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Author: Subject: Disposal of Cobalt(II) Chloride
Trevor9424
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[*] posted on 23-5-2016 at 13:36
Disposal of Cobalt(II) Chloride


I have about 15 grams of cobalt chloride hexahydrate that I would like to know how to dispose of. Referring to a MSDS, it says that it should be disposed of by a hazardous waste company.

However, I've been trying to find a way to change the cobalt chloride into a different chloride salt, such as zinc or iron chloride which is less hazardous, and cobalt metal for keeping. I don't want to contact a waste company because all I have is 15 grams of it and since I'm a hobbyist, I think that would be too expensive :( . I tried two different ways so far:

1)Adding aluminium foil to a solution of cobalt chloride and then heating it (nothing happens if you just add aluminium). This caused the solution to boil a bit and turn to a cloudy grey (Aluminium Chloride?) with a black coating on the aluminium foil (cobalt?).

2)Electrolysis: Hasn't been very efficient and has only produced a tiny little ball and little change to the color of the solution. I was using a D-cell battery, copper wire, and a copper electrode for this with the wire forming a tiny ball of cobalt. Should I be using a different electrode such as zinc or carbon since copper is less reactive than cobalt?

Does anyone have any ideas for this? Thank you!

[Edit]
However, if there isn't a way to turn the cobalt chloride into a different, less harmful chloride salt and cobalt metal, I'll create a waste container for cobalt waste and once I've used up all the cobalt chloride, call a waste disposal company.

By the way, the black metal I got from heating aluminium foil in cobalt chloride solution didn't seem magnetic which put me in doubt that it was cobalt (the magnet was a door magnet for a shelf).

[Edit #2]
Also, is it safe to throw cobalt metal or its water-insoluble compounds away as long as they're done so in a container? The MSDS I referred to says cobalt metal can be thrown away (though it is still potentially carcinogenic) and I thought that since it would no longer be soluble in water like its chloride salt, it would be much less hazardous.

[Edited on 5-23-2016 by Trevor9424]

[Edited on 5-24-2016 by Trevor9424]
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[*] posted on 23-5-2016 at 15:43


Quote: Originally posted by Trevor9424  

1)Adding aluminium foil to a solution of cobalt chloride and then heating it (nothing happens if you just add aluminium). This caused the solution to boil a bit and turn to a cloudy grey (Aluminium Chloride?) with a black coating on the aluminium foil (cobalt?).


I wonder if that black coating is cobalt(II) aluminate:

(from Wikipedia)
"Its compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes."

I know that when I was in ceramics class we used a black Cobalt compound that made a deep blue when painted on our pots, overcoated with glaze and fired. I don't know which compound it was, but these descriptions sure all fit together well.
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[*] posted on 23-5-2016 at 15:47


The cloudy grey is bits of aluminum hydroxide and bits of silicon from the aluminum not being 100% pure. The black coating was probably cobalt metal.

Cobalt aluminate is blue, not black, and only forms in very basic solution. The black compound you used in ceramics was probably the oxide, which would dissolve in glass to give deep blue.




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[*] posted on 23-5-2016 at 15:53


Here's a picture of the black (it's more grey now) substance left on the aluminium. It likely does have some aluminium left in it which may be the white/shiny specks.

IMG_7266.JPG - 2.4MB
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[*] posted on 23-5-2016 at 15:54


Another picture: (Sorry that it is a bit blurry)

IMG_7267.JPG - 1.6MB
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[*] posted on 23-5-2016 at 15:59


See if it's magnetic.



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[*] posted on 23-5-2016 at 16:02


Quote: Originally posted by DraconicAcid  
The cloudy grey is bits of aluminum hydroxide and bits of silicon from the aluminum not being 100% pure. The black coating was probably cobalt metal.

Cobalt aluminate is blue, not black, and only forms in very basic solution. The black compound you used in ceramics was probably the oxide, which would dissolve in glass to give deep blue.


Ahh, that would explain why Wiki said the aluminate can be used in inks and paints.
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[*] posted on 23-5-2016 at 16:07


Quote: Originally posted by DraconicAcid  
See if it's magnetic.


