wackyvorlon
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Salting out Methanol
Recently I bought a jug of -40 car windshield washer fluid with the plan to extract some methanol from it. With distillation, I've managed to get
about 300ml of 90% ethanol. To reach this point required distilling twice, which is pretty time consuming.
I decided to try salting out the methanol, some googling lead me to believe that I could do so with sodium chloride. I made up a saturated solution of
sodium chloride, and added 50ml of that to 50ml of methanol in a 125ml sep funnel. I shook and vented a few times, then let it sit. Almost immediately
the salt came out of solution. I've attached a picture, I'm going to say that it seems that this is not a viable method of removing the remaining 10%
of water. Any suggestions?
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ParadoxChem126
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In this example, methanol has a greater affinity for water than sodium chloride does. As a result, the methanol forces the salt out of solution, not
the other way around.
To increase the concentration from 90%, fractional distillation and/or molecular sieves can be used.
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JJay
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Fractional distillation should remove almost all of the water if you go slow. I'm distilling some methanol as we speak, but I usually get mine from
dry gas (which probably doesn't even require distillation, but I'm doing it just in case there are additives).
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BromicAcid
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You should still be able to edit your post to correct this to methanol. Interesting note is just because this does not work with sodium chloride,
does not mean salting out is off the table. As ParadoxChem said, in this instance the methanol has a greater affinity for the water, or as I look at
it, the water has a greater affinity for the methanol than the sodium chloride. Anyway, there is a thread kicking around here somewhere where
chemists are salting ethanol out of water. Although I would think it would be even more difficult to salt out the methanol, there might be some good
salts to try in that thread.
http://www.sciencemadness.org/talk/viewthread.php?tid=61746
http://www.sciencemadness.org/talk/viewthread.php?tid=24299
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macckone
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Anydrous epsom salt is likely to work better. But it will absorb some methanol as well. Potassium carbonate works with high proof ethanol, that
might work as well.
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CaptainPike
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Fractional Crystallization!
If only 10% water remains, try putting it in your freezer. The water ice might freeze out, filter with cold apparatus.
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unionised
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Quote: Originally posted by CaptainPike  | Fractional Crystallization!
If only 10% water remains, try putting it in your freezer. The water ice might freeze out, filter with cold apparatus. |
Are you aware that one of the uses of methanol is as an anti-freeze?
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macckone
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That might work with butanol or pentanol but not lower alcohols.
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Radagast97
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| Quote: Originally posted by CaptainPike | Fractional Crystallization!
If only 10% water remains, try putting it in your freezer. The water ice might freeze out, filter with cold apparatus. |
Wrong side of the phase diagram. MeOH has a higher freezing point than MeOH with 10% water.
Second, your freezer better go down to ~-100C.
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aga
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I'd forgotten about that, and it is not so long ago.
Needs re-visiting, certainly.
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