Sciencemadness Discussion Board

Nickel Oxide Hydroxide (Peroxide) from Copper/Nickel alloys

tupence_hapeny - 7-4-2007 at 04:11

Preparation of Copper and Nickel Salts

The silver coins* in use in the majority of countries consist of an alloy of copper & nickel (in Australia the 5c, 10c, 20c & 50c coins are 25% nickel & 75% copper). These coins when dissolved in ~30% Hydrochloric acid will give Copper (II) Chloride (CuCl2) and Nickel (II) Chloride (NiCl2) in a 3:1 ratio. Unfortunately both of these salts are water soluble, and must be separated by more laborious means (such as by taking advantage of the fact that Nickel salts are paramagnetic).


However, there is an easier way. The copper (II) chloride can be reduced to give cuprous (I) chloride, either by heating the mixture to ~1,000C or by treatment with sulphur dioxide (SO2). The best procedure for doing so (which will not effect the nickel (II) chloride), is to use sodium bisulfite or sodium metabisulfite and hydrochloric acid to generate the sulphur dioxide in situ. The cuprous (I) chloride will precipitate as an insoluble white salt, and can be removed by filtration (after filtration, neutralize the solution with bicarbonate). Upon standing for any time, this salt will oxidize in air to give Copper (II) Chloride.


The nickel (II) chloride is now dissolved in a solution containing sodium chloride. In order to purify the nickel it will be necessary to convert it to its hydroxide (which is insoluble) or to its peroxide (also insoluble). The hydroxide salt is precipitated by use of either calcium or sodium hydroxide, while the peroxide (actually nickel oxide hydroxide) is prepared via either calcium or sodium hypochlorite and is a dark precipitate.


The pertinent details of each of the salts is here:


http://en.wikipedia.org/wiki/Copper%28I%29_chloride

http://en.wikipedia.org/wiki/Copper(II)_chloride

http://en.wikipedia.org/wiki/Nickel(II)_chloride

http://en.wikipedia.org/wiki/Nickel%28II%29_hydroxide

http://en.wikipedia.org/wiki/Nickel%28III%29_oxide-hydroxide


Anyhow, these salts are of some interest to amateur chemists, the nickel (III) peroxide is useful for converting aldehydes to their acid, while copper (I) & (II) chloride are both mild oxidants. The purified nickel hydroxide can be converted to its halo-salts by simply reacting it with the relevant acids, and as such the nickel (II) chloride (as purified) can be used in both oxidation and reduction reactions, the first as a catalyst with hypochlorite and the second as a couple with Zinc

* I chose to design a reaction from coins, simply because they are available and they contain a known ratio of nickel and copper (3:1 or 75:25). I assume that any nickel/copper alloy would work equally well, however, if the alloy contains other metals – the resultant salts will need to be worked through.

NB The destruction of legal tender is a federal offence, please take note of this fact and do not actually use coins in this reaction (although if some other countries coins – NZ, etc) are used this is not an offence.

Also note, I have not carried this out, as I have yet to be in a position where I have the time or effort to do so. I think it might work, although I certainly haven't taken the effects of the two metals upon each other into account.

If that will make the above act differently, please tell me how and why?


[Edited on 7-4-2007 by tupence_hapeny]

not_important - 7-4-2007 at 07:35

NiSO4 is more thermally stable than CuSO4, heating to 700 C or so give NiSO4 + CuO + SO3


It may be possible to plate from the coins, using free acid electrolyte, plating out the copper and leaving nickel in solution.

[Edited on 7-4-2007 by not_important]

Klute - 7-4-2007 at 09:27

I'm really not sure Cu metal disslove in HCl that easy... if it even does, it would take days... That's why HNO3 is use to dissolve Cu metal in a hour or so... even H2SO4 is pretty long and uneffective in my experience... Converting the nitrate salts to the hydroxides/oxides (for Cu), than to the sulfates and finnaly heating at 700°c as not_important suggests would be a viable option...

Even if there is some good info , Wikipedia shouldn't be your only source of info, often alot of things are missing, and the info isn't always reliable.. just some advice..

Levi - 7-4-2007 at 10:33

Cu will dissolve in a solution of heated HCl with the gradual addition of some H<sub>2</sub>O<sub>2</sub>, but you're correct, Klute, it is painfully slow if you don't babysit the reaction so you can make sure it's staying warm and continue to add the peroxide.
I personally like not_important's suggestion of plating out the copper, though. Someone should definitely try this and post the results.

tupence_hapeny - 7-4-2007 at 16:17

Not interested in fast, I am just sitting here not seeing a fine white salt starting to precipitate out of a light green solution (after about 12 hours). The coins that aren't in there are still not in there, although if they were there they may have changed colour to a more goldlike hue. Not having had ANY experience of metallic chemistry for decades, I find it somewhat amusing... (that is of course, if it were happening).

tup

guy - 7-4-2007 at 22:05

I'm having a nightmare trying to dissolve some US nickel coins. It takes forever! Im using sulfuric acid and it still slow as hell. Added H2O2, still super slow.



