Sciencemadness Discussion Board - Sodium percarbonate & hydrogen peroxide

Sodium percarbonate & hydrogen peroxide

renogaza - 3-10-2018 at 13:52

Hello im new here and i wanna be clear that i only understand chemistry on a purely educational level, im not a professional by any means so go easy on me pls..

i wanted to know what kind of reaction sodium percarbonate (and additionally) sodium carbonate and hydrogen peroxide is in stainless steel and aluminum specifically for washing machines, i cannot determine exactly what kind of alloy the aluminum spider arm is made of. (Assuming its made of Al and not zinc like with samsung)

The goal of my query is to find a (preferably color safe) bleach that will effectively kill bacteria, mold, mildew and any other nasties nestled in the spider arm while not corroding the spider arm, the ss drum or any of the structural steel (and is also safe with rubber and plastic), any help and advice is much appreciated!

AJKOER - 3-10-2018 at 15:57

Boiling aqueous sodium bicarbonate (a very common ingredient to cleaning dishes as it does not leave spots) unfortunately breaks down the NaHCO3 forming functionally sodium hydroxide with the release of carbon dioxide gas. The reaction of aluminum and the created sodium hydroxide is very exothermic resulting the dissolution of the aluminum with the formation of sodium aluminate and production of hydrogen gas.

To demonstrate what I'm talking about, dissolve some baking soda ( which is sodium bicarbonate) in water and place in an open jar. And some flakes of aluminum foil and place in a microwave for 30 seconds. The aluminum foil will be very rapidly attacked, which is obviously not what you don't want to happen in your dishwasher with aluminum products.

Avoid sodium percarbonate products, as per a thread I once did (see http://www.sciencemadness.org/talk/viewthread.php?tid=73626#... ), it is actively not Na2CO3/H2O2 due to additives to boost bleaching ability by creating some very dangerous products (so believe the large print multi-language warning labels!).

Bleach is also very alkaline, so I would avoid using it as well, and definitely do not mix it with baking soda as that produces hypochlorous acid (HOCl), which while great for disinfecting, it breaks down to HCl, which can further react with the HOCl to generate chlorine gas (and water), obviously something to be avoided!

Note, the combination of heat and surfactants (as found in soap/cleaning products) do a great job at killing bugs (by tearing them apart), so I really don't think you have to worry about that so much. In my opinion, focus on not corroding your disk washer and avoid using products not intended for use in your machine.

[Edited on 4-10-2018 by AJKOER]

symboom - 3-10-2018 at 16:36

hot carbonate solutions destroys aluminum heavily I remember doing the experiment with aluminum foil and carbonate of soda was a surprise.also don't use laundry detergent in a dish washer you will dissolve the dishes

[Edited on 4-10-2018 by symboom]

[Edited on 4-10-2018 by symboom]

renogaza - 4-10-2018 at 03:20

So i should just stick to laundry soap/detergent then, no bleaches of any kind? I imagined that at least hydrogen peroxide would be safe..

I cant understand why manufacturers would have such a glaring flaw in the design of even modern washing machines.

Additionally (this is probably an old wives tale but) does salt and vinegar work? Or is it just as bad?

Herr Haber - 4-10-2018 at 04:03

Quote: Originally posted by AJKOER

Boiling aqueous sodium bicarbonate (a very common ingredient to cleaning dishes as it does not leave spots) unfortunately breaks down the NaHCO3 forming functionally sodium hydroxide with the release of carbon dioxide gas. [Edited on 4-10-2018 by AJKOER]

Hey ! For once I understood what you said !
And you're wrong

Heating sodium bicarbonate releases CO2 gas and leave out sodium carbonate.

Sulaiman - 4-10-2018 at 04:28

Based on limited experience I think that there are two 'hygene' problems with dish washers;

The build up of fatty deposits in the drainage pipe collects biological material that decays and makes an awful smell.

Hot sodium hydroxide (or potassium hydroxide, sodium carbonate etc.) would clean the fats out quite efficiently,
unfortunately it would also corrode aluminium quite efficiently.
So surfactants are a good alternative.

Bacteria, mold, fungi, algae or whatever do not adhere well to smooth surfaces, such as plastic, metal, ceramic etc.
Calcium carbonate deposits etc. from 'hard' water forms a nice porous home for nasty things to live in/on.
Most acids (e.g. vinegar) will slowly dissolve the limestone from the surface making colonisation more difficult.

Chlorine-based bleaches kill all known lifeforms,
but may not dissolve the limestone,
so using just bleach will give a clean looking, sterile surface,
that can be an inviting substrate for germs to quickly colonise.

