So I've been reading bubbling chlorine gas through a solution of potassium ferrocyanide is a production method of potassium ferricyanide. But I wanted
to ask if there were other reactions that occur, ie: does the chlorine gas react with dissolved potassium ferricyanide? Or dissolved chlorine gas
create a reaction with ferricyanide (such as to release HCN gas).
I have a solution of potassium ferricyanide and potassium bromide, other times it'll be sodium chloride instead of KBr. I use this for bleaching, in
turn it gets reduced.
It would be practical and cheaper to oxidise it back to potassium ferricyanide for more (but not indefinite), than to keep buying more (~$40+/kg
here). I've already done similar things such as passing SO2 gas through a solution.
So rather than a straight solution of potassium ferrocyanide, it would be a mix of potassium ferricyanide, a chloride or bromide salt as well.
I assume a chloride salt would be best in my use (I could use either)
So I wanted to know if there were any other reactions that would take place that would leavy possibly undesirable products in my solution.
[Edited on 9-5-2011 by Athiril]symboom - 8-5-2011 at 20:07
well chlorine oxidizes the bromide ion to bromine liquid and when you have sodium chloride and bubble chlorine through nothing will happen not to sure
but you might end up with HCN and iron chloride.blogfast25 - 9-5-2011 at 03:46
[...] but you might end up with HCN and iron chloride.
Basically impossible: the Fe(CN)6 (both ferro and ferri) complexes are near perfect and highly stable. They hardly show any of the typical reactions
of Fe2+ or Fe3+. Cl2 does oxidise the ferro complex to the ferri variant.
Heating of ferrohexacyanate with dilute H2SO4 does release HCN, but with conc. H2SO4 you get CO2, so careful with that...
Cl2 also oxidises any halide ions of Br and I.Athiril - 10-5-2011 at 03:31
Good to know, I want to turn back reduced ferricyanide back to ferricyanide, it'd be very easy and useful to do via simple bubbling of Cl2
I can use NaCl instead of KBr as my halide salt in the bleach, it's just a bit slower than KBr for the task I use it for.
[Edited on 10-5-2011 by Athiril]
I assume direct adding of hypochlorite instead of Cl2 gas to the solution wouldn't be what I wan't? Though I can't have any excess hypochlorite in my
solution anyway (it'll destroy my film), so I'll guess I'll stick with gas regeneration.
[Edited on 10-5-2011 by Athiril]woelen - 10-5-2011 at 05:04
Bubbling Cl2 through the solution of ferrocyanide is a good way of making ferricyanide. It actually was used as a preparative method for making
ferricyanide in the past. There hardly will be any side reactions and you do not need to worry about formation of HCN or other nasties.
I'm not sure whether the presence of bromide spoils the reaction. I personally don't think so. If Cl2 oxidizes Br(-) to Br2 then I expect that the Br2
in turn will oxidize any ferrocyanide to ferricyanide.Athiril - 10-5-2011 at 06:41
Actually I think I'll have to stick to KCl or KBr (as I'd end up with KCl then anyway).
As using NaCl would lead me to NaOH I think, then when it comes time to regenerate, I would end up with some NaOCl which I definately do not wan't.
