Use of MnO2

Reference

Quote: Originally posted by awlb2

If I remember correctly MnO2 can be made into MnSO4 safely by reacting with NaHSO4, then fractionally crystallizing the mixture of Na2SO4 and MnSO4 (MnSO4 is much more soluble that Na2SO4).

Although a dubious source the Golden Book of Chemistry Experiments (http://library.sciencemadness.org/library/books/Brent_GBC.pd...) shows the reaction of MnO₂ and NaHSO₄ as a viable way to make MnSO₄ even describing formation of oxygen gas and sodium sulfate as byproducts as expected - look on page 66.

As the book suggests, precipitation of the Mn²⁺ as manganese hydroxide or carbonate is a better idea that fractional crystallization. What Mn compound are you looking to make anyway?

[Edited on 23-12-2016 by awlb2]

Quote: Originally posted by awlb2

Although a dubious source the Golden Book of Chemistry Experiments (http://library.sciencemadness.org/library/books/Brent_GBC.pd...) shows the reaction of MnO2 and NaHSO4 as a viable way to make MnSO4 even describing formation of oxygen gas and sodium sulfate as byproducts as expected - look on page 66. As the book suggests, precipitation of the Mn2+ as manganese hydroxide or carbonate is a better idea that fractional crystallization. What Mn compound are you looking to make anyway? [Edited on 23-12-2016 by awlb2]

This looks much easier than the procedures posted by Nurdrage and on eHow. Precipitating manganese carbonate is a good idea... you could dissolve it in most acids without generating nasty fumes.

Battery gunk MnO₂ + MeOH + H₂SO₄ seemed pretty good from the start. There are a number of papers on this with at least free abstract.

Reductive leaching of manganese oxide ore in aqueous methanol–sulphuric acid medium
https://www.researchgate.net/publication/223760585_Reductive...

Just the gunk/water slurry showed reaction w/ MeOH, a short lived chlorine smell and turned a touch turbid at the top.. Added sulfuric acid and noticed things taking off nicely. No hotter than could be held by hand, small bubbles and a slow fizz. After some time I went back out to check on it, the chlorine smell was gone and some clear crystals had started on the sides of my jug. Little patches branching out from nucleation points. Fewer stout points radiating outward, but not all cottony like Iv'e seen before. Crap pictures this time

Basically just some fun while cleaning up some OLD projects. The battery gunk was from like 3+ years ago. Maybe as much as 5 yrs. Anyhow, have it sitting over night and will check pH etc. tommorow. Already typed this crap up once, forgot and navigated away... Ugh....

1/2 gal jug, 1/4 gal water, 150ml~ MeOH, 6v MnO₂ goop and perhaps 40-50ml sulfuric drain cleaner were roughed together in a few smaller increments to be certain of safety for the initial starting mess.

MnO₂ will chew up acid, oxidizing the Cl- to Cl_{2 (gas)}, SO₂ for H₂SO₄ instead of going quietly. Waste of acid when you give it something to eat instead.

MeOH + MnO₂ + H₂SO₄ -> MnSO4 + oxidized alcohol (CO₂ / H₂O)

My first try ever, with no heating is a breeze. Added, left overnight, decanted, added more to the MnO₂. Doubble filtered first run, left second on bat gunk, to be filtered a replaced untill its gone from jar 1. 2 pulls have been made, on third now. Each removed solution was settled, decanted and filtered before storage to be boiled down later. It is a nice clear sol. with white bits starting to form at the bottom. Looking clean first try

Family is in town so I dont have a back yard to boil stuff down. The guest bedroom faces the yard with one full wall, two windows and a glas door. If im out there, they aint sleeping, means I am not going out there

Quote: Originally posted by violet sin

Interesting microwave results, but it has me wondering if you could just mix in some sugar and nuke it in a porcelain dish or drinking glass... WELL below red heat. Leach products with the acid of your choice. Though I see where you are going with op's desire to get the metal, I'm more interested in the salts sans fumes.

My first reaction to your suggestion was that it may well work at a slightly low temperature because the carbon formed will be more intimately mixed with the Mn oxide but that may only mean dull red heat instead of red heat.

However thinking about it as the sugar decomposes at a temperature much lower than red heat the reducing decomposition products may well reduce the MnO2. Though I suspect red heat will be required to completely decompose the sugar to insoluble products (carbon) that can be easily remove by filtering after digestion with acid.

Perhaps a combination of sugar and sulphuric acid (of a suitable concentration) will reduce all the Mn (IV and III) to Mn(II) as the sulphate without wasting part of the acid as a reducer and not producing SO2 gas.

Side note: the methanol method is interesting particularly if it produces Mn(II)

I decided to try the micro waving sugar and dried battery gunk. About 30 ml of a 2:1 by volume mixture of gunk and icing sugar in shallow steel can.

Initially lots of caramel smelling smoke then more smoke with a dull glow, then ignition with the appearance of a mild thermite reaction accompanied by large smoky flames which subsided to yellow and blue flames. The blue flames looked like zinc burning as confirmed by white deposits on the can and the inside of the oven. It was fullpower (800W) for about 450s.

The mixture is now a porous weak mass. If any manganese metal was produces it probably oxidised as the mass cooled. It needs to be performed in a closed crucible to exclude air and insulated to have a chance of producing a nugget of manganese. It suggests the method has promise.




Mixing the above porous mass with 32% sulphuric produced some slight fizzing with a smell of hydrogen sulphide and a smell I associate with steel dissolving in acid. I was not able to collect sufficent gas to test for hydrogen. Perhaps some Mn or zinc metal was left in the mass.

[Edited on 27-12-2016 by wg48]

[Edited on 27-12-2016 by wg48]

[Edited on 27-12-2016 by wg48]