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teodor
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Quote: Originally posted by bnull  |
"The structure of PBS [sodium perborate] corresponds to a six membered heterocyclic dianion. PCS [sodium percarbonate], on the other hand, is
not a true percarbonate, but is a perhydrate (Na2CO3*1.5H2O), as shown in Figure 2.9. [...] Its rather
confusing name has arisen because of historical uncertainties over its structure and PCS should be considered as a solid form of hydrogen peroxide
like UHP [urea-hydrogen peroxide]." Craig W. Jones. Applications of Hydrogen Peroxide and Derivatives, pp. 41-42
"Apart from sodium and carbonate ions, the structure determination has shown the presence of hydrogen peroxide molecules which are
hydrogen-bonded to the carbonate ions, and therefore the compound is not a true 'percarbonate.' " Corrondo et al. X-Ray crystal structure of the industrial bleaching agent ‘sodium percarbonate’(sodium carbonate–hydrogen peroxide (2/3))
As for the Wikipedia image, it's only a (wrong) model for the crystalline structure at 100 K. The right one is described in Acta Cryst. (2003). B59, 596-605.
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Interesting. Thank you for pointing to the correct crystall data.
So, we need some inert solvent with stronger hydrogen bonding than Na2CO3 and that one which is not miscible with water.
This is interesting: https://pubs.acs.org/doi/pdf/10.1021/ja02260a013
Actually, the data from the article suggests interesting experiments of purification of H2O2 by solvent extraction.
[Edited on 23-1-2024 by teodor]
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Tsjerk
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Or just destroy the carbonate, in very little water. Giving concentrated peroxide, as discussed.
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clearly_not_atara
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| Quote: Originally posted by teodor | But making a solution will spoil the whole process which will now be the same as concentrating H2O2 solution by distillation. If percarbonate contains
traces of transitional metals (and it likely contains Fe) the distillation is hard to do without decomposition because it requires not only solution
but also glass be completely free from transitional metal ions.
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The use of phosphate will also precipitate any transition metals. Also, I strongly doubt there is much Fe, it would color the salt, and probably stain
the clothes it's meant to be used on. In general, a laundry product like percarbonate should avoid transition metal contamination because A: it stains
clothes and B: it pollutes the environment.
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bnull
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| Quote: Originally posted by teodor |
Interesting. Thank you for pointing to the correct crystall data.
So, we need some inert solvent with stronger hydrogen bonding than Na2CO3 and that one which is not miscible with water.
[Edited on 23-1-2024 by teodor] |
You're welcome. Quinoline seems to be a good candidate. It is soluble in hot
water but not in cold water; it boils at 237°C; it dissolves hydrogen peroxide very well; vapor pressure of 0.06 mmHg at 25°C
(H2O2: 1.97 mmHg at 25°C).
This is a possible procedure: dissolve the percarbonate in the minimum amount of water, add quinoline, mix throughly, decant the carbonate solution,
vacuum-distill the peroxide. Here's two questions: is quinoline cheap and common enough in Sweden; will it react with the peroxide on heating?
Why decompose the carbonate if we can precipitate it?
The OP suggested calcium chloride for dessication. He can use it to precipitate the carbonate out of the solution since calcium carbonate doesn't seem
to complex peroxides. Then it is only a matter of getting rid of sodium chloride and vacuum-distilling the stuff. He'll have to distill it anyway.
And accelerate the decomposition of the percarbonate. Most of the patents I looked dealt with the issue of iron contamination.
I wonder what's the percarbonate the OP has. If it is the household stuff, there're enzymes and alkylbenzenesulfonate in the mix.
Another source for the forum library: Defense Technical Information Center.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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