that would help a bit.

This would be a very cheap source of H2O2. Just use a nitrate + sodium hydroxide (drain opener, sold as DRANO or much cheaper just as sodium hydroxide in supermarkets) then add the metal peroxide to sulfuric...and does it yield around 40%?

[andreas]

how would you let this react in a solution.
K2O + H2O --> K+ + 2OH-
I don't know how you are going to make this work?

[vulture]

That reaction will just yield KOH and NaNO3! KO2 is an endothermical compound, you can't just make it that simple. You have to heat metallic potassium in pure oxygen to get KO2.

[Polverone]

Actually, won't that reaction yield "nothing new?" I mean, with ions zipping around in solution there may be an equilibrium with some KOH/NaNO3 present, but for the most part you're going to have what you started with - KNO3 and NaOH, since K is more electropositive.

BaO2 can be formed simply by heating barium hydroxide or oxide to a few hundred degrees C in open air. The trouble is getting the barium hydroxide/oxide in the first place. Barium is chemically similar to calcium, and you can obtain BaO from BaCO3 simply by heating the carbonate in open air (just like with calcium carbonate). But the temperature required is very high. Or you can react BaCO3 with HCl to obtain BaCl2. The BaCl2 is soluble and could be electrolyzed in a cell with a semi-permeable membrane to obtain Ba(OH)2. Or you could react the BaCl2 with KOH to obtain KCl and Ba(OH)2. The barium hydroxide isn't as soluble as KCl, so it shouldn't be too difficult to separate.

Unfortunately, I cannot recall how hot barium hydroxide must be heated before it becomes oxide. It may be that you're back to the first problem of creating really high temperatures.

Or - the *really* roundabout way - electrolyze a molten barium salt to obtain the metal, burn the metal in air to obtain the oxide. This is hazardous and indirect but the barium itself could also be fun. This shouldn't be as difficult as obtaining sodium or potassium since barium is dense enough to sink below its molten salts, protecting it from oxygen.

All my routes start from BaCO3 since it is easily and cheaply obtained as a pottery glaze material.

[andreas]

Yes I think you're right it wouldn't yeild nothing new

[vulture]

Wondering: would ozone oxidize water to hydrogen peroxide?

[kingspaz]

hmmm....it may not do it alone but is its decomposition was catalyised in some way then i don't see why it wouldn't work.
O3 --catalyst of some sort---> O2 + O'
O' + H2O ---> H2O2
O' = oxygen radical.
dunno what causes its breakdown into O2 and a radical. UV light does but that also decomposes H2O2. doesn't ozone decompose by itself anyways?

[vulture]

Well, ozone seems to be soluble in water, so no reaction to H2O2 i'm afraid.

The formation and decomposition of ozone is dependant of the wavelenght, one wavelenght will create it, the other will decompose it.

Ozone has a somewhat small decay time, but one can store it for 83h in 20N NaOH solution.

The idea about the oxygen radical could work though. I think it's a bit tricky cause you've got to end up with O2 with a charge of 2-, meaning oxygen has oxydation state -1 here. Seems pretty tricky to me.

[kingspaz]

vulture, i'm confused as to what you are saying.
the 3rd oxygen atom is dative bonded to the lone a lone pair on the O2 molecule so upon decompostion you end up with an oxygen molecule and an oxygen atom with 2 unpaired electrons. the radical would then attack the water forming H2O2...i think...in the O2 molceule oxidation state is 0 and on the radical its also 0.
i think the problem with this idea is finding the wavelength that will decompose O3 but not H2O2.

[vulture]

I meant the oxidation state of O2 in H2O2. It's the only compound where oxygen has a -1 oxidation state.

[Zambosan]

Vulture, just a sanity check (on my part): this is the only compound where oxygen has a -1 ionization state. Why wouldn't this be the case in other peroxides?

[vulture]

I was getting ahead of myself there...
In redox calculations, you have to assume oxygen has an oxidation state of -1, which you'll see if you try the sum of the oxidation states.
I don't know if this is also the case in other peroxides, especially where carbon atoms are involved. I would have to figure this out with structural drawings and accounting polarisation.

