Author Topic: Concentrating H2O2 by freezing  (Read 3879 times)

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noj

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Concentrating H2O2 by freezing
« on: November 13, 2001, 01:42:00 PM »
I was reading about the properties of H2O2 on a link at Rhodium's, and this is what I found:

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.


This seems to be a simple solution to acquiring a concentrated solution of peroxide even if all you can find is the drugstore 3%.

abc123

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #1 on: November 13, 2001, 03:41:00 PM »
that does seem like a simple way to make your own...in the US 30% H2O2 is sold at pool stores as a shock.
its 10$/gallon......35% at oxygen stores (on net for "better air")

also h2o2 decomposes at high concentrations so an old 10$ gallon bottle would not be worth it

this freezing method I assume would concentrate higher % solutions for example make 30%==>50% ...and if one has a low concentrated solution of a specific carboxilic acid (home-made)...the increase in ROOR would make up for the increase of water in acid.....this method could possibly be very useful for those without proper reagents and/or those in countries without OTC h2o2 (if thats the only means of getting it)

abc123

Dad made whisky and he made it well, cost two dollars....burned like hell......GD

noj

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #2 on: November 13, 2001, 05:23:00 PM »
pool shock is 30% peroxide? I build swimming pools by day, and never knew that.

Gen_Washington

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #3 on: November 13, 2001, 06:42:00 PM »
I've never had 3% peroxide freeze.  What type of dreams you havin' btw?

noj

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #4 on: November 13, 2001, 07:04:00 PM »
the article also says you can vacuum distill off the water. I don't know why it wouldn't freeze, everything freezes at some point.

I thought pool shock was chlorine? The chlorine-free shock treatment contains potassium monopersulphate. What type of shock is H2O2?

goiterjoe

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #5 on: November 13, 2001, 10:00:00 PM »
I've read on model rocket pages that percentages over 70% can be concentrated in the same manner.  I think it went something like you freeze the peroxide into a slush, and filter out the ice/peroxide continually until you're left with a peroxide that is upwards of 90%.

Sed quis custodiet ipsos custodes?

abc123

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #6 on: November 13, 2001, 10:57:00 PM »
the 30% peroxide bottles swim has are allilte old but have been stored in freezer since bying...they have never slushed up...i have read the same thing about freezing it...maybe the temp needs to be lower than normal freezer temps??

normal pool schock is chlorine but a 28% peroxide type is sold for those who dont want chlorine

swim has never used it but was once at a department store and saw many 10$ gallon bottles when looking for something else...swim said he thinks it preety  common but wasnt sure...call around..its definately around...would guess theres high impurities in it but probally less than 3%===>30%....




[impurities could really mess things up in a peroxy-acid rxn especially metals because the peroxide will oxidize it (rust)and boil the whole shit and it would volcano out causing a blinding (acute or up to 7 days to cause blindness), chocking, pulmonary-edema, chemical pneumonia, cop-calling, rug destroying (if not covered), paint staining, cilia hair burning, ant venom peroxide, and evacuating the house type of "smell"....obviously the OTC peroxide doesnt have enough impurities to cause this but the small amount there may be headache in temp problems with DCM....]



Dad made whisky and he made it well, cost two dollars....burned like hell......GD

PrimoPyro

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Re: Concentrating H2O2 by freezing
« Reply #7 on: November 14, 2001, 03:09:00 AM »
Ok, you want TWO great reagents in one OTC product? (US bees for sure, dunno about other countries.)

Well, a product sold at ANY fucking store under the sun, that sells home chemicals (detergents, fabric softeners, dishwasher soap, etc.) will sell a form of drain opener by the bran of Dr***o. Their product called Fo*m*r is a two part product in a bottle that opens drains better than ever before.

On the ingredients list: Sodium Hypochlorite, Sodium Hydroxide, Hydrogen peroxide, Water. (not necessarily in that order, and no percentages stated, I will call and find them out)

But the bottle is split in half vertically, so that its two bottles fused together. The components are seperated, and when poured together, begin to foam. (whooo, neat... :P )

Well, test this: Add NaOH to NaOCl. No foam....
Add NaOH to H2O2. Small amount of fizz. No foam...
Add H2O2 to NaOCl. Fizz and some foam. BINGO.

One half is the NaOH/NaOCl mix, and the other is H2O2 in H2O.

Ive used this brand for CHCl3 from CH3COCH3 via -OCl. It works fine.

Never used the H2O2 for anything. So I dont know the concentration. This brongs me to a question: How would I determine the concentration of a quantity of hydrogen peroxide? What is a good test?

Enjoy

PrimoPyro

Vivent Longtemps la Ruche! STRIKE For President!

terbium

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #8 on: November 14, 2001, 06:59:00 PM »
Measure the volume of oxygen evolved as the peroxide decomposes. A little bit of some metal salt will work as the decomposition catalyst. Cobalt chloride should work perhaps also an iron or nickel salt.

PrimoPyro

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #9 on: November 14, 2001, 07:11:00 PM »
I thought of that too, but couldnt the oxygen be solvated by the water, thus giving me a false reading? And also, this would be assuming a complete decomposition, and without any side reactions of Oxygen absorption.

Considering these statements, terbium, do you think them not to be an issue with the process? If this isnt a problem, then I will try it anyway. Im just asking because I wonder.

                                                 PrimoPyro

Vivent Longtemps la Ruche! STRIKE For President!

terbium

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Re: Concentrating H2O2 by freezing
« Reply #10 on: November 14, 2001, 07:23:00 PM »
Considering these statements, terbium, do you think them not to be an issue with the process?
Yep, those considerations should not be significant. Try some random bottles of 3% drug store peroxide and see what you get; the numbers should be accurate.

Osmium

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #11 on: November 15, 2001, 02:20:00 AM »
Well, in classical analytic chemistry the I2/thiosulfate titration is used all the time, and it is very well suited for H2O2 strenght determination.

terbium

  • Guest
Re: Concentrating H2O2 by freezing
« Reply #12 on: November 15, 2001, 08:52:00 PM »
Yes, for someone with the necessary equipment this would be much more accurate. It was the technique we used when I worked for a company that manufactured organic peroxides.