[KiraPienaar]

Hi Does anyone know of a method that can be used to separate a mixture (solids in a powdered form) of Fe²⁺ and Mn²⁺? I can find many for all the other cations but none that separates these two??

[Hunter2]

Probably treatment with strong oxidiser. Manganese-II will be oxidised to Permanganate. Iron-II to Iron-III. So you have Kation and an Anion. Furthrt tratments with caustic will precipitate the iron as hydroxide. Also ionexchanger could be a possibility.

[snorkack]

Probably treatment with strong oxidiser. Manganese-II will be oxidised to Permanganate. Iron-II to Iron-III. So you have Kation and an Anion.

Unless your oxidizer is strong enough to oxidize iron (in basic solution) to ferrate.

While iron-III is fairly soluble in strong acids and a mild oxidant, manganese-IV is resistant to dissolution and also a strong oxidant. Can you produce reliably and reproducibly conditions where
a) iron is oxidized to Fe(OH)₃ and precipitated, Mn stays in solution as Mn-II?
b) Mn is oxidized to MnO₂ and precipitated, Fe stays in solution as Fe³⁺?

[Hunter2]

to a) not possible, if you alcaline the solution Fe^2´+ and Mn²⁺ will precipitate to the Hydroxides, there will be nothing in solution. Fe(OH)₂ will oxidised to Fe³⁺ by oxygen from the air. So both are not separated.
to b) What kind of conditions ? I think it not possible to get MnO₂ and Fe³⁺ in solution in same time by oxidising.

Ferrate is not stable in acidic conditions. So far I know this can only produced by melting ironoxide and Bariumperoxide.

Permanganate by lead dioxide
http://en.wikipedia.org/wiki/Permanganate

[snorkack]

to a) not possible, if you alcaline the solution Fe^2´+ and Mn²⁺ will precipitate to the Hydroxides, there will be nothing in solution. Fe(OH)₂ will oxidised to Fe³⁺ by oxygen from the air. So both are not separated.

Yes, Fe^2´+ and Mn²⁺ will precipitate as hydroxides - at about pH 6...7. Whereas Fe³⁺ is precipitated about pH 3.

So, in mildly acidic conditions, between 3 and 6, both Fe^2´+ and Mn²⁺ are in solution, but Fe³⁺ is not, and neither is Mn⁴⁺

Are they equally easy to oxidize, or does one of them oxidize and precipitate first?