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Author: Subject: acid/base extraction of iodine

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Registered: 14-11-2012
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[*] posted on 17-11-2012 at 11:11
acid/base extraction of iodine

I knew that iodine was soluble in nonpolars (I think aromatics are the most capable solvents), but I wasn't sure whether it can be recovered by putting such a solution over an alkaline solution. Turns out it does so very well.

One might be wondering why one would want to do such a thing - well, the iodine was hiding in a mix of various ions, and suspended low solubility materials, and when the solution finally turned red from acidic pH and addition of H2O2, it seemed to refuse to form usefully large crystals. You could tell it was in there by the smell and colour but it wouldn't budge. So extracting into naptha was tried.

Naptha was basically put on the acidic iodine-hiding solution, given a good mixing, separated and added to another flask with a fairly strong solution of sodium hydroxide. Given enough agitation all the purple/pink in the nonpolar would wash out, then this was repeated until the nonpolar became virtually colourless.

There was some kind of bleh that ended up coming across, the lye solution with iodides in it became quite milky and there was lots of suspended fine salt crystals (either sodium phosphate or sodium chloride most likely). That filtered out easily. The end result was the iodine was isolated quite effectively and should then behave itself when oxidised again without all the suspended bleh floating about.
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