In my opinion:
H2O2 doesn't stay H2O2 for long. It is likely mostly H2O by the time it
reaches the sewer plant.
HCl? As you say, not a huge problem, it tends to lower pH, which may be
precisely what the sewer plant wants and I'd not be surprised if they
didn't use the stuff themselves.
The worst thing in the effluent from etching may well be CuCl, which is
pretty toxic to crustacea, snails and perhaps (guessing) bacteria, which
is why some folks neutralize it with NsOH (Drano) before dumping it.
Of all the things you could poor down your drain, HCl is likely the most
innocuous.
On 06/12/2010 02:38 AM, Slavko Kocjancic wrote:
> Disposal note...
>
> I had to say we are wery 'eco friendly'.
> I etch my board with Hcl and H2O2. For 10x10cm board I use aprox 5ml of
> H2O(tap water), 1ml of HCl(30%) and 1ml of H2O2(30%).
>
> So aprox 2 to 3 years I need to buy new bootle (1 liter) of both.
>
> Now look to disposal problem.
>
> The average household drain HCl in sinks/toilets as cleaner(near all
> cleaner use HCl) in amount much larger that mine is. The quantity is so
> smal so if someone throu up (maybe to much beer) the HCl pollution is
> bigger. So I don't care and throw that into sink. The other content
> H2O2. You may look in two sides. The all hair paint use H2O2 in large
> quantity and throw that stuff into sink directly. Every unnatural
> blondie use much more H2O2 than I. In the other way if we let H2O2 on
> sun few day they completly disentigrate into H2O and O2. So I can say
> that source chemical used is so small that we can just sink em. ..and
> use a loot of watter to dilute it. The worst contaminant is byproduct
> CuCl. And again. The content is so small and we can throw it. The
> average wineagre yard near me use so much CuCl so my quantity is way way
> lower. And someone will say that all that sink output goes into sea.
> CuCl is extensively used to paint boat's to prevent algae sticking on it.
>
>
> But if you think that we must be the 1'st one to preserve planet then
> you have simple solution how you can dispose the used solution.
> Just get one glass jar as low and flat as you can. Put it onto sun and
> pour all chemicals used from pcb etchng into it. Then cover it with
> glass plate little raised. So all thing will evaporate on sun and leave
> the worst (CuCl) as little blue/green sand. When you collect much of
> that than just dispose that in chemichal dispossing containers. But for
> 100grams you need to etch a lot of boards.(years)
>
> ...But this work's just if you use smallest quantity possible. I see a
> lot of folks use just to much etchant. If you check youtube you can see
> that a lot of users use so big quantity of etchant. So the key is smal
> quantity and smal bath. I use the plastic kontainers for food / ice
> cream. It should have flat bottom and be just right size. (I have 4
> different size) So just use smalest one and use as little etchant as I
> can. ..just to cover the PCB not more. And etch it outside with wind
> blowing in you back. When etching the small content of chlorine gas is
> developed. You don't want to breath that. The etching time is 2 to 3
> minute. And use cold watter. As reaction is exotermic (release heat) the
> solution wil heat up itself. If you use hot watter in start the solution
> will boil when etching and that exesive heat may destroy your image etched.
>
> Thanks for reading and sorry for my ugly english.
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>
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