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Iron-oxide (rust) making question

  1. Apr 22, 2006 #1
    Well Im trying this electrosys method and this is how I have it set up:

    The battery is connected to the salt water via two wires, the negitive wire leading and attached to the steel wool, and the postive wire is just in the water, not touching the other things.

    After awhile it separates, the rust (I think) is on the top, it is orange. Then at the bottom there is some black stuff. I have no idea what that is and if it is soposed to be there. If you could explain it would be a great help!

    Also Im wondering if someone could explain how to take out the rust and dry it.

    Any help would be VERY appriciated!

  2. jcsd
  3. Apr 22, 2006 #2


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    I think you have your cell reversed, you should place the steel wool at the anode (+) not the cathode (-).
    Oxidation takes place at the anode which will cause the Iron to loose electrons and become Fe+2.

    The black stuff could potentially be impurities in the steel wool which are being released as the Iron reacts away. Since Steel is an alloy of Iron and Carbon, if the Iron is dissolves away, the Carbon would be left behind unreacted, possibly in a black powdery graphite form, and would settle to the bottom.

    Once you have reacted all the Iron and you are ready to extract the rust, decant off as much water as you can, then dry the rust in the hot sun. As the rust is drying, the heat will convert any Iron Hydroxide remaining into Iron Oxide and water (the water will then evaporate). You should be left with a reddish-brown Iron (III) Oxide.
  4. Apr 22, 2006 #3
    Hmm, about the cells. All the tutorials I have read on this say to put it on the positive! And if I did switch it around, what would happen differntly?

    Now about the black stuff, would I just poor out the water till I start getting the black stuff and separate the rust and the water from there?

    EDIT: Also, I tried switching the cells a few days ago (the iron on the postive not negitive, but I used a nail, not steel wool).. And I used a nail, left it over night and was left with merky water and red stuff on the bottum. But I started to think the stuff I made was Copper Oxide because O noticed the stripped end of one of the wires in the water deteriorated, and there was no noticable deterioration to the nail. If you could explain, It would be a big help.

    Also, If I do indeed switch the cells around, when ready, could I just poor all the red stuff down to the top off the black in a pot and boil it water till it evaporates, leaving just the powder for me to grind?
    Last edited: Apr 22, 2006
  5. Apr 22, 2006 #4


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    It sounds as if, from your description, you havr the negative wire connected to the steel wool, making the steel wool act as the cathode.
    Is that not what I said?

    If you switch the polarity on the electrodes, you will be oxidizing the wire and not the steel wool, meaning you will probably be putting Copper Ions into solution (assuming of course you used Copper wire).

    Do both the black and orange powders both settle to the bottom (with the orange powder on top of the black)? If so, it will be somewhat difficult to seperate these powders?
    About how much black powder is there (compared to orange)?

    You could boil off the water if you want, that would work too, but would requite a lot more energy, the sun is free (it might not yet be good weather to do this for you yet though).

    How big of a battery are you using?
    What electrolyte are you using? Sodium Chloride (NaCl)?
    Last edited: Apr 22, 2006
  6. Apr 22, 2006 #5
    There may be some orange powder at the bottom, but im not sure. Its orange on the top, merky middle, black bottom for all I can see. And Id rather not go through the trouble of separating the bottom so should I just rid of it?

    What I do is I pour the water to the top of the black stuff into a pot, and set it on a eleletric "Hot Plate" to boil it.

    Im using one of the large "Heavy Duty" 6 volt batteries.
    And Yes, I am using sodium chloride.

    Sorry about the negitive/positive mix up, I had typed it wrong in the begining.
  7. Apr 22, 2006 #6
    I would suggest using a car battery or some other power supply if you want decent yields.
  8. Apr 24, 2006 #7


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    By the way, how commited are you to producing rust electrolytically?
    There are easier ways, believe you me, I know.
  9. Sep 7, 2007 #8
    what are the easier ways?
  10. Sep 7, 2007 #9
    I agree there are much easier ways that will produce higher yeilds in shorter amounts of time with out a power supply.
    The black stuff is maybe iron(III) oxide. Preform a simple magnetism test on it, if it is not magnetic it could be carbon or unhydrated copper oxide (a rare thing to exist in water). Steel has carbon in it, among other things. Hydrated copper oxide or copper hydroxide is greenish blue and copper compounds turn flames bluish green while iron compounds make the flame yellowish orange. If you preform a flame test i suggest you wash the material to be tested throughly as even a small amount of sodium impurity can turn the flame yellow and possibly give a false result. Some copper oxides are red, but that would be determened in the flame test.
  11. Sep 7, 2007 #10
    Just curios jhony did you happen to get the instructions from the cookbook, because if you did you know its a load of crap right? Just a warning. But it is possible to make good amounts of rust with a decent power supply. You have to connect the positive lead to what ever you want to turn to rust since oxygen is evolved from the anode. You can also make rust by dissolving steel wool in HCL then adding Potassium Hydroxide. Be careful this procedure is exothermic.
  12. Sep 7, 2007 #11


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    This will, in fact, produce Iron Hydroxide directly and not Iron Oxide, unless of course the heat released by the reaction is sufficient to decompose the Iron Hydroxide into Iron Oxide and water. If not, one can always decompose the Iron Hydroxide into Iron Oxide by heating it in an oven for a while.

    But a simpler method exists.
    Iron metal is quite readily oxidized by Sodium Hypochlorite (AKA, "bleach"). One can oxidize steel wool very effectively into Iron(III) Oxide using ordinary Clorox bleach (contains 6% NaOCl by weight). After which, all one need do is extract the Fe2O3 by the NaCl solution which is left over and dry it out.
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