Sciencemadness Discussion Board

Aluminate/cobaltate solution

LanthanumK - 6-7-2011 at 04:16

Theoretical situation: I have a solution of aluminium and cobalt hydroxides in sodium hydroxide solution. I want to separate them. I think that adding sodium hypochlorite solution will oxidize the cobalt(II) to cobalt(III), precipitating cobalt(III) oxide and leaving the aluminate behind. Is there anything wrong with this method?

barley81 - 6-7-2011 at 04:50

This sounds like a good idea to me, but then again I haven't tried it. I don't see any problems.

Here's my idea to do this:

You may try acidifying to neutral pH, then adding ammonia and shaking to dissolve oxygen. IIRC aluminum doesn't form a complex with ammonia, and cobalt does. The cobalt ammine complex will oxidize to become cobalt (III), and aluminum hydroxide will precipitate (very little aluminate formed).


[Edited on 6-7-2011 by barley81]

LanthanumK - 6-7-2011 at 06:37

If the fact about cobalt forming an ammine complex is true, then other parts of my process is wrong. Thanks for enlightening me.