What I was trying to point out is that simply adding another oxygen molecule doesn't always creates a peroxide.
One could easily assume that PbO2 is a peroxide because BaO2 is.
This is false however, because it does not contain a -O-O- bond but
O=Pb=O. See where I'm getting at?

[spydamonkee]

i recently aquired some 50% H202 from a "friend" and he says its really old so might not be as pure as it was before.

does this stuff decompose or something in long storage or will my batch still be near 50%?

[kingspaz]

yes H2O2 does decompose gradually in storage. if it hasn't been exposed to direct light or high temperatures very often then it should be reasonably ok. unless its more than 10yrs old or anything.

[FlaAlchemist]

Pure conc H2O2 is made in the laboratory via the barium peroxide route.;)

[phoenix945]

Would it be possible to store H2O2 frozen in a freezer and it would not decompose as quickly?

[Boomer]

It would surely slow down decomposition, like with fuming nitric etc.

But actually freezing it needs below -50 C for a 50% solution. This is why I do not believe some noobs claiming to concentrate 3% to ten times+ the concentration by freezing out the water.

On the other hand, the near 100% stuff freezes near zero again. The curve looks like a deep valley.

[Harpoon]

Copper oxide acts as a weak catalyst for the decomposition of H2O2. Silver also catalyses the decomposition, and was used in rockets. All the other catalysts I can think of have already been mentioned.

The data book I was looking at said that H2O2 boils at 50 oC and freezes at 0 oC

Evaporating the H2O2 and then condensing it to acquire a higher concentration of H2O2 would allow it to be frozen and then separated from the water.

[Marvin]

Boomer, Harpoon,

The data you are discussing is at the top of the page!

30% peroxide freezes at -25C, given you lose some peroxide in the frozen water its quite possible you could reduce volume to 1/10th in a deep freeze.

Harpoon,

H2O2 boils at about 150C, not 50C. You can concentrate by gentle boiling but decomposition tends to prevent you getting to higher than about 40% at atmospheric pressure. A Eutectic occurs in the solid phase between 50 and 60%, so getting higher than this is not feasable by freezing, even if the temperatures can be reached. Leaving 40% in a vacuum dessicator over sulphuric acid can concentrate indefintly 90%+, though loss of H2O2 is probably sizable.

[Mendeleev]

One way of purifying hydrogen peroxide, I have not seen mentioned on this thread, is sparging. Sparging is bubbling warm air through a solution, causing the liquid with the lower boiling point to evaporate first. Its basically just like boiling off water, but safer. I am not sure how high you can concentrate hydrogen peroxide with this method.

[Cyclo_Knight]

Just so you know...Buying pre-concentrated 30% H2O2 is much cheaper than concentrating 3%.

Any well stocked pool supply store sells 27% H2O2 as a "Shock Treatment and Oxidizer". I bought a freakin GALLON of it for only US$20.00 under the brand name "Baquacil".

Unless you live under the sea, chances are that many people in your country own pools. Just grab the YellowPages, or an equivelant and start calling all the pool stores in your area. After the fourth call, I found a supplier only 15 minutes away.

400 ml of 3% runs me $1, and considering that much is lost in heating, I saved shitloads of money. I estimate that concentrating the same amount would cost me TRIPLE what I paid for Baquacil. A gallon of 27% H2O2 for 23 bucks including gas? I'll take it!!

[SimplisticNick]

Tomorrow I plan on going to the local pool shops.
My experiment of the moment is as follows;
My air cleaner produces ozone as it cleans the air (a lot, the company claims). I'm taking apart and making it into an airtight seal in which i can bubble O3 through 3% H2O2. Hopefully, the concentration will rise.

[FUTI]

the "freezing method" is very interesting...at least to me...this is the first time I ever find someone mentioned it. Can you point this blind samurai where to look?:) A book, name of the author, anything will be usefull but proven sources have the slight advantage over kewl links. Thanks.

EDIT:
I'm aware of the fact that freezing some water solution you can obtain separation (at least partial) of components. Examples are freezing of sea water which makes ice with less salt then original solution and remaining solution has higher salt concentration, or methane water clathrate forming as solid residue in cold water under pressure. But the formation of eutectic mixture mentioned here is interesting to me...let me guess it lay somewhere around 56% H2O2?

