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Speculation on pickle renewal


#1

If spent pickle is loaded with copper ions (?). Would it not be
possible to renew the mix by removing the copper through plating a
piece of sacrificial copper? If I soaked a piece of copper wrapped in
steel wire would that renew the pickle?

I work with copper and use a vinegar and salt pickle solution.
Wouldn’t the same work for Sparex?

I’m doing a test now and the green colour is reduced but there seems
to be a cloudy deposit that is forming. I will try to filter it out,
and then test my “cleaned” solution.

RRuff


#2
If spent pickle is loaded with copper ions (?). Would it not be
possible to renew the mix by removing the copper through plating a
piece of sacrificial copper 

I can’t say with any certainty, but my understanding is that the
copper plates out because the solution gives up the copper in favor
of the iron. So the pickle isn’t renewed, it is just less saturated
with copper, and more saturated with iron. Maybe one of our resident
chemists can verify/debunk this, and of course, you can try it and
see what happens.

–Noel


#3

In addition to Noel’s commnet;

In case of sulfuric acid pickle, the chemical reaction is, copper +
sulfuric acid -> copper sulfate + hydrogen.

Copper sulfate gives blue color to the solution, and hydrogen is gas
that escapes away from the solution. Because hydrogen ions (acid) are
gradually lost in gas form upon the reaction, used pickle not only
accumulates copper ions but also contains less hydrogen ions.

Akiko