mkochsch
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Making Ferric Citrate newbie
Is it possible for an amateur chemist to make ferric citrate without too much fuss? On hand I have both Sodium Citrate and Ferric Chloride. Does
sodium citrate mixed with ferric chloride equal, ferric citrate + sodium chloride? How would I precipitate the sodium chloride out of the solution.
How about steel wool and citric acid. How would that work, if at all. Thanks.
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guy
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Yes steel wool and citric acid would work, but that takes a LONG time. Sodium citrate and ferric chloride will not work since NaCl and iron(III)
citrate are both soluble. You can add sodium carbonate and then add citric acid.
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chromium
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I have not done this so i do not know for sure.
You may try to react ferric chloride with sodium carbonate or hydroxide. Ferric carbonate (or hydroxide) is insoluble in vater and is easy to purify
and separate. Then react it with citric acid. Another probable way is electrolysing citric acid solution with iron anode. Its rather fast but i do not
know side ractions and purity of product.
[Edited on 16-12-2005 by chromium]
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mkochsch
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| Quote: | Originally posted by guy
Yes steel wool and citric acid would work, but that takes a LONG time. Sodium citrate and ferric chloride will not work since NaCl and iron(III)
citrate are both soluble. You can add sodium carbonate and then add citric acid. |
So mix the ferric chloride with sodium carbonate -- in a solution of water. That will make ferric carbonate (solid) and sodium chloride (liquid) which
I can filter and wash with distilled, right? Then mix ferric carbonate in a solution of citric acid which should give me ferric citrate and what
by-product comes from the carbonate?
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chromium
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Byproduct that comes from ferric carbonate and citric acid is CO2 gas.
Problem may be that ferric carbonate supposedly is rather amorphous and it may take forever to filtrate all water out of it. But you need not
eliminate all the water. Just wash precipitate several times to remove sodium chloride. Ferric carbonate must be reacted with citric acid within few
days as it may become rather inert if it stays long time.
[Edited on 16-12-2005 by chromium]
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12AX7
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Hum, you'll probably get ferric chlorohydroxides. Like precipitating a copper chloride solution.
Just find some rust 
Tim
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mkochsch
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| Quote: | Originally posted by chromium
Byproduct that comes from ferric carbonate and citric acid is CO2 gas.
Problem may be that ferric carbonate supposedly is rather amorphous and it may take forever to filtrate all water out of it. But you need not
eliminate all the water. Just wash precipitate several times to remove sodium chloride. Ferric carbonate must be reacted with citric acid within few
days as it may become rather inert if it stays long time.
[Edited on 16-12-2005 by chromium] |
I should have mentioned that I don't need powdered ferric citrate out of this. A working solution is just fine. I only need a small amount too, say
100 ml. How do I calculate the ratio of how much ferric chloride and sodium carbonate (or sodium hydroxide) to mix together?
[Edited on 16-12-2005 by mkochsch]
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Swany
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Stoicheometry, learn that and find a calculator and a table of atomic weights to calculate the needed amount/ratios of each respective reagent.
100mls isn't *that* small of an amount.
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woelen
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Keep in mind that ferric citrate is not a simple compound. In reality you get a citrato complex of indeterminate composition. The commercial product
usually is "ammonium ferric citrate", but this is a complex, which can be green or brown, depending on the citrate/iron ratio.
Also keep in mind that solutions of "ferric citrate" are very prone to mould. I once has a solution of brown "ferric ammonium citrate" and after a few
weeks it was horrible. All kinds of moulds, hairy and stinky, were in the solution. A frequently used method of preventing this moulding is addition
of a few crystals of thymol. This does not form complexes with iron (III), such as phenol does, but it has the preserving properties of phenol.
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mkochsch
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| Quote: | Originally posted by woelen
Keep in mind that ferric citrate is not a simple compound. In reality you get a citrato complex of indeterminate composition. The commercial product
usually is "ammonium ferric citrate", but this is a complex, which can be green or brown, depending on the citrate/iron ratio.
Also keep in mind that solutions of "ferric citrate" are very prone to mould. I once has a solution of brown "ferric ammonium citrate" and after a few
weeks it was horrible. All kinds of moulds, hairy and stinky, were in the solution. A frequently used method of preventing this moulding is addition
of a few crystals of thymol. This does not form complexes with iron (III), such as phenol does, but it has the preserving properties of phenol.
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But Ferric Ammonium Citrate and Ferric Citrate are two different compounds. For what I'm doing only the latter will do. Good point about the shelf
life. Once I either synthesize or buy ferric citrate it will be ending up in another solution which is resistant to mould, hopefully.
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mkochsch
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| Quote: | Originally posted by chromium
Byproduct that comes from ferric carbonate and citric acid is CO2 gas.
Problem may be that ferric carbonate supposedly is rather amorphous and it may take forever to filtrate all water out of it. But you need not
eliminate all the water. Just wash precipitate several times to remove sodium chloride. Ferric carbonate must be reacted with citric acid within few
days as it may become rather inert if it stays long time.
[Edited on 16-12-2005 by chromium] |
What about the steel wool and citric acid idea, but with the addition of hydrogen peroxide? Would the hydrogen peroxide speed things up? Would CO2 be the by product as well?
[Edited on 17-12-2005 by mkochsch]
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guy
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| Quote: | Originally posted by mkochsch
What about the steel wool and citric acid idea, but with the addition of hydrogen peroxide? Would the hydrogen peroxide speed things up? Would CO2 be the by product as well?
[Edited on 17-12-2005 by mkochsch] |
Yes that would make it go faster. CO2 wont be evolved. Thats impossible. The reaction is iron getting oxidized to the hydroxide and then reacting
with an acid to form the salt and water (acid base rxn).
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unionised
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"CO2 wont be evolved. Thats impossible"
Actually, it's perfectly possible, but unfortunate. H2O2 in the presence of Fe++ gives rise to hydroxyl radicals which will chew lumps out of the
citric acid. (Fenton's reagent is a similar mixture used to oxidise organic material).
Ferric carbonate barely exists- what you would get from FeCl3 and soda is a mixture of hydrated Fe+++ oxides and CO2.
Washing that ppt by filtration or decantation then disolving it citric acid should work.
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woelen
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| Quote: | Originally posted by mkochsch
But Ferric Ammonium Citrate and Ferric Citrate are two different compounds. For what I'm doing only the latter will do. Good point about the shelf
life. Once I either synthesize or buy ferric citrate it will be ending up in another solution which is resistant to mould, hopefully.
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Yes, they are different compounds, but the problem with non-stoichiometry also will exist for ferric citrate. The problem is not in the ammonium ions,
but in the ferric/citrate combination. This is quite common in fact for many transition metals. A similar 'ill-defined' compound is ferric oxalate.
You have to keep another thing in mind besides the moulding. Ferric citrate is light sensitive. This is exploited in the cyanotype process
(blueprints). When a combination of ferric ions and citrate ions (or better: a citrato complex of iron (III)) is exposed to light, then an internal
oxidation reduction occurs, with formation of Fe(2+) and breakdown of citrate ion.
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