Separation of Manganese dioxide from carbon

[rogerxd45]

ok so in a cabon zinc battery there is a graphite anode and a zinc case as the cathode. in between these two you have a mixture of carbon and Manganese dioxide.

so after harvesting the cathode and anode (i use the graphite rod for electrolysis) i have a bunch of left over carbon/Manganese dioxide mixture.

 

so i was wonder if there is a way to seperate the two? i mainly would like the Manganese dioxide so if the process ruins the carbon in the mixture i dont care.

 

I really dont have a need for the Manganese dioxide but i figured since i have it i might as well try to extract it and save it incase i do have a use for it in the future.

 

any help would be great! thanks

[Horza2002]

You could try bubbling oxygen gas through it and try and oxidise the carbon to carbon dioxide....that might work....but I guess you'd also run the risk of oxidising the manganese too...

[John Cuthber]

You could try bubbling oxygen gas through it and try and oxidise the carbon to carbon dioxide....that might work....but I guess you'd also run the risk of oxidising the manganese too...

 

Just how often do you normally see oxygen attacking carbon under normal conditions?

It would work if you heated it (about red hot, like a coal fire, would do it) but the MnO2 would decompose.

Air won't oxidise Mn further than Mn(IV) except under strongly alkaline conditions.

[Horza2002]

I never said do it at standard conditions though did i! And to be honest I didn't consider that the MnO2 would decompose if you heated it like in a blast furnace

Edited February 3, 2010 by Horza2002

[rogerxd45]

is it possible to convert it to manganese chloride by reacting it with HCL and then filtering the solution to get out the carbon?

[John Cuthber]

Yes, but be aware that it will give off lots of chlorine.

[rogerxd45]

Yes, but be aware that it will give off lots of chlorine.

 

isnt the chlorine bonding with the manganese?

[John Cuthber]

Half of the Cl bonds to the Mn.

 

MnO2 + 4 HCl --> Cl2 + H2O + MnCl2

[UC]

Take it from experience, the MnO2 in batteries is calcined and highly crystalline, resisting attack by acids, reducing agents, and almost anything you can throw at it in aqueous solution. One option is to simply finely powder the crude battery MnO2/C mix in a molten sodium or potassium hydroxide fusion with an oxidizing agent like a nitrate. Add very slowly. This will generate a melt of a manganate. Once cooled, this can be dissolved in acidic solution (don't use HCl or you'll get chlorine gas), and adding a reducing agent like bisulfite will convert it to soluble Mn (II) ions (be warned that manganese (II) sulfite trihydrate is a poorly soluble solid, so don't use a large excess). At this point, any remaining graphite (if it survived the molten nitrate) can be filtered off. However, this is *extremely* hazardous and unless you have experience working with molten lye and appropriate safety equipment, I absolutely do not recommend it.

 

It's much easier, cheaper, and less time consuming to find a source of manganese (II) sulfate (used as a manganese source for hydroponics) or potassium permanganate and use that. Manganese dioxide from pottery supply places (used for glazes) is graphite free but is the same calcined difficult-to-use material as in the batteries.

 

I've done the molten lye process before. It was a waste of my time to be honest. For a few dollars you can get more [ce] MnSO4*4H2O [/ce] than you'll ever use. Considering you don't need to pay for sodium hydroxide, sodium nitrate, acid, and bisulfite that way, the prices are probably fairly close.