RogueRose
International Hazard
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H2O2 as bleach replacement in laundry & effectiveness of pretreatment
I know this isn't 100% chemistry related but it has to do with chemicals and how they are used so I thought I would get some opinions on this and see
what others think.
I've noticed that there grocery stores are starting to stock hydrogen peroxide "bleach" as a safe alternative to hypochlorite. The peroxide is 3% and
the directions say to use 1/2 for small to medium load and 1c for large load. I have a hard time believing that when you mix 1c of 3% with 15-20
gallons of water that this would do anything especially since it is added to the fill/wash cycle which can be 10-20mins (20 being a extra long wash
cycle). I've used straight 3% on clothing (liberally applied) that has had blood on it and I know it takes more than 10 minutes for it to work, I'll
let it sit for about an hour and then it often needs scrubbing and more H2O2. I've never seen any discoloration from straight 3% on clothing either,
even dark jeans or shirts. Has anyone used this and has it been effective for you? Is this some kind of psychological thing that people think it is
cleaning/working even though it doesn't do much. People often use too much soap/bleach/etc thinking it will get things cleaner, so maybe this is an
attempt to not have the "pollution" from bleach.
On another note I was thinking about how pre-soaking & pre-treatment clothing really helps when it comes to washing. It pre-softens any dirt and
helps break up whatever is on the clothing. The problem is this you often need a big sink or use the washing machine to pretreat so it can't be used.
I was looking at those vacuum bags used to store things - they compress everything in the bag down to a small volume, it works really well for
blankets/comforters & pillows and also clothing. A similar method is used when making things like surf boards, kayaks, etc - they enclose in a
vacuum bag, draw complete vacuum and then attach a bag of epoxy or resin and the vacuum pulls the liquid into every area inside the bag - then when
cured the bag is removed and the epoxy is dry.
I was thinking that the same method of the vacuum/resin could be used for pre-treatment of clothing - place clothing in a bag, draw vacuum, then make
a mix of H2O2, soap, washing soda & water and then allow it to fill the bag and saturate the clothing. The clothing could pre-treat/soak while
another load is being washed. I'd think this type of thing could be really useful at places like hospitals and nursing homes where the linens &
clothing are often fairly soiled. When they are collected, they go into the vacuum bag & then get the cleaning fluid mix where it sits until
ready to be washed. I've seen laundry services having to pre-clean sheets & clothing and it is very time consuming and labor intensive. I'm
wondering if a setup like this would eliminate that process and make everything easier and cleaner.
The point of using the vacuum for the clothing/linens is that it reduces volume & the amount of cleaning fluid necessary to saturate everything,
maybe by 70-90%.
[Edited on 5-6-2019 by RogueRose]
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AJKOER
Radically Dubious
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Chlorox Oxygen Bleach (with H2O2) costs around $20 and I do not believe it is 3%, higher...and likely is mixed with a carbonate.
Chemistry: On mixing with transition metal rich tap water, some hydroxyl radicals via a fenton (or fenton-like with Mn(ll),...) and also creating the
longer lasting carbonate radicals in the presence of the carbonate ion:
Fe(ll) + H2O2 --> Fe(lll) + •OH + OH- (see, for example, http://www.lenntech.com/fenton-reaction.htm)
•OH + CO3(2-) = OH- + •CO3-
Also:
H2O2 = H+ + HO2-
•OH + HO2- = OH- + •HO2
•HO2 = H+ + •O2- (pKa = 4.88)
•O2- + H2O2 = O2 + •OH + OH-
the above being the Haber-Weiss reaction which is slow, except in the presence of transition metal ions (see http://www.lenntech.com/fenton-reaction.htm).
1/2 O2 (aq) + •CO3- + DOM = •O2- (aq) + CO2 + DOM (slow, likely follows an e- transfer from activated DOM 'Dissolved Organic Mattter' by the
carbonate radical, and not a direct interaction between aqueous oxygen and the carbonate radical, see page 260 in 'UV Effects in Aquatic Organisms and
Ecosystems', an ebook edited by E Walter Helbling, Horacio Zagarese)
CO2 + H2O2 = H2CO4 = H+ + HCO4- (peroxycarbonate ion)
which accounts for most of the bleaching chemistry (more references: search particular reaction above on SM by AJKOER).
Note: Corresponding system based on HOCl in a fenton-type reaction (in place of a fenton based ferrous and H2O2) is much faster.
