Sergio,
Egg on my face! I etched some copper with the H2O2 and muriatic acid and=20
then precipitated out the copper with baking soda as I suggested. You=20
were right, the remaining solution is too blue (has some copper left)=20
for me to feel good about dumping down the drain, don't even need the=20
ammonia test. I'll try the steel wool to scavenge the remaining Cu.



Looking forward,
Al Shinn



Looking forward,
Al Shinn


On 1/3/2012 10:52 AM, Al Shinn wrote:
> Sergio,
> I clearly stated "hardware store muriatic acid and drugstore hydrogen
> peroxide" Should I have added "full strength"?
> There would be only the smallest traces of copper left after
> precipitating with baking soda. Copper is not like mercury or lead in
> that neither of them have a minimum daily requirement - copper does. We
> use copper pipes for our water, copper coated scrub thingeys, etc, etc.
> we used to use CuSO4 to kill roots in the sewer lines but that WAS tough
> on the sewage treatment plants.
> If you wish to remove any final traces of copper, first test some of the
> suspect clear solution with a dollop of household ammonia, any
> significant copper will turn the resulting solution blue - if the test
> fails, electrolyze out the remaining copper or even just throw in some
> steel wool to scavenge the copper out.
> What I should have mentioned is that you should not throw away the
> solution anyway cause "they" say it regenerates with exposure to air and
> can be used over and over. I don't do that much etching so I toss mine.
>
> "
> Not wishing to be a kill-joy here BUT...
>
> "two parts hydrogen peroxide for every one part hydrochloric acid"
>
> Doesn't really tell me a lot. What are the concentrations of these liquid=
s
> before you mix them?
>
> Also, mixing "baking soda" with copper chloride (the result of etching
> copper metal with HCL and H2O2) does ***NOT*** result in pure water +
> solids, there will be some copper ions left in solution. You really
> shouldn't just flush this down the drain as a mater of course.
>
> Regards
> Sergio Masci
> "
--=20
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