Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "Dave" <wa4qal@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, February 07, 2006 8:46 PM
Subject: [Homebrew_PCBs] Re: Dangerous Chemicals


> --- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon.heller@...>
> wrote:
>>
>> ----- Original Message -----
>> From: "dl5012" <dl5012@...>
>> To: <Homebrew_PCBs@yahoogroups.com>
>> Sent: Tuesday, February 07, 2006 8:17 PM
>> Subject: [Homebrew_PCBs] Re: Dangerous Chemicals
>>
>>
>> > 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. Is there a simple way to
>> > determine how much life is left in the etching solution? Is there
>> > an inexpensive way to precipitate the copper out of the solution and
>> > end up with just ferric chloride?
>>
>> Adding H2O2 and a little HCl should convert any cuprous chloride in the
>> solution to cupric chloride, which is an etchant in its own right. Any
>> ferrous chloride would get converted back to the ferric form. I've
> tried it
>> and it seems to work.
>
> Me, too. You can find HCl, as Muratic Acid, in most hardware
> stores.
>
>> > 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...
>>
>> I just pour it down the bog!
>
> The Ferric Chloride isn't that bad of a problem. The problem is
> that used solution contains soluable Copper compounds, and these
> are lethal to most biological organisms.

The amounts will be undetectable by the time it gets to the sewage plant,
with the enorrmous dilution that will have taken place. I used to deal with
the water company where I worked a long time ago, and they used to check our
effluent regularly - I didn't know when they would be coming, though. They
used to be most concerned about chlorinated solvents (which we used a lot)
killing their bugs.

Leon