# Obtain precipitated iron?

Is it possible to obtain pure, precipitated iron with no oxidation by some chemical process?

Alternatively is it possible to electrically purify iron using an anode and cathode?

Is it possible to obtain pure, precipitated iron with no oxidation by some chemical process?

Very pure iron can be obtained by pyrolysis of iron pentacarbonyl. Iron metal obtained in this manner is in fact called carbonyl iron and is commercially available.

$$\ce{Fe(CO)5 -> Fe(s) + 5 CO}$$

Doing this yourself is very dangerous, however, because iron pentacarbonyl is volatile and toxic. The decomposition reaction to produce iron requires high temperatures, and the byproduct is carbon monoxide gas, which is also notoriously toxic.

Alternatively is it possible to electrically purify iron using an anode and cathode?

This is also possible. I don't know about other salts of iron, but to form iron from iron oxides, very high temperatures are required. The other answer mentioned Dr. Sadoway's work. Let me highlight a recent article of his unveiling new anode materials for electrolytic decomposition of iron oxide. At temperatures as "low" as 1538°C, molten iron oxide can by electrolyzed to pure oxygen gas and to molten iron metal using electrochemistry.

Water is not an appropriate solvent for electrochemical formation of iron metal. At potentials low enough to favor $\ce{Fe^0}$ formation from $\ce{Fe^{+2}}$, water is unstable and would be reduced to hydrogen gas.

• Why is iron different from zinc for electroplating? Zinc requires an even lower potential to deposit than iron and yet we electrogalvanize steel all the time. I'm guessing it has to do with electrochemical reaction kinetics (overvoltage), but I'm looking for documentation that this factor really does reverse the thermodynsmic expectation. Mar 5 '16 at 0:07

Sure... here's a an article on it and a patent for the process. In brief, "[Donald Sadoway, the John F. Elliott Professor of Materials Chemistry at MIT] found that a process called molten oxide electrolysis could... [produce] steel as a byproduct... Sadoway's method used an iridium anode... But after more research... the MIT team identified an inexpensive metal alloy that can replace the iridium anode in molten oxide electrolysis."

• Can you give a (brief) summary of what's at the link, please? Otherwise the answer isn't really self-contained. Thanks! Mar 25 '15 at 22:43

Blockquote

using iron sulphate you can use the same technique used for etching to produce iron powder. You attach the positive side of the current to your piece or iron you want to produce the iron from, and the negative side to a piece of iron.

• Did you quote this from somewhere, since I can't find anything? If so, please include a link to your source. Mar 4 '16 at 10:25
• that was from personnel experimenting. People that do etching of metals in this case iron remove the metal by this process mordent.com/etch-howto the iron quickly rusts though so I'm not sure how quickly you would have to remove the deposit. Having said that when I reread your question properly you mean precipitate from a molten state not a solution I think? Mar 5 '16 at 19:05