Schildkröte - 31-8-2018 at 11:15
Hello, I tried electrolysis of impure zinc sulfate with little piece of platinum wire&sheet. The solution was originally transparent yet after few
hours of electrolysis the solution around the anode got pink, then purple. The platinum anode developed a thin film of red substance on surface which
started to fall of. Because I got scared that I will lose my platinum I took it out and put it in solution of sodium dithionite which immediately
returned the shiny surface of platinum back.
I'm not quite certain what happened, I guess the purple color was from manganese impurities which oxidized the surface? May the red substance be
chloroplatinic acid?
Anyone got an idea how to prevent the damage to electrode?
zed - 4-9-2018 at 15:41
Hmmm. Chloroplatinic acid can be formed by anodizing Platinum in concentrated HCl.
Platinum doesn't usually react with -SO4, but when anodized..... Maybe? Dunno!
I have done the trick, of anodizing items that are Chrome plated..... in Copper Sulfate solution, turning the Chromium Dull/Black..... Then reversing
the current, to plate out copper on the activated surface. Making it solder-able.
Sorry I can't be more helpful.
Schildkröte - 9-9-2018 at 13:07
Thank you for effort anyway! I will try to find another way out.
Eianz - 9-9-2018 at 22:51
Its due to electrolytic passivation