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Thread: Dissolved iron in water--how to extract?

  1. #1 Dissolved iron in water--how to extract? 
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    Given the situation where there is a large amount of dissolved iron (oxidation state of 0) in water, and given that the percentage of iron is increasing, what is the best way to extract or plate out the iron?

    Conditions: H20 and dissolved iron. No other elements or compounds.

    How does iron precipitate out in water? Does it form crystalline structures as would salt or sugar?

    I'd prefer not to employ the use of any chemicals, if possible. I'd also prefer not to boil away the water, as that would require a lot of energy.

    Can the iron be retrieved via electroplating? Does that work if the iron has an oxidation state of 0?

    I realize all of you might be asking, "How would such a situation ever happen?" The answer to that is a long story, and I'm trying to skip that for brevity.

    Thanks!


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  3. #2  
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    I just learned that dissolved metallic iron in oxygenated water (I know--I neglected to mention the presense of oxygen in my previous post) creates compounds such as,

    4Fe()OH)3, 4Fe(OH), and 4Fe3+

    So, the iron won't just sit there in the water, but will react with any dissolved oxygen and form oxide compounds.

    Can magnetism be used to extract the iron from the water Only a few metals are magnetic: iron, nickel, cobalt, and Gadolinium. Couldn't a magnet be inserted into the solution and all the dissolved iron be attracted to it?

    Are iron oxides magnetic, or is it only pure iron?


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  4. #3  
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    Okay, so NOW I've learned that ordinary iron rust (Fe203) is not magnetic. Therefore, to extract the iron from the water using magnetism would only work if the dissolved iron were in the pure iron (oxidation state +0) state.

    Is the above statement true?

    Thanks.
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  5. #4  
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    Even if it were magnetic I don't think that it would do any good in this situation. The best thing to do would be to use a chelating agent, they are molecules which bind strongly to metals potentially allowing it to be removed by filtration or smoething.

    Actually it seems that you can use potassium permanganate to oxidize the Iron so that it will crash out of solution forming small ammounts of solid iron which van then be removed by filtration using activated carbon.

    It would help if you could mention why you needed this done, as I could esaily tell you to do somethingsilly or dangerous and not know any better lol.
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  6. #5  
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    Farmboy,

    Thank you for your great response. I am writing a science fiction novel that features, in part, some exotic chemistry. I want to minimize the fictional portion of what is happening in the story.

    This is very hard for writers to do. To write good science fiction, one almost must be a chemist, or physicist, or an engineer. I'm a mechanical engineer, but am weak in chemistry. College chemistry was 25 years ago for me. They had just discovered atoms at that time, if I recall.

    The only part of the story that I want fictional is how the Fe is forced to have only an oxidation state of +0. My story covers all that...which I am skipping here for brevity. But, GIVEN that, I strongly desire that everything that follows be factual.

    I'm leery of chelating and using oxidizers like potassium permanganate, because those won't work if the Fe cannot oxidize...right? (given the Sci-Fi premise) And if it suddenly can, won't it immediately turn into Fe2O3 if it's in an aqueous slurry in the presence of O2?

    How do I get the Fe away from everything else and put in a pure H2O (with no dissolved O2) so the chelating or permanganating will work before the Fe turns into Fe2O3?

    This is why I'd hoped the magnetic method would work...as this way ONLY the pure Fe will be drawn to it and none of the Fe2O3 and the other gunk in the iron oxide slurry. This also makes for a much more interesting story because no chemicals are used.

    Can magnetism not work for pure Fe in solution when it isn't in the form of big hunks but rather is near atomic-sized tiny fragments that got liberated from its various iron ore compounds?

    Does this clear things up?

    Thanks
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  7. #6  
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    I couldn't say for certain dude, but I don't think that magnetism would work. Iron's magnetism is related to the cumulative effect of all the unpaired electrons which act together when it is a solid. In solution the iron will exist in ionic form (I presume) so no magnetism. This is not my area of expertise though, so you should maybe verify that yourself lol.

