What is the procedure to seperate Zinc Sulfate from Manganese Sulfate after dissolving the old zinc carbon battery in dilute sulfuric acid solution
when metallic iron casing is already removed ?
[Edited on 13-3-2024 by nikotyna1939]
The main reasons of using old Zinc Carbon batteries
nikotyna1939 - 12-3-2024 at 23:32
I'm going to use old Zinc Carbon batteries because I BELIEF IN THE 3R PHILOSOPHY REUSE, REDUCE AND RECYCLE!
Also its interesting and to reduce monetary budgets.
EF2000 - 13-3-2024 at 04:08
Manganese(II) can be oxidised to Mn(IV) that precipitates as MnO2. Zinc is already in its highest oxidation state, so it will not oxidise. Something
like:
2 KMnO4 + 3 MnSO4 + 2 H2O→ 5 MnO2 + K2SO4 + 2 H2SO4
(permanganate is not exactly green chemistry, though)RU_KLO - 13-3-2024 at 08:58
as EF2000 stated, the best procedure is to oxidize Mn(2+) to Mn(4+).
Ideally the best thing you do (or I do) is to separate it mecanically. You will have the zinc outher case and the inner MnO2 impure stuff. (+ carbon
rod)
then you can react Zn metal to any acid and proceed from there to purify it. (I keep the metal case, as Zn metal is very usefull as reducing agent.
And you can react it with acids to get the desired sulfate, chloride, etc...
MnO2 is a little though, because all the impurities. I go with "der Alte" process (you will find it in the sticked permanganate post)
1) boil it with water and a little HCl (to remove little Zn), filter.
2) then burn the black "stuff" at +500º (blowtorch or barbacue furnace) to get Mn2O3 -brown stuff (and remove carbon)
3) leach Mn2O3 with H2SO4, filter and cristallize MnSO4 (medium purity) -could contain Iron. Furher cristallization, purify this better.
regarding your question,
if you allready have a CLEAN solution of MnSO4 + ZnSO4, you could try an oxidizer (H2O2 for example) to oxidize MnSO4 to MnO2 , which will
precipitate, leaving Zn2+ in solution)
SnailsAttack - 16-3-2024 at 14:23
in my experience, zinc oxide dissolves readily in vinegar while the manganese oxides don’t dissolve at all. so you could probably use thatSulaiman - 16-3-2024 at 14:36
+1 for the mechanical separation.
I have a couple of zinc pots from a 6v 'lantern battery' only slightly corroded afrer years unattended on a shelf in my shed.
I've never found much use for the MnO2/carbon mess. bnull - 16-3-2024 at 15:54
You can use sodium hydroxide. Ok, it's not exactly the separation of zinc and manganese sulfates, but of zinc and manganese hydroxides.
Zn(OH)2 is soluble in NaOH (and ammonium hydroxide), while Mn(OH)2 is not.
I'm assuming there is an excess of acid and you have a pH indicator, like pH strips or phenolphthalein (I prefer the latter. The indicator is not
really necessary). I'm also assuming that it is a clear solution (because you filtered out all the black powder).
Neutralize the excess acid with a slow addition of sodium hydroxide solution. When you are sure the acid was neutralized (because either you have
checked the pH or a whitish precipitate appeared), make the addition dropwise. At first, a white precipitate of Zn(OH)2 and
Mn(OH)2 will form. Keep stirring during the addition of sodium hydroxide until the precipitate stops dissolving. Filter the solution. The
filtrate is pure manganese (II) hydroxide, while the solution contains sodium zincate and sodium sulfate.
Wash the precipitate to remove NaOH. With the precipitate still in the filter and the filter over a beaker, wash it with enough sulfuric acid to yield
manganese sulfate.
If you used phenolphthalein, you have now a pink solution. Add sulfuric acid slowly until the color disappears. Let the water evaporate and the salts
crystallize. Depending on what you will do with the zinc sulfate, the presence of sodium sulfate is no problem.
soaking the old zinc carbon batteries first in sulfuric acid first
nikotyna1939 - 18-3-2024 at 02:56
what if i soaked the old zinc carbon batteries first in sulfuric acid and filter the solution in buchner funner with 3 layer thick polyester cloth as
the filterbnull - 18-3-2024 at 03:09
You'll have a solution of sulfuric acid, zinc sulfate, and ammonium sulfate in the beaker, and black stuff rich in MnO2 in the filter. And
a little HCl in both air and solution.