[SimplisticNick]

Well, no more need for concentration. I have found 35% conc. at my local pool store.
1 gallon for about, $13.89. Well worth it!
The freezing method does work extremely well, but I could not get the exact concentration of the H2O2, for my KMnO4 stock is low. I let a full 900mL of 12% H2O2 (from beauty supply) freeze over night. In the morning, I cracked the ice open and dripped out what didn't freeze (very conc. H2O2).

[Marvin]

SimplisticNick,

Ozone destroys hydrogen peroxide.

FUTI,

Its a very common method in general chemistry, you are unlikley to find any instructions in a modern journal or book specifically for hydrogen peroxide. Its mainly a mtter of interpreting phase diagrams. More than enough information is referenced in the thread to give it a try.

[megalomania]

I have been reading up on the Shell Process of making hydrogen peroxide, which uses isopropyl alcohol and air. The alcohol is oxidized to acetone and hydrogen peroxide. The process can also use methyl alcohol, making formaldehyde and peroxide. I have not read the patents yet, except the first one. They are US 2479111, US 2871104, GB 708339, BE 1002295

The formation of formaldehyde is what grabbed my attention, although there seems to be some complexity using primary alcohols since they do not do it industrially. Only secondary alcohols are used.

According to the first patent excess air and alcohol vapors are passed through a tube heated to around 400-450 C and quickly condensed and passed into water. No catalyst, no exotic materials, no special labware. The reaction time is about 30 seconds, so a long tube is required. With isopropyl alcohol you end up with a mixture of hydrogen peroxide, unreacted alcohol, acetone, and water. The works are gently distilled under low pressure to get the alcohol, water, and acetone back which are recycled, and hydrogen peroxide is eventually concentrated.

Supposedly the modern version incorporates between 1-3% hydrogen peroxide to kick start the reaction. Hydrogen peroxide is the catalyst in the reaction, it is self catalyzing. Adding initial hydrogen peroxide improves the yield.

If I had to design a system to do this I would probably make a long pipe (36") from concrete or mortar by coating a dowel rod. I would get a bit of duct work or sheet metal and make a simple box in which to cover the pipe with charcoal briquettes (like a grill). I would affix a Y tube to the beginning of the tube and connect one side to a boiler and the other to an air compressor. You can use either methyl, ethyl, or isopropyl alcohol diluted with as much water as you want. 75% right off the shelf is about average. Add a bit of peroxide to the alcohol to help the reaction. A small air compressor blowing at low provides the air in the other end of the Y fitting. The exit end of the tube can be bubbled directly into ice water.

Yields may vary, the patent says over 80%, but any unreacted alcohol can be recovered and used again. This method sounds like a good way for making formaldehyde; a double bonus perhaps?

Mayhaps using this process for AP would not even require purification. Just add the acid of your choice to form AP, filter to remove the crystals, and distill the alcohol from the remaining liquid. I wonder how economical this would be vs. buying acetone and peroxide separately?

[hereno]

The process can also use methyl alcohol, making formaldehyde and peroxide.


Isn't that a bit dangerous? Formaldehyde and H2O2 react to form dimethylolperoxide, you really would not want to distill this mixture, check here for an attempt to isolate it:

http://www.sciencemadness.org/talk/viewthread.php?tid=2574

I guess you could use this process to form HMTD and AP in situ :p

[megalomania]

Ahh, so maybe that's why they don't do this industrially with primary alcohols... The resulting aldehydes are just too easy to oxidize further.

[boilingleadbath]

There doesn't seem to be very much H2O2 lost during boiling. Although the evidence is weak, my most recent synth of TCAP indicates that less than 10% of the H2O2 is lost:

110 ml of 3% H2O2 where boiled down, vigorous boil, in an aluminum pot to ~10 ml. This was mixed with 15.0 ml acetone, and 6 ml 31% HCl - 10% extra H2O2. Reaction was successfully preformed at low temperature and then allowed to react at 5*C for 19. hours, capped.

In an attempt - which now seems like a bad idea - to remove any excess H2O2, a small amount of MnO2 was added to the product still in the reaction vessel, pre neutralization. A small amount of fizzing was observed, which I assume indicates an excess of H2O2... although I'm suspicious of a reaction with the HCl [also], as the filter water was a reddish-brown color.

