(rec.pyro) Making copper oxychloride



Thought I'd throw this out here:

Copper oxychloride, better called copper hydroxychloride or basic copper
chloride, Cu(OH,Cl)2, is generally made by neutralizing a strong solution
of copper chloride. The process is simple and needs very little attention.
If you have a chemical bent like I do, you may be interested in making your
own.

Place scrap copper metal into a plastic bucket. Bare copper wire and strap
is ideal. If it's enamelled or insulated, burn it off first with a torch.
(Beware the fumes if the insulation is PVC. It's better to strip PVC
instead.) Cover with 15% hydrochloric acid. (Muriatic acid, found at the
hardware store, is 31.45%. Dilute 50% with water.) The solution will
immediately turn green, as some copper dissolves in the acid. Since copper
is a noble metal, it will not dissolve very quickly. The trick is to
expose the solution to oxygen, oxidizing the copper and bringing it into
solution. An aquarium bubbler will speed this process. (Be sure to use
plastic parts, which won't react with the string acid! A submerged pump
motor will probably not last long.)

Over time, the solution will become deep green or brown and much of the
copper will have dissolved. At this point, you have a strong solution of
copper chloride. You are ready to make the oxychloride.
You can also start with copper chloride (usually CuCl2.2H2O, a light blue
salt) dissolved in water at this point.

I). By neutralization:
Remove the remaining metal from the corroding bucket and bubble air until
the solution is a bright green color. Add a base, such as sodium hydroxide
(dissolve in water first), carbonate or bicarbonate, to the nearly-neutral
copper chloride solution. I recommend sodium bicarbonate, a mild base.
Neutralize in a large bucket because a lot of foam will be produced.
Pastel green copper oxychloride will precipitate. Wash and dry the
product. Caution: sodium hydroxide is a strong base and, if you add too
much, may strip chloride from the product.

This product should be stable in boiling water, whereas pastel blue copper
hydroxide will decompose to black copper oxide. Copper hydroxide is
produced when a solution of copper with little chloride (a dilute copper
chloride solution, or any strength of copper sulfate or nitrate) is
neutralized.

II). By oxidation:
Continue bubbling the solution over copper metal. The metal will continue
to corrode, while as the solution oxidizes, it will produce copper
oxychloride. After some time, stir up the suspension, strain out the
metal, continue bubbling the solution and let the copper oxychloride
settle. Collect the precipitate, wash it repeatedly with water, then dry.
The rinse water will contain dilute copper chloride which can be
concentrated by evaporation and returned to the corroding bucket.

You can continue the corrosion process until the solution has almost no
copper left in it. At this point, you can add acid and start back at the
beginning.

A bubbler is not necessary, but the process is very slow without. The
pound of copper oxychloride I recently advertized (which has been claimed,
thanks!) took months to form, in a milk jug sized bucket. But what can I
say, I just love copper so much that I love to torture it with a long soak
in acid. ;-)

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms


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