[Edited on 3-7-2019 by AJKOER]
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clearly_not_atara
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Simply put, H2O2 is much weaker than chlorine. This is however a huge advantage because chlorine reacts with amides:
RCONHR + Cl2 >> RCONClR + HCl
Amides are present in many fabrics, notably wool, silk, nylon and spandex, which are all chemically attacked by chlorine bleach. This causes many
types of clothing to "lose stretchiness" when the carbamate linkages in spandex are attacked by chlorine.
Many dye compounds which are reactive with bleach are unreactive with peroxide. One which isn't is wine, which is often used to "show off" the "power"
of oxygen bleaches by marketers like Billy Mays. Polyphenolic compounds in wine form lots of hydrogen bonds and can be extremely difficult to remove
from fabrics, but they are rapidly destroyed by hydrogen peroxide. Likewise, blood, which contains iron, is rapidly attacked by H2O2.
A particular advantage of bleach in cleaning is its ability to attack unactivated alkene bonds forming chlorohydrins. This has the effect of
converting a lipophilic compound to a weakly hydrophilic one, which assists detergents in removing them from clothing, particularly grease stains.
H2O2 can in theory attack alkenes but usually will not without other catalysts, so some oxygen bleaches may work better than others. Attacking alkenes
is usually good in bleach chemistry because alkenes are never present in fabrics (they react with O2, degrading the fabric) but are often present in
contaminants.
Sodium perborate may be stronger than other oxygen-based bleaches. It has the usual downsides of borates. Other oxygen bleaches use
tetraacetylethylenediamine to transfer acetyl to H2O2, forming peracetate, which attacks alkenes more readily.
Persulfates have not made it into the laundry, perhaps due to their excessive substrate scope. Other peracids are too expensive; nitrogen compounds
are too reactive; other halogens will still attack amides. Aqueous ozone has been tried, but requires a $300 machine that falsely claims to replace
detergent.
I tried using medical peroxide to remove a grease stain on my hoodie. It didn't work. Hypochlorite would probably damage the sleeve. Not sure which
one of those funny products to go for, but I've wasted enough time reading about the chemistry :p
[Edited on 04-20-1969 by clearly_not_atara]
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AJKOER
Radically Dubious
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Turn your normal acidic H2O2 (high pH hydrogen peroxide is unstable, hence the addition of H3PO4 to lower pH) into a radical generator to remove the
toughest stains by adding nontoxic and friendly (you cannot use these words in the presence of tetraacetylethylenediamine employed with H2O2/Na2CO3
Oxygen Bleaches, as is evident from the warning labels) photocatalytic MgO or ZnO (see, for example, https://www.hindawi.com/journals/jnm/2014/532317/ ) to your H2O2 in the presence of ordinary strong sunlight!
Here is a related source reference study, ‘Photoassisted bleaching of dyes utilizing TiO2 and visible light’, by Gary A. Epling and Chitsan Lin,
published in Chemosphere 46 (2002), p. 561–570, based on TiO2 at http://nathan.instras.com/documentDB/paper-253.pdf which I did not cite owing to possible availability and cost issues of the photo catalyst.
This source details a preparation of a related ZnO microstructure at https://reader.elsevier.com/reader/sd/pii/S0022369718316123?...
Note, adding the HCO3- ion may assist with the formation of the albeit less powerful, but more selective and long lasting carbonate radicals.
-------------------------
Exploration of the underlying chemistry starts by noting that a photocatalyst in light is capable of producing electrons, e-, and electron holes, h+
(see, for example, http://www.imaging.org/site/PDFS/Papers/1999/PICS-0-42/1080.... ). This leads to solvated electrons which, in the presence of dissolved oxygen
(from say air or decomposing H2O2), can form superoxide:
O2 (aq) + e-(aq) = •O2- (aq) (reversible)
Also superoxide from the action of an electron hole on HO2- via:
H2O2 = H+ + HO2-
HO2- + h+ = •HO2 = H+ + •O2- (aq) (if pH > 4.88)
Or, possibly superoxide from the action of an electron hole on water, creating the hydroxyl radical, which further acts on H2O2:
(H+ + OH-) + h+ = H+ + •OH
•OH + H2O2 = •HO2 + H2O (see https://aip.scitation.org/doi/10.1063/1.2943315 )
•HO2 = H+ + •O2- (pKa 4.88)
•O2- + H2O2 = O2 + •OH + OH-
the above being the Haber-Weiss reaction, as I noted previously above, albeit slow, except in the presence of H+ and transition metal ions commonly
found in tap water (and more so, from water sourced from your metal hot water heater).
[Edited on 4-7-2019 by AJKOER]
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