    With the rest of the stuff, about the Iron oxidations states and that, why is it that you don't think the iron will be oxidised. Do you mean that you just want it that way or that you really don't think that would work? If it is just the latter, then never worry that technique will work. I think lol.

    Now I'm not sure about the Fe(0) part, I presume you know that it is soluble in water? Assuming that is in fact true then I don't see any reason why you cannot just go from Iron(0) to Fe(3+) using an oxidising agent. In water Iron is normally in the plus two oxidation state, so the reaction would just be Fe(II) goes to Fe(III). You could use potassium permanganate if you wanted or go with something else depending on the scenario you are thinking of. Now this will produce Fe2O3 like you mention, but that isn't too much of an issue, this is one of the natural forms that iron comes in anyway so I think you just need to cook it for a while in a blast furnace to get pure iron back again. So I'm not sure here actually, is it the iron you want to save or are you just trying to clean the water lol, should probably have thought to ask that a little sooner.

    What is the story about if you don't mind me asking. I know a couple of interesting facts that are related to this area, might be of interest lol. When life first evolved on earth there was little or no oxygen in the atmosphere, and so life made use of the abundant and water soluble Iron (in the +2 oxidation state) to transport oxygen (like in haemoglobin). But then all those pesky plants and trees began releasing oxygen into the atmosphere producing the oxidising atmosphere we have now. An unfortunate side effect of this was that most of the iron on earth was changed into +3 which is insoluble in water meaning that it was not biologically available anymore. So life was forced to develop a type of chelating agent known as the siderophores which bound strongly to Iron(III) allowing it to be absorbed into biological systems. Thought it was humerous just that you are finding it necessary to work out how to do the same thing 3 or 4 billion years later lol.

    I think that is all accurate anyway, might be worth fact checking anything I have mentioned here anyway dude lol.
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  8. #7  
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    farmboy,

    You are telling me very good, practical information. But, if there were a case where there were Fe(0+) atoms in a solution, and they couldn't react with anything else in solution, and their percentage in the solution kept increasing, what would eventually happen?

    What if Fe(+0) atoms were added to a molten Na and Ga solution. As more and more Fe(+0) atoms were added to the the solution, I would think that SOMEthing would happen eventually. The Fe(+0) can't react with either the Na or teh Ga. Sooner or later the iron content would be so great that...the Fe would preciptate out? Would the solution eventually turn into solid Fe intemixed with Na and Ga?

    What about this question: What if there were a perfect vacuum within a volume. And Fe(+0) atoms were injected in this volume. As the Fe contined to increase, wouldn't the Fe atoms eventually bond into solid Fe? Or, would that only happen under heat and pressure? Do metals have no affinity to combine into a solid state unless compressed or otherwise forced to do so?

    Thanks
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  9. #8 wtaer treatment 
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    while researching water treatment i found this post and learn from it so since osmisis was not covered here i thought i would mention it
    i have no science training so i cant hit you with math or figures facts or forums but it seems like you are looking for a path for pure water as am i
    so simply put i think osmises may be the path of least resistance that said si-fi changes everything and continues to prove us wrong with such style dont get caught up in what you see in the box si-fi is about whats outside the box cut your own path leave the relm of possiblility let science catch up with you not the other way around and good luck may your vision be a game changer
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  10. #9  
    Bullshit Intolerant PhDemon's Avatar
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    Gibberish, your post adds nothing but nonsense...
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  11. #10  
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    Now it is out there, i want to throw in my 2 cents.

    Iron is very peristent, and usually the only way to get all the iron out of a solution is chelation or boiling and recapturing the water.

    EDTA will inactivate the iron, but it won't get it out of the solution. Oxygen can and will form Fe2O3, but only up to a degree where the Fe2O3 will redissolve in the water and form some sort of balance. Next solution would be to suspend it with phosphate, however this wouldn't get it all out of the solution. Reverse osmosis would be a possibility, and it would get you the same results as boiling it. Albeit it will take less energy.

    Anyway,
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  12. #11  
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    The easiest way I can think of is to add a small amount of sodium hydroxide to the water, the iron will precipitate out as iron (III) hydroxide which can be filtered off.
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