Sciencemadness Discussion Board

Prussian Blue: I don't believe it!!

jgourlay - 10-11-2013 at 05:24

Howdy all...I've been away from the forum for a while. I got to making a chess set and board, which has taken all my free time for the 2 years! More or less.

Anyway...

I started googling up how to remove Prussian Blue. I had to grind the spine on a straight razor and am having trouble getting the dyechem off.

Google turned up all these results about Prussian Blue pills for removal of cesium from the intestines. Is this some new wonder cure from Chernyobl? Is this serious? People really take Prussian Blue pills? I read an MSDS for Dye Chem years ago and it just screamed "toxic death!!!"

What gives?

blogfast25 - 10-11-2013 at 05:40

Prussian Blue's formula and structure 'look' toxic because of the CN groups but proper Prussian Blue binds these CN groups so tightly the substance is non-toxic. One of its precursors, potassium ferrocyanide (K4Fe(CN)6) binds these CNs so tightly that the stuff is used in food (in small amounts)!

These are examples of 'perfect complexes': they don't show the typical reaction of neither iron nor cyanide.

I have heard something about the use of Prussian Blue as a chemisorber but don't know much about that...

cyanureeves - 10-11-2013 at 07:47

i have a question myself and it goes like this, if potassium cyanide is a pest to get rid of in gold leach ponds why cant it be turned into prussian blue?wouldnt it be safer?it sure as heck would be a beautiful sight and i have read too about ferrocyanide used as anti-caking in food products.

[Edited on 11-10-2013 by cyanureeves]

blogfast25 - 10-11-2013 at 08:12

Quote: Originally posted by cyanureeves  
i have a question myself and it goes like, this if potassium cyanide is a pest to get rid of in gold leach ponds why cant it be turned into prussian blue?wouldnt it be safer?it sure as heck would be a beautiful sight and i have read too about ferrocyanide used as anti-caking in food products.


Well, it should be possible to complex the cyanide with a small excess of a ferrous or ferric salt. No need even to go to Prussian Blue (which is insoluble).

The complexation constant for Fe(CN)64- is 1 x 1042, acc:

http://bilbo.chm.uri.edu/CHM112/tables/Kftable.htm

[Edited on 10-11-2013 by blogfast25]

watson.fawkes - 10-11-2013 at 08:57

Quote: Originally posted by blogfast25  
Well, it should be possible to complex the cyanide with a small excess of a ferrous or ferric salt.
Ferrous sulfate is already used for this purpose. See this document titled Cyanide Destruction by an industrial services company. It's one of six methods; the other all proceed in some fashion around the route cyanide --> cyanate --> carbon dioxide + ammonia. Yet in all of them iron-cyanide complexes are involved somehow, either as a co-product, by-product, or contaminant.

cyanureeves - 10-11-2013 at 10:41

ooh thank you all so much for this info.

Bezaleel - 11-11-2013 at 06:23

Prussian Blue is also used as a way to remove the very toxic thallium from your body, according to wiki. (Link to 2008 article given on wiki.)

One gets the impression Prussian Blue has quite some affinity for elements with group I behaviour, if it also absorbs/binds caesium.