[sdiy] Disposing of cupric chloride

[David G Dixon]

> It is indeed light blue. David; i'm a little confused about 
> you saying it's harmless as every other source i've found 
> says it's indeed really bad for the environment, not saying 
> you're wrong just saying that's what i've read on several 
> different blogs and sites. So is the white slime at the 
> bottom the copper salt or?

It is toxic to fish and algae.  However, you've probably got less than 10
grams of total copper in your etchant solution.  Not exactly an
environmental catastrophe.

Add a bunch of base to it, like sodium carbonate.  You will end up with
copper carbonate and salt water:

CuCl2(aq) + Na2CO3(s) --> CuCO3(s) + 2 NaCl(aq)

The solid is copper carbonate.  Filter that on a coffee filter and throw it
in the garbage, or put it in the oven to make copper oxide, or whatever,
then throw it in the garbage.  It won't releach without acid, so it's pretty
safe.  Dump the water.

Better yet: reuse the etchant.  That's the whole point of this etchant
solution.