Varungh
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Making pure oxygen from dead carbon zinc batteries
This is based on 4MnO2+heat ----->2Mn2O3+O2
First you take a carbon zinc battery,dead one works too
You open it and extract the black powder.it is MnO2
You then wash it with water.this is important beacause it is soaked in Zinc chloride which is trouble.(basically you filter it)
Then you dry it ,put i in a heat resistant jar and heat it.it will reduce itself and relese
oxygen.
Hey,dont throw the zinc(only applicable if you have new battery).
Dont throw the carbon rod.it can be used for electrochemistry.
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bnull
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Hold on. The black powder is a mixture of manganese dioxide and carbon (acetylene black to improve conductivity, percentages vary). If you heat the
black powder, you'll have a lot of carbon dioxide coming out with oxygen (if any).
Assuming you performed the reaction above, could you please provide us more details on the process? You know, how much powder you used, at what
temperature it was heated and for how long, the test you used to see if the gas was really oxygen and if there was something else.
That said, welcome to the forum.
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Varungh
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Quote: Originally posted by bnull  | Hold on. The black powder is a mixture of manganese dioxide and carbon (acetylene black to improve conductivity, percentages vary). If you heat the
black powder, you'll have a lot of carbon dioxide coming out with oxygen (if any).
Assuming you performed the reaction above, could you please provide us more details on the process? You know, how much powder you used, at what
temperature it was heated and for how long, the test you used to see if the gas was really oxygen and if there was something else.
That said, welcome to the forum. |
I did do the experiment.the brand is a local brand.i did it by heating the powder in a aluminum bottle over a diy alcohol burner. after some time i
removed the small stopper from the lid and bought a candle near it which burned violently. If purity is a problem you can get good MnO2 by buying it
or making it by electrolysis of MnSO4. The electrolysis should be done cold at high current to make powdery MnO2 to make seperaton easier from
substrate. Otherwise it makes beta MnO2 which clings onto substrate.this cleaned one is pretty pure. I will try dissolving mine in HCl to see if it
has carbon or not.
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bnull
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All zinc batteries except alkaline use carbon. That's why they are also called zinc-carbon batteries.
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Varungh
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Yes apparantly it has a little bit of carbon as residue.
Dont think it showed up on the candle test,oh well.
Also (question) can this partially reduce the MnO2 or fully reduce the mno2.will make a nice source of Mn metal.
I do think you can make Pure O2 by converting to Mangnese chloride, and depositing MnO2 on annode with electrolysis. but at this point H2O2
decomposition becomes more viable for those who can get it.
[Edited on 24-6-2025 by Varungh]
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Sulaiman
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a new 'zinc-carbon' cell has a mixture of carbon powder (for electrical conductivity)
and MnO2
discharging the cell reduces MnO2 to Mn2O3
and Zn is oxidised to ZnCl2
so for MnO2 use a fresh cell.
....,............
for some purposes the carbon is not a problem, for others it is.
eg I used it to decompose hydrogen peroxide solution
to measure the gas volume and calculate the original peroxide concentration.
(any C reacting would produce the same volume of gas because
one mole of oxygen is the same volume as one mole of carbon dioxide
and any carbon monoxide would be converted to carbon dioxide)
CAUTION : Hobby Chemist, not Professional or even Amateur
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Varungh
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MnO2 can be purified with relative ease
MnO2+HCl--->MnCl2+Cl2
MnCl2+(potent oxidiser(bleach can do acc to my experiments)) --->MnO2+byproduct
This MnO2 is relatively pure. If metal impurity is to be seperated, it can be added to dil H2SO4,MnO2 does not react, but say iron impurity does.
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teodor
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There are far more cheap ways to produce oxygen.
I mean when you heat whatever you heat with a burner you destroy more oxygen than get.
[Edited on 15-8-2025 by teodor]
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metalresearcher
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| Quote: Originally posted by teodor | There are far more cheap ways to produce oxygen.
I mean when you heat whatever you heat with a burner you destroy more oxygen than get.
[Edited on 15-8-2025 by teodor] |
Indeed, or just electrolyzing water with NaOH or KOH as electrolyte and capture the O2 at the anode. The latter can be the carbon rods from the same
batteries.
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pesco
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| Quote: Originally posted by bnull | | All zinc batteries except alkaline use carbon. That's why they are also called zinc-carbon batteries. |
Both zinc-carbon and alkaline use MnO2-carbon(graphite) mix.
Mix ratio vary.
Zinc carbon name comes from graphite rod as one of the electrodes. Alcaline uses powdered zinc instead.
Edit: misspelling.
[Edited on 7-12-2025 by pesco]
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bnull
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All the alkaline batteries I had the opportunity to disassemble, from a thin AAA to a large D, had a grayish-white paste and no manganese dioxide.
But the graphite rod thing was a blunder. I do that sometimes. Thanks for pointing that out.
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pesco
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The grayish/white/silvery paste is the zinc powder - the positive electrode.
The negative is all that black gunk between the positive electrode and outer steel shell. That black gunk is mix of MnO2 and graphite
soaked in KOH (hence "alkaline") it is the bulk of the battery mass. Not sure how you could miss it.
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pesco
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From Wikipedia (From wikipedia -> https://en.wikipedia.org/wiki/Alkaline_battery
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bnull
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There was none, really. I found it odd by accepted it anyway.
Edit: Have I been dismantling the wrong batteries all these years?
| Quote: | | The grayish/white/silvery paste is the zinc powder - the positive electrode. |
This much I knew. I tried to recover zinc from the paste but forgot it still wet and it became zinc oxide.
[Edited on 7-12-2025 by bnull]
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pesco
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https://youtu.be/vOtvG0fn6bg?si=Sh1YvQLHYI9N2RP3
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pesco
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| Quote: Originally posted by bnull |
| Quote: | | The grayish/white/silvery paste is the zinc powder - the positive electrode. |
This much I knew. I tried to recover zinc from the paste but forgot it still wet and it became zinc oxide.
[Edited on 7-12-2025 by bnull] |
Easy to do. Dissolve in NaOH and then electrolyse the resulting sodium zincate. You will get nice, fine powder of metallic zinc.
Doing the NaOH process is a good way of getting rid of large number of other metals.
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bnull
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I considered doing that but I had no use for powdered zinc back then. The thing is stable and can wait a few more years in my drawer.
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