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toothpick93
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Manganese Dioxide from Manganese Sulfate
Last night I watched NurdRage's video on making MnO2 via MnSO4 and KHSO5 which you can substitute for hydrogen
peroxide to get roughly the same reaction. Problem is I dont feel like buying 1 kg of Potassium Peroxymonosulfate just to use for this so I was
thinking "is there any other chemical with the extra oxygen that could get the same results when I remembered Sodium Percarbonate used for laundry
(much easier to get).
I dissolved the 2 chemicals in separate beakers and then mixed the 2 together thinking not much would happen. Straight away a brown-ish precipitate
formed with some bubbling also. After about an hour of letting it settle the precipitate is a light brown which looks more like Manganese Carbonate.
Does anyone have the equation to this reaction?
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gdflp
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Your precipitate is most likely manganese dioxide. All manganese(II) salts are a white to light pink color, google manganese carbonate. The equation
for your reaction is probably going to roughly be Na2CO3 + H2O2 + MnSO4 ->
Na2SO4 + H2O + CO2 + MnO2
[Edited on 2-19-2018 by gdflp]
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toothpick93
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But Manganese(II) Dioxide is black. Would the colour change when it gets filtered and dried?
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macckone
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This is going to most likely be a classic precipitation reaction
with the MnCO3 partially decomposing ie:
3Na2CO3*3H2O2 + 3MnSO4 -> 3MnCO3 + 3Na2SO4 +
9H2O2
Then the hydrogen peroxide and the manganese carbonate will
react to some extent yielding oxygen, carbon dioxide and
manganese oxide.
This reaction will not yield a pure oxide or a pure carbonate.
Edit by moderator: Removed erroneous quote
[Edited on 2-19-2018 by gdflp]
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blogfast25
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The colour of the end product does indeed depend somewhat on specific preparation conditions and ranges from dark chocolate brown to almost black.
Mn(II) salts are so easily oxidised to MnO<sub>2</sub> that wasting an expensive oxidiser on it is dumb.
Dissolve the MnSO4 in water and precipitate it with an alkali as Mn(OH)<sub>2</sub>, an off white gel. On filtering and drying the product
will be air oxidised acc.:
Mn(OH)<sub>2</sub> + 1/2 O<sub>2</sub> === > MnO<sub>2</sub> + H<sub>2</sub>O
If you are going to use an oxidiser, use bleach (sodium hypochlorite solution).
[Edited on 10-5-2014 by blogfast25]
[Edited on 10-5-2014 by blogfast25]
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Texium
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Just wondering, where did you get your manganese sulfate?
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toothpick93
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I picked up 500 grams of manganese sulfate as a water soluble fertilizer
http://www.manutec.com.au/default.asp?pageid=10&template...
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Texium
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Oh, nice! It looks like they sell quite a few useful chemicals as fertilizer. Too bad they're only in Australia. It seems like all of the fertilizers
for sale in the US are mixtures of a ton of different things, not of much use for chemistry.
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toothpick93
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Here in australia its hard to get your hands on useful chemicals, Looking for the is the key factor about finding things that may come in useful. I
buy my Sulfur, Copper Sulfate, manganese sulfate, Magnesium nitrate from these guys for a cheap price. About $10 for 500 grams
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Texium
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That's nice, I bought copper sulfate at the hardware store, I think it was $12 for 2 pounds as root killer, but they don't have manganese sulfate,
magnesium nitrate, or even sulfur. They did have potassium nitrate though, which I know can be a bit difficult to come by in other countries. I guess
different places have different chemicals that are easier to come by than they are in other places.
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toothpick93
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Yeah I've never came across potassium nitrate as a fertilizer but i know in USA they have it. Only nitrates ive came across OTC is Ammonium nitrate in
ice packs, Magnesium Nitrate in fertilizers. Its very hard finding a good quality fertilizer with little to no contaminates
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Texium
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Yep, it's usually not worth going through the trouble to separate them out.
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toothpick93
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Yeah, too much hassle, you dont always get a good yield so you end up waisting a lot of product and money
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Jesse Pinkman
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Much easier way to obtain manganese dioxide is from alkaline/heavy duty batteries, preferable D size.
The reverse reaction MnO2 -> MnSO4 is more troublesome.
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gsd
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What is Manganese(II) Dioxide ?
It is either Manganese(II) Oxide = MnO
or
Manganese(IV) Oxide = MnO2
gsd
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Texium
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That is what I use. I'm making some manganese chloride with it right now. It takes about 24 hours to complete the reaction and fumigates my back yard
with chlorine.
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bismuthate
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Well, I believe that bleach would react with Mn (II) salts to form MnO2. Here is a link to an experiment where this occurs.
http://woelen.homescience.net/science/chem/exps/bleach/index...
So, that is a pretty cheap way to make some MnO2.
Also the MnO2 in batteries is really impure so it might not work for some things.
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Jesse Pinkman
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If Very pure MnO2 is desired, it can be obtained from MnSO4 by the following method:
"Preparation of gamma-Manganese Dioxide
Manganese (II) sulphate monohydrate (140 g) was dissolved in 2.66 liters of water and heated to 60°C. Potassium permanganate (97.3 g) in 1.85 liter
of water was added over a period of 15 minutes and stirred at 60°C for 1 hour, until manganese dioxide precipitated out. The reaction mixture was
filtered and the residue was washed with deionised water until no sulphate ion was present. The solid was dried under suction for 2 hours followed by
drying at 70°C under vacuum to a constant weight (about 8 days) to give 115 g of a dark brown powder."
