If working with a crude distillation apparatus (no temperature control, just heats til boiling and stops once distillate hits a given volume) getting
a perfect 95% azeotrope is not really doable. However, with multiple crude distillations yields ~80% ethanol pretty quickly.
My question is what could be added to the 80% ethanol pre-distillation to help it get to 95% even when distilling at overheated conditions? Perhaps
adding a bunch of adhydrous MgSO4? Or CaCl2? Or MgCl2?
I'm not sure what would hold the water best through the heat, if any of those.Fery - 25-10-2022 at 13:05
That led me down a rabbit hole of the Hofmeister series. Apparently the tribasic citrate ion might be better than carbonate. From experience I know
that trimagnesium citrate really likes water, and has no problem solidifying as an amorphous, resinous hydrate. Might be something workable there by
letting magnesium oxide react with citric acid in the water/ethanol mix.
Also learned that lixivium is a word (meaning a solution of wood ash), that would make for a contentious scrabble win.Fery - 25-10-2022 at 20:44
MgO + citric acid would produce extra water. Kitchen / food grade citric acid is monohydrate which introduces extra unwanted water.
You can buy cheap and not extra pure K2CO3 . 1,5 H2O in shops for home soap producers, but they sell sesquihydrate - you can dehydrate it by heating.
Using anhydrous K2CO3 would improve your yield by not adding extra water into the mixture.
I used K2CO3 to dehydrate allyl alcohol and I was able to recover a little of alcohol from water phase, but only a little, most of it was in organic
phase. For isopropanol I used kitchen NaCl which is much weaker dehydration agent and I recovered alcohol from water phase too, but NaCl does not work
with ethanol. I did not dehydrate ethanol yet, I produced azeotrope by Hempel column + Rashig rings + variable reflux ratio head.
I used K2CO3 and KOH for salting out dioxane but that is ether. NaOH for pyrrolidine but that is a secondary cyclic amine. I remember using NaOH to
remove denaturing shits from commercial ethanol (methylethylketone by aldol condensation).
Using K2CO3 for allyl alcohol was quite tedious and long lasting method, later I used azeotropic distillation which was faster and better. Also
instead NaCl for IPA I would use column distillation but I did not yet have the glass equipment when salting out using NaCl.
[Edited on 26-10-2022 by Fery]Mateo_swe - 26-10-2022 at 02:26
What about Cu salts?
I dont remember exactly what Cu salt, but its one of the more common ones.
Its used to make anhydrous ethanol so it might be worth looking into.
I know there is youtube videos about it.
