tsathoggua1 - 4-7-2017 at 08:47
Here is a question for all of you.
If you say, forgot about a crucible made of graphite, a large one, and had it in two big slices, after it had absorbed KOH, NaOH as a mixture, and
sat for a long, long time, weathering perhaps and being rendered porous, and more so on being hit with a hosepipe, I think perhaps it may have
intercalated (and had removed now) some NaK, which of course would affect the internal structure of the graphite (would NaK be intercalated as an
alloy or would graphite selectively absorb just the potassium, since it does not so well absorb Na as it does K?)
Tried keeping the crucible in one piece, but now I do have the bottom as a disk and fair sized slices of the resulting modified graphite structure.
Can't help but think, it might perhaps be useful as a salt bridge, potentially, of quite inert nature. What do you think to that idea? It'll need
drying for any molten salt-based procedures, but should be impregnated with NaOH/KOH and carbonate salts derived from these.
Any ideas for interesting electrochemical uses? (or anything else, catalyst supports if some of the material were ground up, etc? Its got quite an
opened-seeming, flakey texture and made far more brittle than it was, after being forgotten for quite some time. I'd like to see some sort of new life
for it, albeit not as a crucible anymore. NaOH/KOH mixture seems a lot more aggressive towards graphite than does either hydroxide alone. There must
be some use for this material. Even if it only ends up being leached of salts, and being used for producing potassium graphite as a reducing agent.)
Sulaiman - 4-7-2017 at 13:02
Due to its electrical conductivity I doubt that it would be useful as a membrane/divider for an electrolytic cell,
the graphite would act as an intermediate electrode.
I think that 'glassy' graphite crucibles are mostly carbon
but the coarser types use a binder, clay of some type I believe,
so you probanly dissolved away the binder only as graphite is quite inert.
tsathoggua1 - 16-7-2017 at 13:16
It wasn't a glassy carbon type. It was graphite. I've two different types (or had), most being matte black, but this one did indeed appear to be
graphite, silvery and quite soft, quite irregular in shape and rough-textured on the surface (prior to any chemical attack). The vitreous carbon
crucibles/boats I've ever seen depicted did indeed look glass-like, the kind of thing that would break with a conchoidal fracture and leave a sharp
edge, whilst this if gone at with a sharp implement would (again before exposure to anything) flake off at the point of contact in a lamellar-type
manner.
The matte-type ones I have will stand up to being used for electrolysis of a molten caustic potash/NaOH mixture without visible attack, whereas this
one appeared to be quite susceptible to attack.
[Edited on 16-7-2017 by tsathoggua1]