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Brain&Force
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Adding some hydrogen peroxide will convert the permanganate back to manganese dioxide in a neutral or basic solution.
At the end of the day, simulating atoms doesn't beat working with the real things...
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blogfast25
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Quote: Originally posted by Jesse Pinkman  | Much easier way to obtain manganese dioxide is from alkaline/heavy duty batteries, preferable D size.
The reverse reaction MnO2 -> MnSO4 is more troublesome. |
You obviously haven't ever done EITHER.
MnO2 from batteries is seriously messy, in part because the battery dry electrolyte contains about 30 % very fine graphite, not mention quite a few
other ingredients. Without serious purification that stuff is good for NOTHING.
[Edited on 10-5-2014 by blogfast25]
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blogfast25
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Woelen created conditions favourable to the formation of permanganate but trust me: if you go easy on the bleach you won't produce any permanganate at
all. The colour is deceptive because of permanganate's insanely high colour intensity: in reality there's almost no
MnO<sub>4</sub><sup>-</sup>, perhaps 0.0001 M or so.
[Edited on 10-5-2014 by blogfast25]
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Jesse Pinkman
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I have disassembled many times heavy duty batteries. You are right the procedure is really messy, but as seen from NurdRage's videos, he has obtained
reasonably pure MnO2 from heavy duty batteries ( http://www.youtube.com/watch?v=knc1lSupAwQ ) . The carbon is mostly in form of a graphite rod. The MnO2 powder has impurities like NH4Cl and
soluble iron salts, which can be washed with water (many videos on YouTube).
From this battery obtained MnO2 he has later produced MnSO4 (with nice pink color) and KMnO4.
Simple further oxidation of MnO2 with bleach will not yield much KMnO4, only in trace quantities. Better way to permanganate is to produce first KClO3
from bleach/bleaching powder then to follow the directions from VersuchsChemie : http://www.versuchschemie.de/topic,10934,-Kaliumpermanganat.... .
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blogfast25
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| Quote: Originally posted by Jesse Pinkman | I have disassembled many times heavy duty batteries. You are right the procedure is really messy, but as seen from NurdRage's videos, he has obtained
reasonably pure MnO2 from heavy duty batteries
From this battery obtained MnO2 he has later produced MnSO4 (with nice pink color) and KMnO4.
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The video says NOTHING about the purity of the product, nor is it guaranteed he used THAT SAME product for the production of MnSO4. But even if he
did, the reduction of the MnO2 with sulphuric acid and oxalic acid would leave behind the carbon, which is there as a conductor and does not react.
I've made MnSO4 from battery crud that way and I can assure you there was plenty graphite in the starting product.
I worked on a commercial project (as a consultant/analyst) for the recycling of battery electrolyte and on one large batch found the Mn content to be
about 27 %. That is much, much lower than the Mn content of MnO2. And that there's a lot of graphite is shown by just how staining this material is.
Alkali batteries may contain less graphite, as carbon reacts with strong alkali. All non alkaline batteries I've taken apart contained much graphite.
He states quite clearly it's NOT an alkaline battery.
Take some of your own battery 'MnO2' and dissolve it in strong HCl and see what happens.
From Wiki on alkaline batteries:
"A cylindrical cell is contained in a drawn steel can, which is the cathode connection. The positive electrode mixture is a compressed paste of
manganese dioxide with carbon powder added for increased conductivity."
So even those contain graphite.
[Edited on 11-5-2014 by blogfast25]
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Zyklon-A
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| Quote: Originally posted by blogfast25 |
You obviously haven't ever done EITHER.
MnO2 from batteries is seriously messy, in part because the battery dry electrolyte contains about 30 % very fine graphite, not mention quite a few
other ingredients. Without serious purification that stuff is good for NOTHING.
[Edited on 10-5-2014 by blogfast25] |
Well yeah, but purification is rather easy. The first time I did it, I simply washed the black crap with water, because the salts in there (zinc
chloride, ammonium chloride ect.) are very soluble. After it dried it, I heated the stuff with a torch in air to burn off most of the carbon. I don't
remember exactly what the yields were, but I weighed it before and after, and it certainly lost mass as the carbon was oxidized by air. I'm not sure
how pure it it, and I'm sure it still contained iron contaminates. Either way, I think it's pure enough for several applications.
[Edited on 11-5-2014 by Zyklonb]
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blogfast25
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Zb:
Considering you can buy decent MnO2 for chips, and even decent MnSO4/MnCl2, it's more a 'rite of passage' for backyard chemists, if you ask me.
Often overlooked is that in spent batteries the Mn is mostly present as Mn2O3, not MnO2. Otherwise the battery (or cell) could not
have delivered its chemical energy.
Also, there's almost always iron present too: and removing that fully is NOT so easy. It can't be done without dissolving (thus reducing) the Mn
oxide.
A full purification to 99+ % purity is quite a kerfuffle.
[Edited on 11-5-2014 by blogfast25]
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