Above, I did say it was not magnetic (but it was in a glass vial). I tried again outside of its container and it stuck to the magnet :) . I now have cobalt dust permanently stuck on the door magnet on my shelf.
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[*] posted on 23-5-2016 at 16:09


If the cobalt chloride is reasonably pure, you might be able to sell it to someone.
For electrolysis, I would use more than a D-cell battery. If you have 15 grams, you have 0.063 moles of cobalt(ii), which will take 1.2*103 C of charge, or 3.4 Ah, to reduce to the metal. A D-battery would take a while to provide this, and might run out before it could.

[Edited on 5-24-2016 by Metacelsus]




As below, so above.

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[*] posted on 23-5-2016 at 16:16


Quote: Originally posted by Metacelsus  

For electrolysis, I would use more than a D-cell battery. If you have 15 grams, you have 0.063 moles of cobalt(ii), which will take 1.2*103 C of charge, or 3.4 Ah, to reduce to the metal. An alkaline D-cell battery has less than 2 Ah.


So using about 3 to 4 D-cell batteries would help complete the electrolysis? I was also using only copper cathodes and anodes during the electrolysis, the copper electrode that reduced the cobalt was a thin wire (In which the end of it is likely completely oxidized by now). Would using something more reactive than cobalt, such as zinc, be more effective or would it not make a difference?
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[*] posted on 23-5-2016 at 19:27


I'd keep the cobalt chloride. Or give it to someone. It is nice stuff to have.



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[*] posted on 24-5-2016 at 17:14


As it is, an insoluble cobalt-aluminum compound which is attracted to a magnet is definitely worth keeping.



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[*] posted on 31-5-2016 at 11:02


Just add Na2CO3 (or NaOH) to form an insoluble carbonate (or hydroxide).

Or, more for the purpose of experimenting, try the following inexpensive, but not particularly fast route. Dilute your CoCl2 and place in an open shallow dish (even better use a fish's tank air pump) in strong sunlight with a small amount of ascorbic or citric acid (from say lemon juice) with NaCl and apply heat.

If you get a precipitate, the reaction is paralleling the transition metal copper, which may form an insoluble cuprous or basic cupric salt under these conditions.

How the experiment works: Apparently, both Copper and Cobalt salts in their lower valent states can react directly with dioxygen with a source of H+. The acids and sunlight also serve as reducers to achieve the lower valent state and the NaCl to increase the solubility of the cuprous (by forming a complex), in the case of copper, to move the reaction along towards the formation of the basic salt.

For more details including references, see my comments in a recent thread at http://www.sciencemadness.org/talk/viewthread.php?tid=66247#...

[Edited on 1-6-2016 by AJKOER]
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[*] posted on 5-6-2016 at 06:24


Quote: Originally posted by Trevor9424  
I have about 15 grams of cobalt chloride hexahydrate that I would like to know how to dispose of. Referring to a MSDS, it says that it should be disposed of by a hazardous waste company.

However, I've been trying to find a way to change the cobalt chloride into a different chloride salt, such as zinc or iron chloride which is less hazardous, and cobalt metal for keeping. I don't want to contact a waste company because all I have is 15 grams of it and since I'm a hobbyist, I think that would be too expensive :( . I tried two different ways so far:

1)Adding aluminium foil to a solution of cobalt chloride and then heating it (nothing happens if you just add aluminium). This caused the solution to boil a bit and turn to a cloudy grey (Aluminium Chloride?) with a black coating on the aluminium foil (cobalt?).

2)Electrolysis: Hasn't been very efficient and has only produced a tiny little ball and little change to the color of the solution. I was using a D-cell battery, copper wire, and a copper electrode for this with the wire forming a tiny ball of cobalt. Should I be using a different electrode such as zinc or carbon since copper is less reactive than cobalt?

Does anyone have any ideas for this? Thank you!

[Edit]
However, if there isn't a way to turn the cobalt chloride into a different, less harmful chloride salt and cobalt metal, I'll create a waste container for cobalt waste and once I've used up all the cobalt chloride, call a waste disposal company.

By the way, the black metal I got from heating aluminium foil in cobalt chloride solution didn't seem magnetic which put me in doubt that it was cobalt (the magnet was a door magnet for a shelf).

