how to dispose of CuCl2 ?

[CaptainPeyote]

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?

[elementcollector1]

The easy solution: add aluminum foil. It'll fizz a lot if there's still some HCl in there, but eventually copper metal will start precipitating. Copper metal can then be filtered out and kept as a cool souvenir, or disposed of. It should be about as dangerous as a wire (although who knows with powder?).

[CaptainPeyote]

ok great! so what's left behind then, after the aluminum is dissolved and the copper precipitates?

[John Cuthber]

ok great! so what's left behind then, after the aluminum is dissolved and the copper precipitates?

A solution of aluminium chloride and its hydrates. Probably similar in nature (if not concentration) to the stuff in many deodorants.

 

Another alternative would be to precipitate copper carbonate from the original solution with washing soda, give it a good wash with water , redissolve it in sulphuric acid, crystallise it out, mix it with lime and sell it to the organic food lobby to spray on corps as a fungicide.

 

http://en.wikipedia.org/wiki/Bordeaux_mixture

 

OK, I don't imagine you are really going to do that, but the use of copper based biocides puts the issue in context.

If you just flush the stuff down the drains with lots of water it's not going to do much harm.

 

[

Edited October 15, 2012 by John Cuthber

[CaptainPeyote]

Awesome, thanks for the great info guys!

[weiming1998]

Apart from precipitating the Cu2+ as elemental copper by single displacement with Al, CuCl2 can be reacted with NaOH to form Cu(OH)2, which quickly dehydrates to CuO, a black, insoluble powder. Reacting CuCl2 with baking soda produces a green-blue precipitate of Cu (II) basic carbonate. Both of these are insoluble in water, and shouldn't dissolve that easily, thus being less harmful to the environment. You can also keep it as a curiosity.

 

Another way to dispose CuCl2 is to simply not dispose it at all, but evaporate the solution. You will obtain green crystals of CuCl2.2H2O. Next time you want to etch, dissolve some of it in water, and add it to HCl to make an etching solution, which means you don't have to buy H2O2, as the CuCl2 now does the etching.

 

Edit: The Cu (II) basic carbonate is the green precipitate you were talking about before from reacting baking soda and HCl. I'm not sure if it's hazardous (pretty sure it's not) but you can convert the green sludge to a black, crumbly powder of Copper (II) oxide via heating the dry/partially dry sludge to about 200 degrees Celsius. This copper oxide can be either disposed (copper salts by itself is used in some household products, and rendering copper salts insoluble only serves to decrease its environmental dangers) , kept, converted to other useful forms (like CuSO4) or sold on eBay or a similar site (Copper (II) oxide is widely used as a lab reagent and as an alternative oxidizer in thermite).

Edited October 17, 2012 by weiming1998

[pippo]

If your copper chloride is soluble (either in H2O or dil acid), you can use it sparingly, though, on tree roots you might have that are nuisance (old drain pipes that are cracked, allowing roots to migrate in/grow into, etc). Home Depot sells Cu SO4 for same purpose, so your copper should do the same effect on tree roots, I think. Maybe a forester /botanist could verify this.

[CaptainPeyote]

thanks for chiming in, folks! I was hoping I'd come to the right place.

[dellr007]

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?

 

You can try the same thing i tried. 20 years ago, i dumped a gallon of feric cloride solution outside on the ground. the end result was the ground becoming a complete wasteland for 10 years and THEN only weeds came in for the next 5 years until grasses started to come back. You can treat this as a good case of long term herbicides. it even got rid of that dreaded rose fungus that's always been in the ground right there. it may not be approved by the government but now they cannot even detect it's been done and the rain/snow deposited an inch of extra soil on top of what's already been there.

 

as far as etching aluminum, try the chemical "phosphoric acid". we use that at work to etch and clean all metals but have to be careful around aluminum and pot metals because it tends to completely dissolve them if left too long. yes, that too has a herbicidal effect, especially on poison ivy.

[Hsaman]

The easy solution: add aluminum foil. It'll fizz a lot if there's still some HCl in there, but eventually copper metal will start precipitating. Copper metal can then be filtered out and kept as a cool souvenir, or disposed of. It should be about as dangerous as a wire (although who knows with powder?).

 

Hi y'all,

 

 

I have tried the aluminum process of reclaiming the copper and it works! I was wondering if anyone knows how the copper might be reclaimed on a commercial scale - several tons or more of waste that is.

 

Thanks