I'm using potassium thiocyanate solution in water for optical purposes (matches glass refractive index), but the KCNS I bought is only 98% purity and
has a beige tinge. Other than filtration, is there any simple process to improve the transparency? I can't buy more pure stuff as I'm using five
kilograms of it and the more pure is much more expensive.12AX7 - 26-12-2005 at 14:18
Recrystallize?kclo4 - 26-12-2005 at 15:41
Perhaps another solvent that will not disolve the impurity but will the KCNS or visa versa? Do you know what the Impurity is?chromium - 26-12-2005 at 16:03
I have data that KCNS is soluble in acetone, ethanol and amyl alcohol. Most substances are not so this may be of some help.
Solubility in acetone is 20.75g/100g @ 22C
[Edited on 27-12-2005 by chromium]Quince - 26-12-2005 at 16:18
Hmm, that's 5% solubility. I'd need 25 kg acetone... I guess I'll try a finer filter, as maybe the impurities are not dissolved in the water but
just very fine.Darkblade48 - 26-12-2005 at 18:19
Quote:
Originally posted by Quince
Hmm, that's 5% solubility. I'd need 25 kg acetone... I guess I'll try a finer filter, as maybe the impurities are not dissolved in the water but
just very fine.
Er, the solubility is 20%
Quote:
Originally posted by chromium
Solubility in acetone is 20.75g/100g @ 22C
neutrino - 26-12-2005 at 19:25
I remember Vogel recommended using a small amount of activated carbon to remove colored impurities. I'm not sure why this wouldn’t take up other
organics as well, but it's said to work.BromicAcid - 26-12-2005 at 21:45
Other then filtration? So the impurity is insoluble? Is it the solution that has a beige tint or the solid KCNS? If it is soluble the use of norwit
(I think that's what it is called) is what is done in orgo labs, it is just a form of activated carbon I think, you add it to your soluiton and heat
it some with stirring, if your impurity is organic it may adhere to the surface of the carbon and decolorize your solution as Neutrino suggested.Quince - 26-12-2005 at 23:07
The solution has some tint; the solid KCNS is white.chloric1 - 27-12-2005 at 07:53
Quote:
Originally posted by neutrino
I remember Vogel recommended using a small amount of activated carbon to remove colored impurities. I'm not sure why this wouldn’t take up other
organics as well, but it's said to work.
I can verify this claim with personal experience. I purchased activated charcoal for fishtanks for this purpose. I had an ammonium sulfate solution.
otherwise of good purity, that was colored yellow. Previous attempts to precipitate the color had failed. Additionally, the color was not cloudy but
prefectly clear so it was a really good sol. After a few days being mixed with a substantial quantity of charcoal and filteration through some
diatamacous earth, a solution with the white clarity of Deionized water was formed!
