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How to purify or concentrate Hydrogen Peroxide H2O2 over 3%?

10 Answers
Hydrogen Peroxide decomposes if you look at it the wrong way! So how can a 3% solution be concentrated to a higher strength solution? There are no less than three possible answers, I assure you.
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Thanks for the replies! Sandsc39 answer is the basic idea behind one method that will work, but the substance is so unstable to so many "things" that decomposition occurs far to fast to preform it quite that simply. The devil is truly in the details with these types of procedures. For instance, H2O2 decomposes under normal conditions. So an slightly opened bottle at room temperature will leave you with water after some time (?probably in a week I would think?)

Then to heat it you would be pouring it into, say, a beaker. Light greatly accelerates the breakdown to oxygen and water. In addition, assuming the beaker is not brand new, any traces of previous stains or chemicals substances of very small size increase the rate even more. The faster the temperature is raised the quicker it tends to react, and the decomposition is exothermic feeding further decomp with ever bit of heat released! To raise the temperature slowly, allows longer exposure to light and dust particles that reach the surface are enough to increase the reaction faster!

With all this working against you, the heating must be done very slowly and since pure water boils at 100C and pure H2O2 at 150C the temperature gap seems to be easy to separate, but the solution is so very dilute (your basically paying for 97% water!) that the temperature actually needs to be raised over several hours to right about 106C-106.5C to allow the water s vapor pressure to almost equal room temperature and start to mist. The use of a clean fan or compressor that will not introduce dust particles is very helpful due to the difference in vapor pressures of H2O and H2O2. If all these conditions are met the water will turn to vapor and escape the beaker from the fan which in turn raises the pressure and allows more mist to be produced, constantly. 1L of 3% will take about 4-5 hours like this and if done just right, I have produced up to 36% H2O2. It's not economical to say the least, but the theory is solid.

That is one of the three methods I've found to work, despite no one believing it is possible.


As to the heating of H2O2, it is safe at lower concentrations (probably below 50%), at some point the concentration is high enough that heating it decomposes so rapidly that it literally explodes into oxygen and water VAPOR which expands from the liquid phase to the gas phase so fast it can burn your flesh!

The Freezing method that was mentioned by Foreve99 Is pretty hard to produce anything much more useful than maybe 4% H2O2, in my experience. Although a similar method exists that is much more reliable, just has a few more steps, than the simple pop it in the freezer and catch the first 5-10 drops method. See if someone else can get the "cold" method I was just eluding to, or the third and most reliable method....

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Your right Foreve99 although under your post, the AdChoices advertisement on the top line nearly touching your words is the blue link label: "35% Food Grade Peroxide", with the text: "35% Food Grade Hydrogen Peroxide Our Discount Page - Since 1983". And the procedure I was speaking of at ideal conditions reaches right about that area of strength.

People use this concentration range of H2O2 for hydroponics, since it is believed by some to give additional oxygen to the roots as it waters them. It is also sold at 30-40% for health-obsessed individuals who use it for various "energizing" baths and other unusual things (such as very low level IV injection! Now that is just sounds plain ridiculous to me!)

But as far as my own work, I appreciate the thought, but I don't do anything that Is illegal, I don't have any type of chemicals that are even considered precursors to such things, nor any type of pyrotechnics, I merely use things that can be bought at common stores, never chemical supply companies even, and they could look all they want, I would be able to hand them a current MSDS binder to save them time.

I'm about two thirds done working on a book based on home or amateur chemistry at present, and that is why I only buy what anyone can have access to. I'm simply not comfortable with CHEMISTRY being a bad word, as a response to the actions of terrorists and drug labs. There are no chemistry sets anymore like everyone had when I was younger. What is there to allow the next generation to get inspiration from? Textbooks? Lectures? Pop-quizzes? I think that the effect would be quite the opposite.

Regardless, I can see that this thread is going nowhere, slow!

And I don't think anyone is going to answer after reading all the chat. I guess I will just hope that someone replies eventually.

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I'm far from and "expert" as the site says ....ask an expert.... so I was hoping I could find some =) It's more that the experts are smart enough to not spend their time on detailed long questions, when theres to many easy to answer ones out there. I just like asking some things, never trying to belittle anyone or anything, just a lot of my answered questions are just wrong! I had one the other day that I broke down to A or B....some one answered "A" I think..... they were wrong....noone took up the opportunity to give a second answer. so its not that there aren't smart folks around us, just not looking or interested I'm guessing.

I even try to help people by using a question with good search engine terms like this question (3% was added for that reason....H2O2 as well and I was sure to use purify AND concentrate, so either way someone may type something it will have a common term - increasing traffic.

whatever.... I'll give some people a chance to answer, just to make it more complete or useful....I wait...and see!

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You should do both, if it interests you! I answer things that I'm sure of, but try to work through.... I have had people explain my error.... your doing great! I was just explaining how crazy the reaction is to such little details - I didn't expect anyone to answer all that. Just figured I'd pass on the knowledge to some who might read it. (I didn't mean to imply....and you didn't ...I know!)

=)

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You can concentrate regular drug store grade hydrogen peroxide by heating it. Keep it below boiling but hot enough so the water evaporates via steam. Eventually, enough water will evaporate to leave you with a more concentrated hydrogen peroxide solution. If you want the specifics, like what temperature to heat it at, I don't know. Somewhere below boiling point; 100º C or 212º F.

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You should probably be careful asking questions like that. I believe concentrated H2O2 can have some unpleasant applications. You might find yourself being visited in the middle of the night by MI5. In fact I wouldn't be surprised if they're watching this thread already, in which case they should at least have the decency to click some ads!

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I didn't mean to imply you were trying to belittle anyone. That's not a thought that crossed my mind. I was thinking maybe I should stick to the medical categories, my real area of expertise, instead of venturing into chemistry. Or research the answer instead of just relying on myself to figure the answer out.

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Hydrogen peroxide is not flammable. I don't know what danger heating it just below boiling would pose.

I'm not adding anything to it. No additives; no bomb.

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I think you are the only person on Mybestanswer qualified to answer your own questions in such detail. I better stick to questions more on the Chem10 level. lol

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Put it in the freezer, the liquid that doesn't freeze is more concentrated, and you can pour it off. I think heating it might be dangerous!

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