Sciencemadness Discussion Board - Copper (ii) Oxide Powder from Wire Scraps

Copper (ii) Oxide Powder from Wire Scraps

Tungsten.Chromium - 5-4-2018 at 08:23

Recently I have looking to learn a bit more about inorganic chemistry and was recommended to look into making some copper salt crystals as a starting point.

Most of the reactions I can find involve dissolving a copper base into an acid to get the resulting salt. The starting point for many of these replacement reactions seems to be copper (ii) oxide. In an effort to save some money and explore the world around me vs buying everything online, I'd like to prepare my own copper oxide powder.

Between working for an electric motor company and having a few electrician friends, I am in no shortage of copper wire scraps. What I would like to do is strip the wire and oxidize it to get the desired copper base. I am planning on using the process outlined below.

1) Strip the shielding off the wire to give copper strands
2) Cut the wire strands into short pieces 1" or less each
3) Grind the strands into a powder using a small ball mill (I'm not sure if I'm going to buy one of these or try and throw a DIY setup together)
4) Heat the powder in a metal pan to oxidize the copper
5) Wash the Copper Oxide powder with water to remove water soluble impurities

What is the general consensus on this process. I understand it will be labor intensive and time consuming, but I'm not worried about efficiency right now as much as seeing the process in action. Thanks!

DraconicAcid - 5-4-2018 at 08:48

I'm not sure how thoroughly the copper powder will oxidize in air. If I were you, I'd react the copper with an acid and hydrogen peroxide, precipitate the copper as the hydroxide, and heat the suspension to give the oxide. Collect by filtration, and wash with acetone so that it dries in a reasonable amount of time.

crystal grower - 5-4-2018 at 09:16

You can also dissolve copper in acid using electrolysis, then, as Draconicacid said, precipitate as hydroxide or carbonate. I'd suggest keeping the hydroxide instead of heating it, as the copper hydroxide will very gladly react with almost any acid to give the product you aim for.

Fulmen - 5-4-2018 at 09:16

I won't comment on the direct oxidation, but if you're going for a wet process avoid the direct precipitation route. It produces a very fine suspension that is almost impossible to filter. The best route I have found uses a mixture of ammonium carbonate and ammonia, this dissolves copper in combination with atmospheric oxygen. Boiling off the ammonia produces a dense precipitate of basic copper carbonate which is easy to filter, this can in turn be heated to produce copper oxide.

DraconicAcid - 5-4-2018 at 09:22

I've found that copper(II) oxide filters out much more easily than copper(II) hydroxide.

crystal grower - 5-4-2018 at 09:26

Can't argue with that.

LearnedAmateur - 5-4-2018 at 10:36

When preparing copper salts, I’ve always done the following:
1. Add copper metal (tubing in my case) to a vessel and add slightly less concentrated sulphuric acid than you’ll need. Alternatively, use as much sulphuric acid as you’ll need for a specific amount of copper salt.
2. Dissolve equimolar (WRT H2SO4) potassium nitrate in an appropriate volume of water.
3. Drip in the nitrate solution to generate nitric acid in situ, which is one of the only acids capable of directly reacting with the metal.
4. Add sodium carbonate solution until solution is no longer blue/no more precipitate forms

The resulting carbonate is easy to filter using either a fritted Büchner (recommended) or paper filter. If using the former, your carbonate (after a wash to remove residual solubles) can be converted in the filter by adding any acid until it stops bubbling, which minimises mechanical losses of yield.

This is a waste of reagents on the large scale, where electrolysis in diluted H2SO4 wins out, but if you want to produce several grams of copper salts for crystal growing then I’ve found it works perfectly and quite quickly too. If you want to get to the oxide, then just heat the carbonate until it’s all black. Any excess copper metal remaining, as I usually find with pipe, can subsequently be reused in the next batch.

Tungsten.Chromium - 6-4-2018 at 20:26

Quote: Originally posted by DraconicAcid

I'm not sure how thoroughly the copper powder will oxidize in air. If I were you, I'd react the copper with an acid and hydrogen peroxide, precipitate the copper as the hydroxide, and heat the suspension to give the oxide. Collect by filtration, and wash with acetone so that it dries in a reasonable amount of time.

I think this is the route I am going to try, using acetic acid (vinegar) as the acid. Can you please explain what the need for the hydrogen peroxide is tough? I've read that you can add copper metal to nitric acid to give copper nitrate without needing hydrogen peroxide. Does the hydrogen peroxide need to oxidize the copper before it can be replaced with the acetate ion?

Might need to move this to beginnings...

DraconicAcid - 6-4-2018 at 20:31

Quote: Originally posted by Tungsten.Chromium

Most acids are not strongly oxidizing enough to oxidize copper. Nitric acid will work, but most other acids will require the addition of hydrogen peroxide. Hydrochloric acid will work as long as you allow it long exposure to air.

RogueRose - 6-4-2018 at 20:55

Quote: Originally posted by Tungsten.Chromium

Quote: Originally posted by DraconicAcid

You might be able to get away with boiling the wire in vinegar and the airation of the bubbles might be enough to help oxidize the wire. I've done this and the results were pretty good. IDK if it would help to dilute the acid even more than 5% as the longer it boils the more air will dissolve into the water. You are basically trading energy for boiling for the H2O2, but IDK how efficient this is.

