Reducing Cu and Ni with Zn

I read a blurb online about how zinc will not reduce nickel ions even though Zn is above Ni in the potential series.

https://www.nature.com/articles/142210a0

I thought this might be a useful way to separate copper from nickel, but I can't find any mention of it searching through the threads on that topic.

I decided to do a test and share what I did for feedback.

Here are two test tubes. The one on the left contains 1 mmol of CuSO4 and the one on the right contains 1 mmol of Ni2NO3.



Here are the same two test tubes one day after a slight excess of Zn dust was added.



The Cu test tube looks like all the Cu has reacted. To make any Cu ions more visible, I added 5 drops of 30% NH4OH. Here is a pic right after adding the ammonia before shaking,



and after shaking.



Am I right to conclude that the lack of visible blue means all the Cu has been reduced?

To see if any of the Ni was reduced, I used a neodymium magnet to try and move around the solid material in the Ni test tube. Here are pics I took while moving the magnet around the solid material. They're not the best pics because I twisted the tube between pics, but it was clear to me the solid material didn't move at all.





I think the next thing I'm going to do is try to plate the nickel out of solution. I'll update the post if I do.

Quote: Originally posted by Fluorite

You can also use aluminum to reduce nickel metal The reaction is not vigorous as with copper compounds but it happens To see if there's any copper ions left in the solution you can bubble hydrogen sulfide or use sodium or ammonium sulfide to precipitate dark copper sulfide, zinc sulfide is white so it should not be a problem

Quote: Originally posted by Bedlasky

Nickel react better with zinc or aluminium in the presence of chloride ions. Reaction is very fast and very exothermic (when I made nickel metal using aluminium and NaCl, reaction was so exothermic that I must cool the mixture). Nickel made by this way isn't pure even after several hours in concentrated NaOH (mine is 93,5% or so).

Quote: Originally posted by electrokinetic

It is interesting that the Urushibara article specifically named NiCl2 as the nickel salt in the preparation of nickel using zinc.

Quote: Originally posted by Bedlasky

NaOH remove leftover aluminium. Al react with NaOH to form [Al(OH)4]- and H2 gas. Nickel doesn't react with NaOH. Chlorides help to proceed the reaction because of dissolving Al2O3 protective layer on the surface of aluminium (formation of [AlCl4]-). For zinc it is similar.

Here is the test tube a day after adding ten drops of saturated sodium chloride solution. There appears to be no change:



Right after adding a strip of aluminum foil:



And then 3 days later, where there does seem to be some cloudy material near the bottom. Test with a magnet for nickel was negative: