Eric Slighton
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Eliminating Sugars
I have a solution of NaI contaminated with various sugars... Is there a way to decompose the sugars or otherwise separate the two?
I've tried drying it and then mixing in acetone since NaI is soluble while sugar is less so, but that does not seem especially effective.
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Zombie
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What about standard re-crystallization?
I'm not up on this but to purify a crystal you repeat the crystallization process several times.
yield goes down as you remove the impurities, and that's a good sign that it is working.
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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smaerd
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Without some kind of ion exchange resin I can't think of anything. Except... Maybe generate iodine insitu and sublime the iodine onto something. Then
reduce the iodine back to sodium iodide. The problem is most conditions for this will oxidize the sugars to a black steamy char. I'm not sure if the
iodine would even be recoverable. It may get lost in the mess, but maybe the mess could be ground up and heated->sublimed.
Maybe someone else has a better way, I just wish I understood the situation/why you want to do this. There seems like there's a better way to do
whatever you're trying to do.
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j_sum1
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I have a student who recently undertook a project to separate NaCl from sucrose. (Approximately 50% mixture.) It proved reasonably difficult
First approach was to find a selective solvent. Nothing that we had available worked. NaCl is not really soluble in acetone. If you can find a
suitable solvent then this is definitely the method I recommend.
Second approach was to recrystallise -- exploiting the fact that NaCl has a rather flat solubility curve while the solubility of sucrose is highly
temperature dependent. I think the method she finally settled on was to mix up a solution at high temperature and slowly boil off the water. There
reached a point where the salt dropped out as a precipitate while the sugar remained dissolved. That was followed by decantation and washing of the
salt crystals. Fairly substantial losses and I am not sure how pure her product was. It is likely that more than one recrystallisation will be
needed.
A third option would be to calcine off the organic material. Likely to be messy and you will get carbonaceous material mixed in with your NaI. If
you are able to roast with enough oxygen you should eventually drive off organic impurities as CO2.
A bit depends on the amount of impurity, the purity you require, what volume of material you are working with and what level of loss you are willing
to sustain.
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BromicAcid
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Quote: Originally posted by j_sum1  | | A third option would be to calcine off the organic material. Likely to be messy and you will get carbonaceous material mixed in with your NaI. If
you are able to roast with enough oxygen you should eventually drive off organic impurities as CO2. |
I wouldn't think you would need to calcinate, sugars break down at reasonable temperatures, albeit messily. Heat until the water evaporates and the
sugars break down then smash up the resulting mess (which may prove difficult, those carbon deposits can be a pain when they are
<i>untinentially</i> created), extract with water, filter, and evaporate again. At least that is what I would try first on the test tube
scale.
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