[Noisebridge-discuss] [Fwd: Re: gEDA-user: Disposing of Etch Solution]

jim jim at systemateka.com
Thu Jan 20 09:02:34 PST 2011


(as seen on the gEDA mailing list) 

----------------------------------------

Do you mean muriatic acid and hydrogen peroxide?  Those are not
hazardous chemicals if they are neutralized.  

The hydrogen peroxide is easy to neutralize; 
just put a piece of charcoal in the bottle and it should decompose.  
Exposing it to sunlight will also work.

Muriatic acid could be harder, depending on the concentration.  You
just need to react it with base.  Sodium bicarbonate, ammonia, and
powdered drain cleaner are all readily available bases.  But if the
acid is highly concentrated, you will need to mix carefully because
the reaction is exothermic.  First pour water into a container, then
mix in a calculated amount of base, then slowly pour in the acid.  I
don't know the relevant environmental regs, but I'm sure that at pH
5-9 those chemicals should be safe for any sewer.

Are the muriatic acid and H2O2 already mixed together?  I don't think
that H2O2 has an adverse reaction with most bases.  NaOH will probably
just catalyze its decomposition.  But IANAC (I am not a chemist).


---previous email--- 
>   I have excess muratic acid/hydrogen per oxcide etch solution after
>   making a board.  What is an acceptable way to dispose of it?
>
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