If you don't have access to concentrated H2O2 then buy medical 3% and add equal portions of vinegar and H2O2 and boil it together. I found that using a 2.5%/2.5% acetic acid/H2O2 gives a lot of foam/bubbles and can cause a real mess. It may be best to add the peroxide slowly. I had a head of foam about 8" high in a tall pot. It also made a good bit of CuO when it was heated until the acid dissolved it.

Fulmen - 6-4-2018 at 23:33

I doubt boiling will aid in oxygen absorption. First of all warm solutions dissolve less oxygen, and the vapors produced will prevent air from getting in contact with the liquid. Using oxidizers like nitrates or peroxide will speed things up, but if you're not in a rush then air should work with any acid. Having some sort of circulation or a pump for aeration would be beneficial.

TheMrbunGee - 7-4-2018 at 00:10

1:
https://www.youtube.com/watch?v=pXXKxUYuNZQ&t

2:
https://www.youtube.com/watch?v=ji75TO2D0Rc

[Edited on 7-4-2018 by TheMrbunGee]

[Edited on 7-4-2018 by TheMrbunGee]

wg48 - 7-4-2018 at 02:07

Quote: Originally posted by TheMrbunGee

1:
https://www.youtube.com/edit?o=U&video_id=pXXKxUYuNZQ

2:
https://www.youtube.com/edit?o=U&video_id=ji75TO2D0Rc

Wow those links had me confused. I had not looked at my UT channel for a while. I have only have about a miserable 100 views.

TheMrbunGee - 7-4-2018 at 04:52

Quote: Originally posted by wg48

Quote: Originally posted by TheMrbunGee

1:
https://www.youtube.com/edit?o=U&video_id=pXXKxUYuNZQ

2:
https://www.youtube.com/edit?o=U&video_id=ji75TO2D0Rc

Wow those links had me confused. I had not looked at my UT channel for a while. I have only have about a miserable 100 views.

1:
https://www.youtube.com/watch?v=pXXKxUYuNZQ&t

2:
https://www.youtube.com/watch?v=ji75TO2D0Rc

I can't even do links.

fixed them.!

CaCl2 - 9-4-2018 at 23:00

If you have the time time to wait, but don't have hydrogen peroxide, acetic acid vapour mixed with air are actually pretty effective at corroding copper.

The copper acetate can then periodically be washed of.

This was used to produce verdigris in the middle ages, I think.

Once you get the copper dissolved, it can easily be converted into the oxide by the methods people have listed above.

[Edited on 10-4-2018 by CaCl2]

AJKOER - 11-4-2018 at 15:47

The action of an oxygen source (O2, H2O2 where dilute is fine,..) on aqueous NH3 (where the ammonia is first added to the copper metal, thereby saving H2O2 from a decomposition reaction with copper surface oxides), proceeds mainly by an electro-chemical reaction and some side reactions.

As such, add a small amount of sea salt to function as an electrolyte. I recommend jump starting the reaction for 30 seconds in a microwave.

Some of the underlying chemistry, which is, in part, electro-chemical in nature (which is why I recommend adding a good electrolyte to promote the reaction):

2 Cu + 4 NH3 + 1/2 O2 (or H2O2) + H2O --> 2 [Cu(NH3)2]OH (see half cells and Cu(l)/Cu(ll) and Cu/Cu(ll) equilibrium reactions at https://onlinelibrary.wiley.com/doi/abs/10.1002/bbpc.1963067... )

2 [Cu(NH3)2]OH + 4 NH3 (aq) + 1/2 O2 + H2O --> 2 [Cu(NH3)4](OH)2

Cu + [Cu(NH3)4](OH)2 <---> 2 [Cu(NH3)2]OH

Additional source: see "Kinetics and Mechanism of Copper Dissolution In Aqueous Ammonia" fully available after signing on to ones Facebook account at http://www.academia.edu/292096/Kinetics_and_Mechanism_of_Cop...

If, as a consequence of a standard chemical side reaction, some NH4NO2/HNO2 is also be formed (per the cited reference) usually within the first 1O minutes of the reaction (per my observation), you can personally observed the decomposition of any formed HNO2/NH4NO2 (well, at least if one uses cheap household ammonia that foams owing to the presence of surfactants, which can actually create a column of foam as the decomposition takes place). Caution, in a sealed vessel, eruption/spillage can occur.
----------------------------------------------------------------------

More details on a leaching solution with added ammonium carbonate, see https://www.researchgate.net/publication/229233363_Dissoluti... .

[Edited on 12-4-2018 by AJKOER]

VSEPR_VOID - 11-4-2018 at 20:09

I highly recommend electrolysis. Well you could use hydrogen peroxide and an acid this would be expensive in the long run. It is better to use your funding on things other than gallons of vinegar and liters of OTC peroxide. You can use nearly any power supply for this, maybe even a phone charger. If you plan to do more electrochemistry than invest in a variable bench top supply. Just pass a current through copper wires (you can use both a copper anode and cathode) submerged in a very weak solution of Epson salt (MgSO4).

Copper chemistry is the most interesting and assailable for the learning amateur. There seems to never be an end to all you can do with this beloved transition metal. Try your hand at making complexes with ammonia, or if you are feeling adventurous prepare ferrocyanide double salts.

ninhydric1 - 11-4-2018 at 21:44

I've done the electrolysis route before. Just make sure that the cathode isn't too submerged into the electrolyte otherwise too much copper will plate out and possibly short your electrolytic cell.