Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "dl5012" <dl5012@...> wrote:
>
> Hi,
> 
> Glad you rang in on this topic...
> 
> What is the proper way to dispose of used ferric chloride?  Is there 
> a way to rejuvinate it?  Someone mentioned adding sulfuric acid, but 
> everyone is imprecise about ratios.  

No, not Sulfuric Acid; use Hydrochloric Acid instead.  As for how
much, the appropriate amount is some.  

> Is there a simple way to 
> determine how much life is left in the etching solution?  

When it starts taking too long to etch, there's not enough life
left.

> Is there 
> an inexpensive way to precipitate the copper out of the solution and 
> end up with just ferric chloride?

I once tried electroplating out the Copper (Carbon cathode, Iron
anode).  It sort of kind of worked (I ended up with Copper crystals 
on the cathode.), but I don't remember if the resulting solution 
was any good for etching or not (or, whether I even tried it).  My
intent was to remove the Copper and replace it with something less
biologically nasty than Copper.  Maybe if we have an electro-chemist 
in the house, he can advise on such a procedure (Beware of 
outgassing Chlorine gas if you try such a procedure!).

> I'm hesitant to use some of the other recipes.  I've used ferric 
> chloride for many years and my main concern was not breathing the 
> chlorine gas that gets released.  Now, that I'm more environmentally 
> aware, I want to know how to dispose of it properly.  An old bottle 
> I had from Radio Shack said to put it down the toilet.  I'm sure 
> that's not a good thing to do these days...

Actually, Ferric Chloride isn't that bad (It's been used as a 
nutritional supplement in it's food grade form.).  Unfortunately, 
used solution has a lot of Copper Chloride in it, which is deadly 
to most biological organisms.

> Regards,
> Dennis

Dave