Sciencemadness Discussion Board - Hydrogen Peroxide Concentration by Desiccant

Hydrogen Peroxide Concentration by Desiccant

Erbium_Iodine_Carbon - 27-10-2012 at 09:49

Hello all,

My apologies if this method has already been discussed; my searches have turned up nothing.

It's very hard to get a hold of >9% hydrogen peroxide where I live, so I need a reliable method to concentrate it. I've read about and tried both evaporation and freezing but neither of these have worked to my satisfaction.

I like the idea of evaporation but I'd like to find a way to reduce the decomposition due to heat. My idea is to place a beaker with some dilute peroxide in a sealed container and surround it with dry CaCl2. Over time, I would expect the water in the peroxide to be sucked up by the desiccant. I would replace (and recycle) the calcium chloride once it becomes excessively wet.

Has anyone tried this? Does it work?
Any comments or suggestions are welcome.

Thanks!

[Edited on 27-10-2012 by Erbium_Iodine_Carbon]

m1tanker78 - 27-10-2012 at 10:17

I recall some discussions where hydrogen peroxide was 'salted out' from a dilute solution. I suspect your desiccant would achieve the same thing (if it actually works).

Freezing is my preferred method for ~18% peroxide because it has been reliable and isn't energy or equipment-intensive.

Tank

Mailinmypocket - 27-10-2012 at 10:42

Well, I don't know if you have any near you but check/ask at health food stores. There are three stores in my city that carry 35% food grade peroxide for about 19$/L. If they don't have any you can often have them special order it for you, no questions asked... I just mention that because I am also in Canada and I find it pretty easy to find, just need to look in the right places

This is the exact product that they all sell, it's made in Edmonton I believe...

http://www.goldtoporganics.com/page14/page14.html

Erbium_Iodine_Carbon - 27-10-2012 at 12:30

@Mailinmypocket:

I've tried a few health food stores in my hometown but the strongest they have is 5% sold as non-chlorine bleach. I'm in Kingston now for school so I think I'll take your suggestion and look around for it. Thanks!

@Tank:

My method would be slightly different in that the salt and peroxide would be separated, with the water in the peroxide slowly evaporating and the calcium chloride absorbing it from the air.

I've attached 2 pictures for clarity, one showing my proposed set-up and the other a graph of percent peroxide in vapour vs. percent in solution, showing that even at relatively high concentrations of peroxide, mostly water evaporates. I got this picture from US Peroxide who claimed to have got it from J.J. Van Laar. Z. Physik. Chem. 72:723 (1910).

plastics - 28-10-2012 at 02:40

Here is a snippit from a paper on chemiluminescence to make high concentration H2O2 starting from 30%, no reason why it shouldn't work with a lower concentration

Attachment: H2O2.pdf (50kB)
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ScienceHideout - 28-10-2012 at 06:45

Quote: Originally posted by Erbium_Iodine_Carbon

@Mailinmypocket:

I've tried a few health food stores in my hometown but the strongest they have is 5% sold as non-chlorine bleach. I'm in Kingston now for school so I think I'll take your suggestion and look around for it. Thanks!

@Tank:

My method would be slightly different in that the salt and peroxide would be separated, with the water in the peroxide slowly evaporating and the calcium chloride absorbing it from the air.

I've attached 2 pictures for clarity, one showing my proposed set-up and the other a graph of percent peroxide in vapour vs. percent in solution, showing that even at relatively high concentrations of peroxide, mostly water evaporates. I got this picture from US Peroxide who claimed to have got it from J.J. Van Laar. Z. Physik. Chem. 72:723 (1910).

I would imagine that it would decompose in the process. That is the main reason why you just can't 'boil it down' as well.

paw_20 - 28-10-2012 at 08:03

Surely you would lose some to inescapable fact that H2O2 decomposes over time, but I see no reason why it would decompose any faster than a solution of peroxide left alone. You're doing nothing to increase the energy of the system, which is why you can't boil it down. It should still be more concentrated that what you started with.

I would however use all the usual precautions for peroxides; make sure that the container in which you are dessicating is protected from light, and also don't actually seal it, in case there is significant decomposition (or keep it under vacuum).

plastics, did the paper say to what concentration H2O2 they were concentrating that 30% solution?

aliced25 - 5-6-2013 at 17:04

Hydrogen Peroxide can be dehydrated by dessicants, there are a number of papers on it, the best one being either H₂SO₄ or Magnesium Chlorate - Mg(ClO₄)₂. There are numerous dessicants that could be used, but vacuum would be an essential component given the difference in vapor pressure.

Attachment: Maas.Hatcher.The.Properties.of.Pure.Hydrogen.Peroxide.I.pdf.I (1.6MB)
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Attachment: Maas.Hatcher.The.Properties.of.Pure.Hydrogen.Peroxide.II.pdf (120kB)
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Attachment: Maas.Hatcher.The.Properties.of.Pure.Hydrogen.Peroxide.III.pdf (536kB)
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Attachment: Kilpatrick.Reiff.Rice.The.Preparation.of.Hydrogen.Peroxide.pdf (198kB)
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Attachment: Titova.etal.Method.for.Concentration.of.Hydrogen.Peroxide.to.Obtain.it.in.Anhydrous.Form.pdf (37kB)
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[Edited on 6-6-2013 by aliced25]

phlogiston - 6-6-2013 at 04:27

Mg(ClO4)2 is magnesium PERchlorate

Bot0nist - 6-6-2013 at 11:56

As far as evaporation goes. The trick is to keep the temp around 180-190F and not higher. Mag stir to prevent hot spots, and bubble some dried air into the solution from a tank pump. I imagine propping up a blow dryer pointed at the surface of the solution whilst heating gently on the hotplate would speed it up wonderfully. I can obtain peroxide very close to 30% with this method in just a few hours. I cant seem to get this concentration with the fractional freezing method.