Hi science buffs,
First post here... seems like a cool place!
I've just started using a mixture of hydrochloric acid and hydrogen peroxide to etch printed circuit boards, as I was sick of spending big bucks on (and ruining perfectly good shirts with) dirty FeCl etchant. I'm certainly no chemist, but if I understand this correctly, copper dissolves into solution, creating a "self-regenerating" CuCl2 solution that can be refreshed by simple aeration, or by adding a bit of HCl or H2O2 every now and then. This all sounds great, but I have concerns about safe disposal. Apparently the dissolved copper is highly toxic to fish etc., so I can't just dump it down the drain.
Is there a way to make the etchant safe for disposal by adding some other readily available chemical? I'm hoping for some way to precipitate the copper or otherwise reduce the volume of hazardous waste.
I tried googling, but the best solution I could find was adding a ton of baking soda to neutralize the acid, then drying the mixture in the sun to produce some kind of green, hazardous paste that still needs special disposal. Anybody got a better idea?
The best thing would be if I can treat the solution so it becomes inert and non-toxic, and I can just flush it down the drain. But reducing the volume of hazardous waste would be just great, too.
Thanks,
Justin
p.s. - anybody know if my solution will etch aluminum alloys as well?