[Edited on 4/7/2007 by guy]

Added some KNO3, it really started the reaction going.



[Edited on 4/8/2007 by guy]

tupence_hapeny - 8-4-2007 at 07:50

Yeah, it is slow (mine is at room temp and unstirred),

However, after 24 hours or so, the alloy still has surface markings which were raised still visible. There is a white salt starting to silt the whole thing up (which I presume is probably copper (I) chloride - presumption requires that cold HCl cannot take it to the second oxidation stage) while the liquid is a light yellow-green colour (which is in accordance with what I can find on the net re. Nickel Chloride).

So, from that perspective I suggest that using cold HCl is probably the go if you have the time (speaking weeks not hours) as the two metal salts will be rather easier to separate - given one is soluble and one is not.

NB Nickel (II) Chloride is a soluble, yellow-green salt, while Cuprous (I) Chloride is an insoluble, white salt.

talk about softly, softly catchy monkey

tup

Klute - 8-4-2007 at 07:59

I'm not sure about Ni, but Cu will dissolve in HNO3 in 30min/1h at ~40°C... If the Ni doesn't dissolved that quick, it could be a way of seperating them. Someone give it a try, there's no Ni in the coins of my country (that I know of)...

Nicodem - 8-4-2007 at 08:08

After dissolving the coins in HNO3(aq) and stripping of the solvent…
Hydrated copper(II) nitrate is very soluble in acetone. I'm not sure, but I don't think the same is true for hydrated nickel(II) nitrate. Is that enough as preliminary method of separation? Next you can recrystallize the product.

Edit:
A note to tupence_hapeny: You seem to be unaware that CuCl is soluble in the presence of enough chloride anions as it forms soluble complex salts ( the [CuCl2]- anions ).

[Edited on by Nicodem]

skullandfeather - 8-4-2007 at 13:16

try dissolveing it in nitric w/ a little hcl,
there is a way to separate them with cream of tartar and invert sugar (to precipitate the Cu as a suboxide)

found it in an online library in a inorganic analysis book, cannot find the e-book again, didnt gutenberg used to have more files? i have a hard copy at home, can post it if you guys dont find a better way first:)

sorry this isnt very helpful, i was just looking at this this morning, yaaarrrgghhh!

guy - 8-4-2007 at 13:39

Quote:
Originally posted by skullandfeather
try dissolveing it in nitric w/ a little hcl,
there is a way to separate them with cream of tartar and invert sugar (to precipitate the Cu as a suboxide)

found it in an online library in a inorganic analysis book, cannot find the e-book again, didnt gutenberg used to have more files? i have a hard copy at home, can post it if you guys dont find a better way first:)

sorry this isnt very helpful, i was just looking at this this morning, yaaarrrgghhh!


I know what you're talking about. Add H2O2 and tartrate, with copper salt.

skullandfeather - 15-4-2007 at 14:38

its from "select methods in chemical analysis, cheifly inorganic" by sir william crookes

here it is
http://www.archive.org/details/selectmethodsinc00croorich

Relevant excerpt from the book

Rosco Bodine - 15-4-2007 at 17:14

Quote:
328 SELECT METHODS IN CHEMICAL ANALYSIS.

Dissolve about 2 grammes of the alloy in hydrochloric acid con-
taining a little nitric acid ; evaporate off the excess of acid and dissolve
the mixed chlorides in about 50 grammes of water. To the solution
add about 4 grammes of cream of tartar. Heat slightly to facilitate
solution, and add gradually a solution of caustic potash in alcohol.
The first addition of alkali precipitates the copper and nickel oxides in
the state of hydrates, but an excess of potash redissolves the whole,
the copper and nickel tartrates being soluble in caustic potash. A blue
solution is thus obtained, which after cooling is treated by a solution
of pure glucose or inverted sugar, and boiled for 1 or 2 minutes. The
copper is precipitated as a beautiful red suboxide sinking quickly to
the bottom of the vessel ; if, however, the glucose is added to a warm
solution, the copper is precipitated in flakes which it is difficult to wash.
The completion of the precipitation is ascertained by adding a further
quantity of the glucose solution.

The precipitated copper suboxide is washed, dried, and ignited. It
may be heated with nitric acid, and copper protoxide obtained by
igniting the nitrate so obtained.