Because there are so many variables that I may not be aware of,
especially what happens beyond the drain hose,
I only use 'recommended' type cleaners,
and resist the temptation to try my own formulations.
Except,
The only diy household cleaner that I have adopted is citric acid,
it does a wonderful job of removing limescale from stainless steel, glass, tiles, etc.
applied as a paste, or as a c0.5M mist/spray, that will irritate eyes, nose, lungs etc.

kettles etc. as a dilute (<0.1M) solution

Citric acid is not too environmentally hazardous,
and does not irritate my skin, eyes or nose too much,
and it is cheap

P.S. I too noticed the apparent bicarbonate-to-hydroxide brain fart,
but sodium carbonate can be considered as functionally similar to the hydroxide in this case.
I too sometimes have difficulty understanding some of AJKOERs posts
- too radical for me

[Edited on 4-10-2018 by Sulaiman]

RogueRose - 4-10-2018 at 05:34

I'm pretty certain the OP is talking about a clothing washing machine. I see a few people mentioning dishes and such.

As for H2O2 and sodium carbonate in a washing machine, I would doubt that there would be a problem with that. What brand is your machine? is it a top or front load?

For one thing many laundry detergents have Na2CO3 as one of the main ingredients in the "soap" and one of the main laundry "boosters" besides borax is "super washing soda" or Na2CO3 (the yellow arm & hammar box). Then you have all your oxi-clean products which have a very large % Na2CO3 as well + H2O2 (ingredient is sodium percarbonate for the most part) so I can't see someone making a machine that can't use this stuff.

As far as using H2O2 bleach, I've seen it around here and it is 3% and it says use 1/2 to 1 cup per load and I just can't see that it would be effective in those concentrations in such a short amount of time.

What I found to be the best is using my normal soap (I make my own laundry soap, it's coconut oil based and fairly strong) plus Na2CO3 and hot water. Let it go through the agitation mode for a couple mins then I allow it it sit for 20-40 mins and then finish the agitation mode and my laundry has been much cleaner after I started letting it sit like that for a bit. I think it gives it time to soften up the nasty stuff.

I've also used regular bleach with colors. On a large load (extra large in some machines) I use ~1/3 to 1/2cup regular bleach. I add the soap and carbonate, fill the machine 1/2 full with water, add the bleach, swish it around a bit then put the clothing in and continue filling. This way there isn't any concentrated bleach on any of the clothing, it is well diluted. I also allow it to sit with the bleach in it as said above. Been doing this for about 5-6 years and am still wearing the same black, navy, red shits, underwear, pants, etc and they aren't faded at all. I do use regular strength bleach 5.25% is considered regular here, it is often not marked, some value brands are about 2.5% or even less and the concentrated is about 8% or so.

I did try using 35% H2O2 at about 1/2 cup on my whites and it seemed to do a good job but I don't think it did any better than chlorox bleach, though it is much cheaper for me. I haven't tried it with colored yet and I might try next time I get some more.

RogueRose - 4-10-2018 at 05:48

Quote: Originally posted by Herr Haber

Quote: Originally posted by AJKOER

Hey ! For once I understood what you said !
And you're wrong

Heating sodium bicarbonate releases CO2 gas and leave out sodium carbonate.

Do you think a washing machine would get hot enough for this to happen? I seriously doubt that it would. Most household water is between 115 and 140 depending on where you like it set. I think some washers have a built in heater now for "sterilization" modes but from what I remember those are pretty pricey and not real common.

I never understood when people talked about how baking soda was the perfect "secret" ingredient for laundry, with just a normal washing machine & normal water, even cold/warm cycles. Some people swear by it, they say it gets their white undershirts (yellow sweat stains) back to looking and smelling new when even bleach and oxi-clean wouldn't even touch the stains... Well I tried this a few times and never noticed any cleaning beyond what the normal soap would do and figured it was someone who owned stock in baking soda producers, lol.

note: I see that baking soda does start to decompose at 50C, I though it was a bit higher like around 75c

I found wiki is confused as well. In one place it states:

Quote:

arbon dioxide production from exposure to heat starts at temperatures above 80 °C (180 °F).[

Pubchem also states slow decomp at 50C but also lists the solid's decomp at 228F..

Maybe it depends upon purity and also what else is in the water, maybe some helps speed up the decomp and other things in inhibit it? I wonder if NaCl would effect it as a lot of baking soda is contaminated with this.

AJKOER - 4-10-2018 at 06:54

Quote: Originally posted by Herr Haber

Quote: Originally posted by AJKOER

Hey ! For once I understood what you said !
And you're wrong

Heating sodium bicarbonate releases CO2 gas and leave out sodium carbonate.

Apparently you did not understand what I said!

Functionally means the now more alkaline solution (due to the the loss of CO2 and yes, the increased presence of Na2CO3) proceeds to consume the Al foil (with vigor).