[corrosive]

Sorry to put anyone's shit down but theoretically concentrating H2O2 isn't neccesary, (as I've read). Primarily in peroxide compounds the, reaction still happens you just have to wait a bit longer. Also I do not want to take this off of topic, but can anyone tell me quickly if it is neccesary in peroxie compounds such as, hexamethylene triperoxide diamine, triacetone triperoxide, and methyl ethyl ketone peroxide to have a more concentrated oxygen such as 6% minimum. I would just like to know this for further "dreams". At the moment I have plenty of the 3% and I would like to have a personal reply if it is really necessary. thanks.

It would'nt hurt to get "Shock Treatment and Oxidizer" for less liquid, so I can use smaller containers and use an ice-bath efficiently.

[Chris The Great]

In theory. I've never had a decent yield at all with 3%, but with 35% I get so much AP is turns into a solid mass. I get far more once it has been filtered and dried. It does make quite a difference in practice.

The equilibrium of the precursors tends to stick to the water soluble ones, and not go all the way to completetion, when you have more water in the reaction mixture, at least with AP.

[Chopper]

In any event, the rate of reaction is not going to vary linearly with the conc of the H2O2.
The rate of reaction would have a relationship that is somewhat logarithmic in nature.

I.e at a reagent strength of 1/10, I would expect (though have never tried) that
the time needed for the reaction would increase 100 fold - and not just 10 fold.
Adding to this, of course, is the fact that the equilibrium point will be shifted somewhat.
How much? Once again research I've not carried out.

However, by the addition of a small amount i.e 1ml phosphoric (800gm/liter soln)
to 200ml of 3% peroxide, the loss due to decomposition may be vastly reduced.
This was my standard method until my phosphoric ran out. At this point I went
to get some Ph Down from a hydroponics shop, since my preffered brand of
rust-converter was unavailable.

It was here that I came across 500ml (600gm) of 50% H2O2 for $13. Considering
I'd been previously paying $3.50 for 200ml of 3%, It takes no einstein to work
out that the hydro-shop route is much, much cheaper and easier. I.e 300gm H2O2
for $13, as opposed to 24gm H2O2 for $16

Especially when you consider that they also supply 5L drums of 50% for around
$80. Which is still rather expensive!! (They probably pay around $30 for same)

[akinrog]

I really wonder something.
I saw recently an international marketing network called *mw*y is selling a bleaching product containing Sodium Percarbonate (30 % - but it does not state whether or not the rate is in Weight or Volume).

Can it be used for something useful? I mean is it possible to extract hydrogen peroxide therefrom? Regards

[nbk2000]

It's been discussed before, and the answer was 'Yes, but at far greater cost than 3% peroxide, so why bother?'.

Search for oxyclean or oxy-clean. Percarbonate might also work.

[The_Duke]

Percarbonate might also work.

Having used Percarbonates as a source of H2O2 on several occasions I can assure you that Sodium Percarbonate will work as it releases Hydrogen Peroxide and Sodium Carbonate when dissolved in water, the H2O2 will react with the Acetone and the Sodium Carbonate will react with the mineral acid to form the respective salt.

[nbk2000]

And the mineral acid, being the catalyst, is converted into useless salt by the carbonate formed by the decomposed percarbonate.

So then you're reaction is a competition between catalyst-reaction, and salt-formation.

[Chopper]

Of course the formation of salt would use some of your acid. In this case, it is a rather trivial task to calculate the amount consumed in the formation of the salt, and simply add the corresponding amount extra.

Said salt would remain soluble and could simply be washed out with the rest of the liquid remaining after the reaction.

That is, of course, unless I'm missing something here particular to percarbonate.

[NoltaiR]

Seriously guys. I am assuming that the only reason you want to "refine" your store-bought H2O2 is for use with AP. If not then continue. But if you are just trying to make it stronger for AP production then just boil it!!! I really don't get why people try to get so technical with the addition of other chemicals..

[aikon]

...But if you are just trying to make it stronger for AP production then just boil it!!! ...