The filtrate containing the nickel is evaporated to dryness, the
residue calcined, and then washed to remove the potassium carbonate.
As the incineration can never be complete, on account of the presence
of this salt, the operation is to be repeated. The residue, consisting
chiefly of nickel oxide, is dissolved in aqua regia, and the hydrated
nickel oxide precipitated from the solution by caustic potash. It is
very difficult, if not impossible, to wash this very voluminous oxide,
so the best plan is to wash incompletely, dry, and slightly calcine
the oxide ; after grinding this in an agate mortar, it is easily freed
from the last trace of potash by washing in warm water. The oxide
thus obtained is reduced in a platinum crucible in an atmosphere of
hydrogen.

This process is in use in the Belgian mint, where copper and nickel
alloys are used for coinage.



There are some possible variations on the above method which could be simpler and more economical . And I believe
the process could also work using sulfuric acid with nitric aicd
for dissolution of the alloy to be separated , or perhaps even nitric acid alone could be used .

IIRC , I have used a variation on this process of selective reduction using dextrose , to separate , and sequentially precipitate metallic copper from a copper silver alloy solution of the nitrates , noting the endpoint for copper precipitation
by the color change , and then precipitating the remaining silver as the oxide by addition of a base , instead of continuing the reduction and producing a difficult to remove mirror of free silver metal .

Anyway the point is , that once the reduced copper has been selectively precipitated from the mixed solution of whatever
soluble acid salts of the alloy , then you can manipulate
the residual solution containing the soluble nickel compound
in various ways ......depending upon what form of nickel is
desired . For example , a common form of nickel used for
plating operations and other chemical uses is the double salt
of ammonium sulfate and nickel sulfate , which readily crystallizes in pure form as large crystals of the hexahydrate .

A variation on the old nickel platers process could be used
for managing the residual solution containing the nickel salt ,
after the copper had been selectively reduced and filtered out .

http://www.nbplating.com/nickel_plating_bath.htm

Metallic nickel is readily gotten from the double nickel salt
by either electrolytic or chemical electroless reduction .

Vitamin C would probably also work as a reducing agent .

guy - 15-4-2007 at 17:40

There is an easier way to separate nickel and copper. Nickel sulfate heptahydrate is soluble in alcohol, copper sulfate pentahydrate is not.

not_important - 15-4-2007 at 18:04

Quote:
Originally posted by guy
There is an easier way to separate nickel and copper. Nickel sulfate heptahydrate is soluble in alcohol, copper sulfate pentahydrate is not.


Not quite correct, copper sulfate 5H2O is soluble in ethanol to the extent of about 10 grams per liter, more in methanol; recrystallising the nickel sulfate from water is needed and even then I think a little copper sticks with it.

guy - 15-4-2007 at 18:17

Yeah your right, I read like 1g of copper dissolves in like 300 mL ethanol, probably small compared to nickel sulfate. This would be pure enough for me.

guy - 17-4-2007 at 21:44

I evaporated about 2/3 of my solution and a lot of copper sulfate precipiated. The solution is deep green. I let the solution cool down and more preciptiate came out. Don't know if its both Ni2+ and Cu2+. Anyway, I added about 300mL of denatured alcohol and more precipitate came out but the Nickel still is in solution.

By tommorow or end of the week, I will evaporate the alcohol and find the yield.

guy - 21-4-2007 at 16:06

Ok, the alcohol method is really really bad. 500mL of EtOH got less than 1g of NiSO4*7H2O

So I just added about 69g of Iron Out(bisulfite and dithionite) and Na2CO3 my Cu/Ni solution. I roughly figured the equivalent mass of Iron Out was 91.64g/mol e-. Anyone that has a buret should retest this but the number is close.

This resulted in an orange ppt, most likely Cu2O or Cu. Filterate of this gave a dark green solution. Hopefully this will have a much better yield.

[Edited on 4/21/2007 by guy]

guy - 22-4-2007 at 17:23

I added NaOCl to the NiCO3 solution and I am filtering out the NiO2. However, the solution is purple like permanganate but I am sure that there was no manganese anywhere. Could this be NiO4(2-), a hexavalent nickel compound? I can only find information on it on Webelements.

symboom - 4-10-2016 at 03:16

I got the same thing ive never seen the reaction not sure what compound is formed although makes a good test if your unsure of the carbonate
Copper carbonate reacts into a pale green color

cyanureeves - 4-10-2016 at 18:19

why wont nickel drop with sulfur dioxide from a chloride solution?if nickel remains in solution then why not drop the nickel in chloride solution with aluminum?

[Edited on 10-5-2016 by cyanureeves]