AJKOER
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Sodium Percarbonate Commercial Products - Some Comments
First, unlike Sodium perborate, Sodium percarbonate is chemically just an addition compound of Na2CO3 and Hydrogen peroxide.
Also, while Sodium carbonate and Sodium percarbonate (basically Na2CO3 and 3Na2CO3.2H2O2) are often listed as the main ingredients in typical chlorine
free bleach, an additive, TAED, which acts as a key activator (see, for example, https://en.m.wikipedia.org/wiki/OxiClean ) is not even listed on the label. TetraAcetylEthyleneDiamine is apparently commonly employed as a bleach
activator in many laundry products (see https://en.m.wikipedia.org/wiki/Tetraacetylethylenediamine ). TAED reacts with H2O2 in alkaline conditions (referred to as perhydrolysis)
creating, in part, Peracetic Acid. The latter PAA is actually preferred over sluggish H2O2 for bleaching. In other words, it is not the H2O2 as the
active bleaching agent, but PAA created in situ. So, other than possibly misleading implying that eco friendly hydrogen peroxide is the active agent,
it is, in reality, PAA, a probematic compound with associated health concerns (see Marquand, E. C.; et al. , 2007. "Asthma Caused by Peracetic
Acid-Hydrogen Peroxide Mixture". J. Occup. Health. 49 (2): 155–158.). Here is a MSDS on an actual PAA mix ( 76-61% water, PAA 20-35%, 3% Acetic acid
and 1% H2O2): https://www.google.com/url?sa=t&source=web&rct=j&... which is far from friendly but does eventually totally decompose into harmless O2,
CO2, H2O,...
As such anyone using a commercial percarbonate product should at least be aware of safety issues and that one is likely employing a Peracetic acid
mix.
Legally, I find it is interesting that one can list main ingredients and not actualy cite active agents. The warning labels on the product are
certainly ample and displayed in different languages, and should not be dismissed under the misconception that this is just a harmless washing soda
and H2O2 mix (that is, absent TAED, which it may approach under totally dry condtions) but apparently, in the presence of TAED, moisture (like in ones
lungs), water vapor or in water solutions, it may no longer be quite so friendly.
[Edited on 23-4-2017 by AJKOER]
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Chemetix
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That, in modern terms, is known as an alternative fact.
Interesting observation, and it did always make me wonder about how "percarbonate", worked...if at all.
Hydrogen peroxide will oxidise certain things under pure conditions but in a laundry situation I though ' it would have to be catalytically decomposed
quicker than it could chemically work to oxidise a stain.' Well that's one less supermarket aisle daydream I'll have now.
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AJKOER
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Actually, I just realized that as PAA is incompatible with even small amounts of transition metal salts (per the referenced MSDS, as is H2O2). So the
main catalytic agent by weight here could actually be ones transition metal contaminated hot water that is feed into the washing machine, further
reacting with PAA (an organic peroxide). The expected Fenton-type reaction could produce hydroxyl radicals (or carbonate radicals) to aid in stain
removal.
Unsaid, however, is that reactive radicals could also attack the fabric itself. The latter becomes evident after many washes with clothes increasing
worn down.
[Edited on 23-4-2017 by AJKOER]
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softbeard
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Why are you going on about "peracetic acid" in a mix containing sodium carbonate? You do realize you won't have much PAA in an alkaline sodium
carbonate environment. I think you're missing the forest for the trees.
I believe the 'activator tetraacetylethylenediamine', aka EDTA, is there precisely to sequester heavy-metal cations by chelation, so that they don't
catalyze the destruction of the peroxide.
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AJKOER
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Softbeard:
Read the referenced Wikipedia commentary in two article on which I provided links.
I agree with your comment that PAA (and/or unreacted H2O2) will further react forming safe products.
The bleach activator is TAED, not to be confused with EDTA, leading to the formation of PAA.
In my opinion, a close look at the warning labels on an OxiClean product appears to support the contention in the Wikipedia article that something
other than Na2CO3/H2O2 may indeed be the active agent, as both individually sold Washing Soda and dilute Hydrogen peroxide (this is different,
however, from the more concentrated OxiClean powder) seem to have relatively tame warning labels.
[Edited on 1-5-2017 by AJKOER]
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softbeard
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You're right, AJKOER, TAED is not EDTA. I had not seen TAED before.
I still find this Wikipedia article suspect in claiming any role for peracetic acid in an alkaline media, as in the presence of sodium carbonate. As
far as I know, the peracetate anion is not a species.
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