I didn't check the whole site, so I can't say anything about it's quality but here's a link where a guy boils down 3% hdrogen peroxide. Look in the "Scientific Crap" section.

http://www.experi-mental.org/

[nbk2000]

There's a name there from the deepest bowels of BFL...THErAPIST!

Holy shit...THErAPIST is buddies with the K3wL who owns that site. :rolleyes:

That explains the 'quality' information to be found there. :p

[NoltaiR]

I sincerely hope you are in no way referring to my reply as crap. This is the method I have used everytime I needed a stronger H2O2. It has worked everytime and I have provided proof with photos in the past. Please do not try to demean/disgrace me. I have been in the business for quite a while.

[aikon]

@NoltaiR

I agree with you, that boiling the H2O2 is the best way to concentrate it.
It's simple and you'll obtain a strength good enough for most applications.
NBK didn't say anything against your method, he has just a litte dejavu when he hears the name "THErAPIST". That's all. :)

[nbk2000]

Aikon, I don't think he was referring to me, but rather you..."Scientific Crap" .

[NoltaiR]

I was referring to your reply Aikon.. you honestly think I would ever question NBKs replies.. ;)

[aikon]

I was referring to your reply Aikon.. you honestly think I would ever question NBKs replies.. ;)

Ups.
A little misunderstanding.
You're right, never ever question the master himself. :D

[kleptophobiac]

Leslie's Pool and Spa, a pool supply chain in the US, carries gallon jugs of 27% hydrogen peroxide as a pool clarifier. Go to your local pool supply place and look for any bottles sold in plastic bags (same technique when looking for H2SO4) One gallon is $16. Some other pool places (they seem to be local, however) carry up to 35% for nearly the same price on a 100% basis. You'll also find all the sodium hypochlorite you'll ever need at one of those places.

Before I found the pool and spa place, I concentrated hydrogen peroxide from the 3% variety because I needed an etchant for circuit boards. 3% was just too darn slow to be useful. I took a large corning baking dish and put it on high heat on the oven. I could get up to about 20-22% with the method. I prefer the corning because it's about the most unreactive vessel you'll find, isn't porous, and has a very large surface area.

The freezing method just sucked for me. The water would freeze into crystal shards and would become a slurry in the bottle. I couldn't get much of the high(er) concentration H2O2 before a lot of the crystals melted, nullifying my efforts.

Of course, finding the 27% stuff basically made the effort a waste of time. It etches so fast the solution gets very hot, whereas before I had to heat the solution to increase the speed of reaction. Fantastic!

[Abnormalia]

I would definitely vote for the vacuum pumped distillation as the best method (outside of the warm air bubble method, which I am not familiar with). A vacuum pump will be the hardest part to find, maybe a science surplus store.

Placing the 3% H2O2 in a container for vacuum pumping (some kind of vacuum flask) and place that into a container of warm water. During the vacuum process, the liquid will cool due to the vaporization of the water, which will lead to a slow evaporation rate (again, the warm water helps to keep the flask at a neutral temperature and vaporization going).

This should work well, although I can't give you any concentrations to go on.

I was, at one time, interested in the H2O2 mono propellant rocket engines that NASA had experimented with.

The German's V2 rockets (to my knowledge) were fueled with "High test" H202. The H2O2 was pumped into the ignition chamber, along with a concentrated solution of KMnO4, which immediatley ignited producing steam and oxygen (deisel was added in later engines to take advantage of the extra oxygen generated). Anyways, just a little trivia - I don't suggest getting the H2O2 near any KMnO4 is what I'm saying.

Good luck!

[Bert]

Abnormalia-
The V-2 was propelled by 3800 kg of alcohol (ethanol and water) fuel, and the oxidizer was 4900 kg of liquid oxygen. The fuel and oxidizer pumps were steam turbines, and the steam was produced by concentrated hydrogen peroxide with potassium permanganate catalyst.

from Wikipedia http://en.wikipedia.org/wiki/V2_rocket

[PlayDough]

There is a method of concentrating H2O2 "well above 85%" which has not yet been mentioned in this thread, and I am convinced it is the safest and the most feasible for the home experimenter.

I ran across this patent for the process of concentrating H2O2 without the need for freezing, distillation, reagents, or catalysts. The patent is US7122166.

