Instructables

How to "Salt Out"

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Step 10: Addendum

Picture of Addendum
You may find that your salted out Isopropyl leaves a salt residue when it is burned. In many applications like a pocket stove the salt residue will continue to serve in the role of helping to separate the Isopropyl and the water when water intrusion occurs from dampness, rain or boil overs.

In other applications the salt residue may not be desired. To separate the salt residue from the Isopropyl use a homemade still. In this case your are not distilling an azeotropic solution of Isopropyl and water but rather separating a liquid from a dissolved solid.

The diagram below illustrates the required components for such a still.

 
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Qcks4 years ago
Just gonna add...
If you're having issues with salt residue in your isopropyl, you can limit the solubility of the Sodium Chloride by doping the isopropyl with sodium hydroxide prior to salting it.

This has the advantage of having a solvation effect with the salt and the base (Sodium Hydroxide competes with Sodium Chloride for solvation with the water because both have a sodium cation). Any residual hydroxide compound should burn clean.

The biggest downside is that you might begin to push your isopropyl to undergo a synthesis reaction, but due to it's shape that's not very likely (that is to say, it's stearically hindered, and thus, unlikely to undergo any synthesis reactions).
lpkid1057 Qcks4 years ago
Love the pedantic organic chemistry guy here.