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How do I dispose of used Ferric Chloride etchant?

  1. Dec 10, 2017 #1
    Hi everybody.
    I'm an electronics hobbyist and use Ferric chloride to etch copper circuit boards. I'm left with a solution of copper chloride (or is it cupric chloride? Chemistry isn't my forte).
    So my question is, how do I dispose of it? I already searched around on the internet and there was no clear answer except "contact the authorities", but I can't do that here because I live in a third world dump and the authorities are not to be trusted with waste disposal. I have to do everything myself, if possible.
    I know some people who etch boards like this in large scale (a thousand boards a month or so) and these guys just throw the stuff wherever they can. One of them recently contacted me about disposal because he was worried about any damage he may be doing, which prompted my search.
     
  2. jcsd
  3. Dec 11, 2017 #2

    Baluncore

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    There is not much weight of copper in the solution, so it is probably uneconomic to refine into metallic Cu. Placing Al metal cans in a Cu solution will sometimes produce metallic Cu.

    The chlorine is a problem as it digests wood and rusts steel, so maybe you can react the waste solution to produce CuSO4. That can be used to plate metals with copper, or to treat timber to stop it rotting.

    Some soils are short of Cu as a trace element. You could treat those soils by adding a Cu compound to a fertiliser. What are your soils like?

    Cu is used in anti-fouling paint on boat hulls, while molluscs use two Cu atoms to make their blue blood = haemocyanin, instead of the Fe that makes animals blood red = haemoglobin. Green trees use an Mg atom to make chlorophyll.

    Have you thought of breeding and farming octopuses?
     
  4. Apr 5, 2018 #3

    CWatters

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  5. Apr 7, 2018 #4

    Astronuc

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    One company recommends adding sodium carbonate and/or sodium hydroxide to the ferric chloride. Copper and iron would be precipitated and the NaCl (table salt) would be in solution.
    https://www.mgchemicals.com/products/prototyping-and-circuit-repair/prototyping/ferric-chloride-415
     
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