Basically, the dilute peroxide solution is passed along a water-permeable membrane made of a special material with a hygroscopic gas such as air on the other side of the membrane to carry the water away. Happily, DuPont invented just such a material they call Nafion which comes in an assortment of sizes and shapes of sheets and tubing.

I've been looking around for some Nafion tubing to build a little home version similar to the device described in the patent. Basically it would work like a swamp cooler. Peroxide solution would be circulated from a reservoir through a "radiator" fashioned from a network of Nafion tubing, then a fan would blow the water away in the form of humidified air.

I'm not sure exactly if pressure or a gas other than air will be needed to produce concentrations high enough to make rocket fuel, but I hope to make concentrations of at least 85% as mentioned in the patent, with no degradation of the H2O2 from heat or light.

+++++++++

Patent URLs expire, so post the number and country of orgin instead. NBK

[wymanthescienceman]

When I tried making AP with regular 3% peroxide from the store it just wasn't cutting it. I made it keeping the temp at about 5C and used HCl for acid. When I did it I used roughly 600-700ml of 3% peroxide and the correct ratios of Acetone/Acid but after a week I couldn't see any more precipitation and my final dry yield was <1g. As I can only get 3% around here, I decided to experiment.

SO failing my previous synthesis I tried concentrating my H2O2. I put 473ml (A 16oz bottle) in a temp controlled pan at roughtly 80C and let it evaporate for a couple hours until it reached about 60ml. Using the same methods and about 40ml of this concentrated H2O2 I was able to reach a yield of roughly 8-10g :eek: (I couldn't help but test it before it was completely dry so I don't know final yield :D) within 12 hrs of precipitation. I will do more tests to see what exactly the yield would be from a full bottle, but I'm guessing it will max at 12g. That is plenty for me, I don't use hardly any......yet :D .

I will come up with an exact method I use soon, noting temp at which it is evaporated, final volume of H2O2, length of precipitation, yields of AP, ETC ETC, after I use up what I have now.

[sparkchaser]

I was thinking of using a dessicant in a sealed container, with H2O2 (3%) which is still in the original bottle sitting on top. Dessicant would be calcium chloride. Can anybody think of a reason this wouldn't work at room temp.?

Another thing I'm worried about is any reaction from possible H2O2 vapor that might make it out of the bottle. Any comments?

Scratch that. Found my answer.

Yes, it would work because H2O2 is less volatile than H2O but don't ever pass its solution through the dry CaCl2 or MgSO4!!!
I hope you will dessicate it in a big closed vessel at ambiant temp (20C-35C) within what there will be another vessel containing the dessicant!Don't forget to add some sulfuric acid in the H2O2 to stabilise it when higher in concentration.
Always remember that H2O2 and metalic ions are not good friends at all; CaCl2 and MgSO4 contains such ions!!!!They can bring your batch to zero contain oxygen in very little time if brought into contact!!!!

[Altroman]

How about molecular sieve? That should be nearly pure silica gel, and as such should not catalyze the H2O2, yet should remove at least some of the water. It can also be regenerated easily in a hot, dry oven.

[sparkchaser]

I thought silica gel contained a small amount of either aluminum or zinc oxide. Am I mistaken?

[FUTI]

Drying silica-gel isn't pure, it is often "spiced" with cobalt salts as water indicator. Molecular sieve isn't silica-gel AFAIK. H2O2 can be decomposed even by catalytic influence of ordinary dust particle surface last time I looked. Are you guys find some new info I'm unaware of or just brainstorming?

[crsk8andsno56]

I have heated my H2O2 fairly fast before and have gone from 473ml to about 47 ml so should be around the 30% range.

I heated this fast, the flame was on medium and there was quite a bit of fumes/steam. I used this for a synth and got pretty go results with a yield higher than if i had used the 473 ml 3%.

I think I'm loosing some in the water or something I am not quite sure.

[lemons]

In addition to pool supply stores, a lot of health food stores and co-ops sell 35% H2O2. In addition to soaking veggies and such with it, some health food types dilute it and drink it. I pay around $8 a quart locally.