You'll have a solution of sulfuric acid, zinc sulfate, and ammonium sulfate in the beaker, and black stuff rich in MnO2 in the filter. And
a little HCl in both air and solution.
[Edited on 18-3-2024 by bnull]
what is the purpose adding HCL this reaction?RU_KLO - 18-3-2024 at 15:58
You'll have a solution of sulfuric acid, zinc sulfate, and ammonium sulfate in the beaker, and black stuff rich in MnO2 in the filter. And
a little HCl in both air and solution.
[Edited on 18-3-2024 by bnull]
what is the purpose adding HCL this reaction?
"A zinc–carbon battery (or carbon zinc battery in U.S. English)[1][2][3][4] is a dry cell primary battery that provides direct electric current from
the electrochemical reaction between zinc (Zn) and manganese dioxide (MnO2) in the presence of an ammonium chloride (NH4Cl) electrolyte" wikipedia
HCl is not added. Its produced from the sulfuric acid you use and ammonium chloride electrolite bnull - 18-3-2024 at 16:28
You don't add HCl. It comes from the electrolyte in the zinc-carbon batteries,which is a paste of ammonium chloride. I thought that naming the
substances that way would be better than talking about ions and you could have a better idea of the products, but I was wrong.
Let's try it another way. You'll have a solution of sulfuric acid with chloride, zinc and ammonium ions in the beaker, and black stuff rich in MnO2 in
the filter. You can recover the zinc and ammonium as sulfates because there's an excess of sulfuric acid and the chloride ions will form HCl and leave
the solution as it evaporates. (Nevermind.)
By the way, does anyone know how much MnO2 and NH4Cl are in the zinc-carbon batteries? I remember reading somewhere that they
used about 30 % of manganese dioxide in the black stuff.
[Edited on 19-3-2024 by bnull]
thanks
nikotyna1939 - 19-3-2024 at 23:13
ok thank you for the full explanationRU_KLO - 20-3-2024 at 04:29
By the way, does anyone know how much MnO2 and NH4Cl are in the zinc-carbon batteries? I remember reading somewhere that they
used about 30 % of manganese dioxide in the black stuff.
[Edited on 19-3-2024 by bnull]
from an eveready msds (a lot of tolerance - or not wanting to give exact formula)
MATERIAL OR INGREDIENT %/wt.
Acetylene Black 3-7%
Ammonium Chloride 0-10%
Manganese Dioxide 15-31%
Zinc 7-42%
Zinc Chloride 2-10%
Non-Hazardous Components Steel 23-28%
Water, Paper, Plastic and Other Balancebnull - 20-3-2024 at 05:10
They're covering all the bases, from common zinc-carbon (no ZnCl2) to heavy duty zinc carbon (ZnCl2 with no NH4Cl).
By the way, does anyone know how much MnO2 and NH4Cl are in the zinc-carbon batteries? I remember reading somewhere that they
used about 30 % of manganese dioxide in the black stuff.
Linden's Handbook of Batteries, 3rd edition, chapter 8 says that:
Quote:
The bobbin [=cathode mix, black stuff] usually contains ratios of manganese dioxide to powdered carbon from 3:1 to as much as 11:1 by weight. Also,
1:1 ratios have been used in batteries for photoflash applications where high pulses of current are more important than capacity.
So, dry black stuff (washed from electrolyte) is ~75-92% manganese dioxide, rest is acetylene black.
Minor detail ;)
Sulaiman - 21-3-2024 at 12:29
Zn + 2 MnO2 + H2O → Mn2O3 + Zn(OH)2
So in a fresh battery you would try to retrieve zinc and manganese dioxide.
The original question related to old (assume exhausted) cells,
so mostly manganese oxide and zinc hydroxide to process. bnull - 21-3-2024 at 14:17
@EF2000: Ooh, I wish I had found that book sooner. Thanks.
@Sulaiman: I had that in mind (old battery, an orgy of manganese oxides) when I suggested NaOH to separate zinc hydroxide from the manganese
compounds. Thanks all the same.