One can think of the reaction, to understand its behavior in atttacking the aluminum, as follows:

NaHCO3 + H2O --Mild Heat--> Na+ + OH- + H2O + CO2 (g)

In the presence of more NaHCO3 (aq):

HCO3- = H+ + CO3(2-) [amphoteric]

So:

OH- + HCO3- = H2O + CO3(2-)

where the OH- can also react with an added Al source.

[Edited on 4-10-2018 by AJKOER]

macckone - 4-10-2018 at 07:47

In a washing machine, bleach should be added after the water is filled. Some models have a specific addition point for liquid bleach. Percarbonate bleach recommends that it be added to a full washer but says it can be added dry with clothes. I think it would depend on the clothes. My washer recommends mixing percarbonate with water before adding and only adding the portion that dissolves to the bleach dispenser but for whites I add it directly to the dry clothes. Percarbonate has to be pretty strong to impact the oxide coating on aluminum. Remember concentration matters. Concentrated percarbonate in hot water will definitely destroy aluminum but 25g in 40L of water is not very strong. I would not recommend adding dry percarbonate to a washer with aluminum parts and wait and add when the washer is full and dissolve it in water before adding.

As an alternative to kill bacteria, use sodium borate (borax) it is sold as a laundry 'detergent booster'. It will form very small amounts of perborate in oxygenated water so it also has a very mild bleaching action. Borates are quite toxic to many bacteria but relatively harmless to mammals. An added benefit of borates is they reduce water hardness. I haven't really study the reaction, just reading the label.

As far as removing hard water deposits in a washer of any kind either acetic acid (5%) or citric acid (diluted) is recommended. Both are often buffered with the sodium salt in premade scaler removes so they aren't too acidic. Sulfamaic acid is also available as a scale and rust remover but would probably damage aluminum.

ps. for the original poster, percarbonate is safe with stainless steel. It should be safe with aluminum when diluted in warm water. Borax will kill your bacteria and is safer with aluminum if that is your concern. Zinc should also be safe with cold dilute percarbonate solution. Borax is safe with zinc. Dilute chlorine bleach (<.1%) is also safe with stainless steel but not aluminum or zinc.

[Edited on 4-10-2018 by macckone]

Melgar - 4-10-2018 at 11:53

Baking soda is functionally the same as "washing soda" which as any amateur chemist knows is OTC sodium carbonate. Sodium carbonate reacts with dissolved calcium and magnesium ions to precipitate out calcium and magnesium carbonate. This is important, because calcium and magnesium ions are responsible for "hard water", and one annoying thing they do is make soap much less effective. Trisodium phosphate does this too, even more effectively. But that's been banned from laundry detergent in most of North America and Europe and probably other countries too, because it contributes to algal blooms.

So yeah, baking soda will only help with your laundry if you have a problem with hard water. As far as sodium carbonate's effect on aluminum, it's several orders of magnitude less than sodium hydroxide, so you shouldn't worry about it. And the H2O2 would actually SLOW the dissolution rate of the aluminum, by reacting with exposed metal to form the oxide (corrosion-resistant protective layer) rather than the hydroxide (water-soluble).

Finally, another reason sodium carbonate is less corrosive than the hydroxide is that exposed aluminum hydroxide at the surface of aluminum will react with carbonate ions to form CO2, water, and Al2O3. Al2O3 can obviously be dissolved by strong bases, but not nearly as fast as the hydroxide or the oxide-hydroxide will dissolve.

Carbon8 - 4-10-2018 at 17:50

What is a thread split?

Herr Haber - 5-10-2018 at 04:17

Quote: Originally posted by RogueRose

Quote:

arbon dioxide production from exposure to heat starts at temperatures above 80 °C (180 °F).[

Well, no doubt the washing machine can heat water. As far as I know all washing machines have a heating element

As far as I know, washing powder contains sodium carbonate and not the bicarbonate.
I'm supposed to call Solvay, they should know (called 3M yesterday, I saw your gas mask topic after)

In any case, I can confirm CO2 evolution at 60 celsius.
Makes a nice "look, water's boiling below 100 degrees" trick.

Regarding NaHCO3 superpowers, I never quite understood all the hype. Even less when people claim to make a super soap mixing it with vinegar.
I do know that it's effective when poured on moldy carpets and to help fight fungus in general.
Fungus growth is very PH dependant so in this case, I understand it's usefullness.

@Ajoker: One day I'll understand your posts. I'm not giving up !

unionised - 5-10-2018 at 05:18

Quote: Originally posted by AJKOER

That reaction makes sodium carbonate.
Why risk confusing people by saying "functionally sodium hydroxide ".
Sodium hydroxide simply is not formed.

symboom - 5-10-2018 at 07:34

Think about the reaction of hot sodium carbonate it reacts with aluminum foil as if it was sodium hydroxide
What Is going on there. Sodium bicarbonate can not do this.why I stated don't use it in the dish washer due to aluminum kitchenware use is a common.

[Edited on 5-10-2018 by symboom]