On Mon, 16 Feb 2004 06:19:24 GMT, "Carl Ijames"
wrote:


I completely agree that you have to have oxidation at the anode, I just
find it hard to belive that you will produce Cr(VI) and not Cr(III). So
far as I remember my electrochemistry courses, electrolytic dissolution
pretty much always produces the lowest stable oxidation state. I've
done a lot of electropolishing of stainless steel, and those solutions
always turn green, consistent with Cr(III). Have you chemically
verified the presence of hexavalent chromium or did you just trust the
color, which could be due to dissolved rust or other metal ions at low
concentration (no, I didn't on my solutions)?

No, I haven't run any chemical analysis. I'm not in a position where
I have to prove anything to myself. In eight years I've used a
variety of electrodes and have seen just about every color in the
solution caused by the rust being removed.

The only time I got a yellow solution is when I used stainless steel
that disinegrated as described. I've been around lots of stationary
Diesels that used chromate-treated coolant. The appearance was
exactly the same. That's good enough for me.

I have never seen a green-tinted electrolyte in my setup.

If I tell people to use stainless electrodes and they go ahead and do.
And, if they discard their electrolyte on their property, what
position does that put me into?

In this litigious society, I'm going to express every caution that I
can think of.

Orrin