nezza - 27-5-2017 at 23:37
I have some nice vanadium crystals as part of my element collection. I did not take any particular care over their storage and now they have a green
coating of ?oxides. What is likely to be the best way to clean them and get them back to their former glory ?. I will seal them under argon once
clean.
j_sum1 - 28-5-2017 at 00:29
I have never dealt with this particular problem -- My V sample is vacuum deposited crystals stored under argon.
Coincidentally, thiosoi2 (on yt) did a video this week on vanadium. He demonstrates cleaning crystals using nitric acid. Not sure of the
concentration.
nezza - 28-5-2017 at 01:20
Thanks for that. I'll give it a go with Nitric acid. I note in the video he says nitric acid will dissolve vanadium to give vanadyl chloride. I think
he means aqua regia.
Neme - 28-5-2017 at 04:47
In the comments he said that he used nitric acid and just did a mistake saying chloride.
Texium - 28-5-2017 at 05:58
Nitric acid does work very well for cleaning vanadium, as it does appear to be quite resistant to it. Even heating vanadium in nitric acid will only
cause it to partially dissolve, to yield a faint blue solution, presumably vanadyl nitrate. However, I was successful simply using ascorbic acid to
remove the oxide coating on the vanadium turnings that I have, with no noticeable damage to the metal at all.
On a related note, does anyone know why it is that vanadium metal is so hard to oxidize, while it is also hard to reduce solutions of it to the metal?
Based on the behavior of its solutions I'd have expected the metal to have a reactivity similar to that of manganese.
violet sin - 28-5-2017 at 18:11
The ascorbic acid worked great for me as well, shiny clean in no time, leaving a nice blue solution
nezza - 29-5-2017 at 05:44
Thanks Guys. I liked the idea of using an organic acid as most are slight reducing agents and will not oxidise the Vanadium any further. Anyway I used
Tartaric acid and these are the cleaned and washed crystals. I will now store them under Argon to keep them clean.