This co-op sells 35%, in sizes up to 55 gallon drums:
http://www.azurestandard.com/products/index.php?search=1&txtKeyWords=peroxide&x=0&y=0

[panzerkampfwagen]

Phosphorous Pentoxide could also be used as a dessicant, as long as you make sure that it is relatively pure. Purity is really only an issue if you are using the phosphorous pentoxide produced by burning matches. I tried using burnt matches and something in the match started boiling the water. It also appeared to be giving off gas, and not the kind that you would want to breathe in, either.

[Jabir ibn Hayyan]

I am not absolutely certain if this will work, but it has always been of curiosity to me, and I hope it will provide some help for all of you out there who want good old concentration without decomposition, so here it goes.

I believe the reason that your solution didn’t work panzerkampfwagen is because matches contain absolutley 0% red phosphorus, rather they contain a mixture of antimony(III) sulfide and potassium chlorate. Phosphorus Pentoxide can be obtained by heating red Phosphorus from the STRIKING PADS of matches, until it decomposes. Notice that the striking surface of a match box also contains powdered glass this must be extracted before you begin heating the phosphorus.

The result is such a powerful dehydrating agent that it can convert some mineral acids to their pure simple anhydrides. It has been used numerous times in the past to concentrate sulfuric acid without decomposing the precious Sulfur Trioxide within.

This bit of information is directly from Wikipedia:


The desiccating power of P4O10 is strong enough to convert many mineral acids to their anhydrides. Examples: HNO3 is converted to N2O5; H2SO4 is converted to SO3; HClO4 is converted to Cl2O7.


Hopefully phosphorus pentoxide can do the same for H2O2,and possibly help you guys with your concentration goals. The Pentoxide can also be used to make very powerful sulfuric acid which can also help concentrate hydrogen peroxide. Thank you, I hope this helps.

[DONMAN]

About the membrane idea... I have found OTC tubing perfect for such a task! Dialysis tubing is a water permeable membrane. I am doing a test with it right now and its only been a day but, half of the original volume of H2O2 is already gone!! I just tied both ends shut and hung it! Medical supply stores have this stuff and its super cheap!!!

[nbk2000]

Is OCT a name-brand, or did you mean OTC (Over The Counter)?

From what I've read, the membrane has good resistance to 30% peroxide, so that's excellent.

[DONMAN]

lol sorry my bad, bit of a type-o there. So far I have had my 47~ ml in some tubing for about 2 days now. Only 1/3 of the volume remains.

The only problem with the tubing is that when the membrane doesn't have liquid touching it, it becomes very brittle and can break very easily. I went to feel my tubing and the top part supported and tied with a rubber band just broke. Fortunately, There was no spill and I was able to retie it.

http://www.serva.de/products/knowledge/011002.shtml

Yes, it can stand hydrogen peroxide up to 30%. Also It says it can handle being frozen so I wonder if freezing 3% in a bag could be more effective for the freezing out method.

[AWG]

Ezikiel,
to make rocket fuel you need at least 90%. To this H2O2 you add a catylist(Silver is best). This then makes water(H2O) and Oxygen(O). There is also alot of heat which turns the water to steam. This steam can be put through a nozzle and drive a rocket. This technique was somethimes used in the V2 rockets. They also put kereose in the mixture which the steam ignites .
AWG

[kelb]

Ezikiel,
to make rocket fuel you need at least 90%. To this H2O2 you add a catylist(Silver is best). This then makes water(H2O) and Oxygen(O). There is also alot of heat which turns the water to steam. This steam can be put through a nozzle and drive a rocket. This technique was somethimes used in the V2 rockets. They also put kereose in the mixture which the steam ignites .
AWG

Humm thats interesting. How does steam with a theoretical maximum temperature of 100 deg C could ignite Kerosene (i'm assuming a typo here on your part) with an autoignition point of 220 deg C? Also since there would be a large amount of water vapor (aka steam) wouldn't that just put it back out? The V2 rocket propulsion system consisted of water alcohol mixture, liquid oxygen, and hydrogen peroxide but no mention of Kerosene in any of my information.

So is there any final verdict on the best way to go from say 3% to 30% H202 concentrations, given that you can easily, discretely, and cheaply obtain the 3%, and you don't possess a vacuum distiller? More importantly how the heck would you measure it to know when you got more concentration? Should higher concentrations be stored in better containers, say glass instead of plastic?

[megalomania]

If you get something hot enough it will burn, including water believe it or not. A water leak into a vat of molten steel will decompose into hydrogen and oxygen over 1000-1200 C, and it will explode with a force equal to TNT on a 1:1 ratio of the mass of water to TNT...

Water does not have a "theoretical maximum temperature" as you describe it, except for its decomposition temperature I just mentioned. Apply enough heat energy to water and its vapor can be heated far beyond what you seem to be confusing as the boiling point at the standard state. Steam under pressure, as one might expect in a rocket nozzle will allow water to be heated far above 100 C. It would not even require all that much pressure to reach 220 C. Engineering tables on the pressure-temperature relationship in boilers can be found via google.

There is no cheap, simple, and easy means of concentrating hydrogen peroxide without some kind of equipment. If there was, industry would use it. You can concentrate it a bit with staggering losses using minimal equipment, or you can actually get yourself some real glassware. The investment is well worth it.

As for storing hydrogen peroxide, what do you mean by higher concentrations? How how exactly depends on the material of choice. I can't recall from memory what materials are used for concentrations above 40%, but I know plastic is used at this, and all lower, concentrations.

Here is an interesting experiment to try concentrating hydrogen peroxide... Ideally you would want some NAFION tubing, but I gather it is somewhat expensive (about $150 a meter, but I am not positive on that, I will need to track down a better supplier), so dialysis tubing is certainly cheaper.

We are going to build a device rather like a condenser. A coil of tubing is immersed in a container, like a bucket, of hydrogen peroxide. Don't coil the tube tightly, but allow it to be completely wetted by liquid. Have both ends of the tube sticking out of the liquid, or better still stick a length of plastic or glass into the tubing to keep the ends wetted. Using a low pressure air pump, like a fish aerator or cheapo tire pump, blow a constant stream of air through the tubing. Air goes in, wet air comes out.

As the water permeates the tubing the interior becomes filled with moist air. The wet air is continually exhausted allowing more water to permeate through the membrane. The bucket of peroxide steadily becomes more concentrated over time.

I know NAFION will only let water through, but I can't vouch for how well dialysis tubing might work, or how long it will last in constant contact with highly concentrated peroxide. I also can't specify how high the concentration can get, but NAFION should be capable of producing 85% peroxide. How many days that takes depends on how much tubing (surface area of membrane) you use, how much peroxide you have, and what the starting concentration is.

[Alexires]

Mega - Would it be possible to use the same idea of concentrating H2O2 using NAFION to concentrate HNO3?

If so, I wouldn't mind blowing $150 on a metre of NAFION to be able to concentrate things like that.

Also, it might be possible to use dialysis tubing or NAFION to separate NaClO3 or KClO3 as it forms in a chlorate cell, as I understand that dialysis tubing lets salts through as well as water.

[Charles Owlen Picket]

If your are willing to spend $150 then you can get yourself a nice little 1L distillation rig and concentrate HNO3 to your heart's content! -{google Ace Glass}-

[nbk2000]

A $30 distillation flask with a telfon-tape wrapped stopper would be more than adequate.

Use a homemade condenser that'll cost you less than $10, and you're all set. :)

[megalomania]

Technically a distillation could be unsafe if the concentration of hydrogen peroxide gets to high levels and the glassware is not excessively clean. The presence of heat also leads to decomposition, and increases the risk. Using something like NAFION requires no energy (or very little if you blow air through it), and can be done at low temperatures.

NAFION is certainly harder to get and more expensive compared to glassware. According to the one website I found that sold NAFION tubing, they are the only company licensed to make NAFION tubing. Once the patent protection runs out, and other companies start cranking out NAFION products, the price of the stuff will plummet. I fully expect the prices to be 1/10th or even 1/100th of what they are now over the next several years.

One does not need a meter of tubing either. With all the fuel cells out there using NAFION membranes, these are easier to get. A divided cell with a NAFION membrane in the middle only a few square inches would be far less than any glassware setup and could continually concentrate hydrogen peroxide. Your yields would be very low per day, but if you have time this would be an excellent maintenance free concentrator.