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  1. #1

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    Ferric Ammonium EDTA, can I make it?

    Hi all,

    I have EDTA (Ethylenediaminetetraacetic acid disodium salt), heaps;

    I have Ammonium Ferric Sulfate

    Can't I make Ammonium Ferric EDTA out of it? Many thanks!

  2. #2
    Photo Engineer's Avatar
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    It is very difficult to remove the sodium.

    To make it you must start with the free acid of EDTA and add ammonia then add the iron salt, but then you end up with the negative ion associated with the iron and etc.

    It is made commercially from Ferric Oxide powder, Ammonia gas, water and EDTA in a high pressure and high temperature vessel.

    PE

  3. #3

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    If the pH is correct and the concentration of ammonium ion, iron 3, and EDTA is correct in the final solution, why is it important to remove the sodium?

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    The effectiveness of Ammonium Ferric EDTA is diminished in both bleach and blix baths by the presence of sodium Ion.

    In any event, the question was about making the ammonium salt, not the sodium salt which is what would form otherwise. You would get Disodium ammonium Ferric EDTA AAMOF, which is not very active compared to the ammonium salt sold as an ~60% solution.

    That particular method, adding disodium EDTA to Ferric Ammonium Chloride or Sulfate was how I made the first blix for Kodak. We improved it mainly through elimination of sodium.

    PE

  5. #5

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    PE, Is that possible to substitute Ferric Ammonium EDTA with {Ethylenediaminetetraacetic acid diammonium copper} or {Ethylenediaminetetraacetic acid diammonium salt} for use in C41 bleach action? I can get this from fluka.

    Thanks!

  6. #6
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    The copper probably will not work. The Ammonium EDTA + Ferric Chloride in proper molar ratios + 10% excess of Ammonium EDTA will make a pretty good bleach when adjusted to pH 6.5. This is what I used initially before the startup of the EK plant making Ferric Ammonium EDTA directly.

    1 mole of Ferric Chloride + 1.1 moles of Ammonium EDTA should do the job. Adjust pH with Acetic Acit 28% and Ammonium Hydroxide solution as needed.

    PE

  7. #7

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    I actually have some Ferric Ammonium EDTA as part of a two part bleach-fix for a commercial dip and dunk machine, but what could it be used for by itself? How would it react to B&W films/papers?


    Quote Originally Posted by Photo Engineer View Post
    It is very difficult to remove the sodium.

    To make it you must start with the free acid of EDTA and add ammonia then add the iron salt, but then you end up with the negative ion associated with the iron and etc.

    It is made commercially from Ferric Oxide powder, Ammonia gas, water and EDTA in a high pressure and high temperature vessel.

    PE



 

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