Triflic Acid
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How to make manganese nitrate
I’m trying to make some manganese dioxide electrodes, but the only pure manganese source I have is potassium permanganate. How do I reduce this to
the nitrate, preferably without having to make manganese dioxide. That’s just a pain to work with.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
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j_sum1
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I can't think of a way of doing it without going through MnO2, or at least producing some of that as a side product. After all, you are going from
VII oxidation state to II oxidation state. You are going to pass through IV.
For me, I would be hesitant to use up my KMnO4. If it is not too urgent, you could purchase some Mn metal. It is cheap enough.
Edit: here's a link.
https://www.ebay.com/itm/313179285036
[Edited on 7-7-2021 by j_sum1]
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Amos
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Quote: Originally posted by Triflic Acid  | | I’m trying to make some manganese dioxide electrodes, but the only pure manganese source I have is potassium permanganate. How do I reduce this to
the nitrate, preferably without having to make manganese dioxide. That’s just a pain to work with. |
;
This is a rather roundabout (and blasphemous toward the more expensive manganese compound) but you can reduce your permanganate with bisulfite
solution, which will first produce manganese dioxide, but this dissolves on addition of more bisulfite. Any last stubborn bits will disappear after
the careful dropwise addition of cold, dilute sulfuric acid. You could also just start with commercially available manganese dioxide. After
neutralizing this clearish solution with sodium carbonate or bicarbonate, you have manganese(II) carbonate which can be washed and dissolved in dilute
nitric acid, and you're finished; you wouldn't even need to crystallize the product. If you already have manganese(II) sulfate or chloride, begin with
that instead and skip the reducing step.
[Edited on 7-7-2021 by Amos]
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Bedlasky
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Reduction with H2O2 in nitric acid - this will produce pure solution of manganese nitrate.
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Triflic Acid
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Thanks. That will make life much easier. I just got a truckload of permanganate, around 500g. More than I'll ever need. The reason I choose to do such
blasphemy, is because I know that the permanganate is pure. My only MnO2 is battery grade, and terrible for electrodes. I also really don't want to do
any purification of the shitty MnO2.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
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macckone
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Triflic Acid,
The choices are usually work or money.
You can buy it, make it or buy something to make it from.
Honestly the battery grade stuff is better than the pottery grade by a long shot.
It is reasonably pure with the contaminants being carbon, iron oxide, zinc oxide and potassium hydroxide (alkaline) or ammonium chloride
(non-alkaline).
nurdrage has a series on making manganese dioxide electrodes from batteries, including high quality manganese dioxide from manganese sulfate.
I haven't tried it yet, but a shortcut would be adding pirhana solution directly to the crude battery alkaline manganese dioxide, you would have to
keep adding concentrated (30%) hydrogen peroxide to get rid of any graphite.
Sulfuric acid will attack the zinc and iron oxides but not the manganese dioxide if persulfate is present, which is a trick used in this video:
https://www.youtube.com/watch?v=4JXbF4QgxJk
In fact sulfuric acid won't react quickly with manganese dioxide without something like oxalic acid present.
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Amos
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Surely you're not forgetting the potassium nitrate byproduct? With similar solubility to manganese(II) nitrate?
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Bedlasky
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| Quote: Originally posted by Amos |
Surely you're not forgetting the potassium nitrate byproduct? With similar solubility to manganese(II) nitrate? |
Yeah, you're right. I totally forgot that K must go somewhere  . But from MnO2
you get pure product.
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