[Edit #2]
Also, is it safe to throw cobalt metal or its water-insoluble compounds away as long as they're done so in a container? The MSDS I referred to says cobalt metal can be thrown away (though it is still potentially carcinogenic) and I thought that since it would no longer be soluble in water like its chloride salt, it would be much less hazardous.

[Edited on 5-23-2016 by Trevor9424]

[Edited on 5-24-2016 by Trevor9424]


Where do you live? Most townships in north america and europe offer hazardous waste disposal for households. So long as you arent getting rid of barrels of waste they should take the stuff at your local waste facility.
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[*] posted on 23-6-2016 at 05:28


Precipitate out and junk it. You can always make some Cobalt(III) Oxide with the solution and bleach. It's an insoluble black powder, so far as I remember (wikimedia has a picture of it).



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[*] posted on 23-6-2016 at 08:30


If you don't want it, send it to me. I'll pay for shipping.



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[*] posted on 23-6-2016 at 15:07


Quote: Originally posted by Praxichys  
If you don't want it, send it to me. I'll pay for shipping.


Actually, I started this thread up mainly because I wanted to try to find methods of safely disposing of cobalt chloride waste after using it, not to outright dispose or rid of all 15 grams of it I have, sorry :(. On another note, I tried adding some sodium bicarbonate to some cobalt chloride, since sodium bicarbonate tends to react with transition metal salts to form water insoluble carbonates, and a purple-pink solid fell out of solution which I filtered off leaving nearly a nearly colorless solution.
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[*] posted on 24-6-2016 at 02:37


The best way to dispose 15 grams of CoCl2 is to throw it out of the window or flush down the toilet.
Disposal of cobalt chloride would be a problem if you had 15 kilos of it, not 15 grams.

[Edited on 24-6-2016 by byko3y]
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[*] posted on 26-6-2016 at 04:50


By the way, surprisingly, you need quite an excess of bicarbonate/carbonate to precipitate all of the Cobalt(II). I found this out when making some Cobalt(II) carbonate intentionally, an finding that I needed a lot more carbonate than expected.



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[*] posted on 26-6-2016 at 06:20


Quote: Originally posted by Trevor9424  
I have about 15 grams of cobalt chloride hexahydrate that I would like to know how to dispose of. Referring to a MSDS, it says that it should be disposed of by a hazardous waste company.

However, I've been trying to find a way to change the cobalt chloride into a different chloride salt, such as zinc or iron chloride which is less hazardous, and cobalt metal for keeping. I don't want to contact a waste company because all I have is 15 grams of it and since I'm a hobbyist, I think that would be too expensive :( . I tried two different ways so far:

1)Adding aluminium foil to a solution of cobalt chloride and then heating it (nothing happens if you just add aluminium). This caused the solution to boil a bit and turn to a cloudy grey (Aluminium Chloride?) with a black coating on the aluminium foil (cobalt?).

2)Electrolysis: Hasn't been very efficient and has only produced a tiny little ball and little change to the color of the solution. I was using a D-cell battery, copper wire, and a copper electrode for this with the wire forming a tiny ball of cobalt. Should I be using a different electrode such as zinc or carbon since copper is less reactive than cobalt?

Does anyone have any ideas for this? Thank you!

[Edit]
However, if there isn't a way to turn the cobalt chloride into a different, less harmful chloride salt and cobalt metal, I'll create a waste container for cobalt waste and once I've used up all the cobalt chloride, call a waste disposal company.

By the way, the black metal I got from heating aluminium foil in cobalt chloride solution didn't seem magnetic which put me in doubt that it was cobalt (the magnet was a door magnet for a shelf).

[Edit #2]
Also, is it safe to throw cobalt metal or its water-insoluble compounds away as long as they're done so in a container? The MSDS I referred to says cobalt metal can be thrown away (though it is still potentially carcinogenic) and I thought that since it would no longer be soluble in water like its chloride salt, it would be much less hazardous.

[Edited on 5-23-2016 by Trevor9424]

[Edited on 5-24-2016 by Trevor9424]


If you live in Canada theres a good chance that your county has a program to take toxic waste from households. This may also apply to some US states. Ask your county if they take hazardous household waste.
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