Ok so im in need of some anhydrous alcohol or near enough to it.
I'm guessing that 95% denatured ethanol is not anhydrous,that 50ml
of whatever it is (denatonium benzoate,mek,mibk,wood naphtha etc)
is probably at least half water coz they aren't really detectable by smell
and are only there to deter ppl from drinking it.anyways I've enquired about methanol
and unless I want a 20litre drum its gunna cost a lot.isopropanol is also out of my price range so what I want to know is without molecular sieves
what is the best way to go about drying it out a bit more? Dump in 100grams of mgso4 or calcium chloride
or silica gel or something else.potassium carbonate will take to long to get here
so if anyone has any advice or experience with doing this please comment.Nonexistent - 26-2-2020 at 23:21
I've read somewhere in a very old compendium that agar and or gelatin absorb water but not ethanol and it should be enough to at least increase the
ethanol %, haven't been able to verify though.
Sodium metal should not be used, it reacts with ethanol.
You can use anhydrous MgSO4 (which can be made easily from hydrated MgSO4.7H2O) to absorb the water and then distill of the ethanol.Nonexistent - 27-2-2020 at 00:13
welp, I really need to recap my o-chem before posting again. Doing only analytical for a year seems to have rotted my brain a little. Fery - 27-2-2020 at 01:34
rfx with CaO
3A molecular sieve
azeotropic distillation dehydratation (benzene works surely, perhaps hexane could be used too)draculic acid69 - 27-2-2020 at 03:41
Should have mentioned trying to do this as cheaply as possible so buying stuff isn't an option.i suppose mgso4 is the easiest way.ill give that a go.Fery - 27-2-2020 at 03:48
then pls report the concentration of water still present after the dehydratation process or at least try it with KMnO4 crystalTsjerk - 27-2-2020 at 04:40
MgSO4 should get the ethanol past 99%, I got half a kilo of "bitterzout" some time ago for about 2 or 3 euro without shipping.
What is the volume of ethanol you need? If only something like 100 or 200 ml you could dry some of the hydrated MgSO4 in a microwave between two bowls
or plates.
When the product is described as denatured 95% ethanol they mean they got 95% ethanol and that was denatured by adding a percent or two of the
denaturing stuff. So there is definitely more than 2,5% water in there.
Can you get bioethanol for ethanol burners? It is the same stuff but they start with 99% ethanol, which is probably 99,5% or close to that. The 95%
would make the burner produce black residue.
MgSO4 should get the ethanol past 99%, I got half a kilo of "bitterzout" some time ago for about 2 or 3 euro without shipping.
Googled "bitterzout" hoping you had found a cheap source for a bittering agent like denatonium benzoate.
Alas, my hopes were crushed…
I get my MgSO4 from the pharmacy where it is sold in 30 grams bags. Convenient but expensive.
Rock salt
MadHatter - 27-2-2020 at 08:40
People who distill ethanol for fuel purposes often
run it through rock salt because NaCl is insoluble
in ethanol. The rock salt absorbs the H2O to
some degree. Then heat(can be done in sunlight)
the rock salt to drive off the H2O. Repeat the
cycle until you have an anhydrous product. Tsjerk - 27-2-2020 at 08:51
Nein Herr Haber! Das ist ein Salz welches bitter schmeckt
Probably made a grammatical mistake there. Fery - 27-2-2020 at 09:12
Yes but MgSO4 from pharmacies is MgSO4 . 7 H2O, it is used often for clearing colon before colonoscopy (30% water solution, 2 x 100 ml drink and sit
on toilette as its power is brutal - I just heard, did not try myself). However, today we have more choices, and more gentle solutions, MgSO4 is very
old method.
Did you dry the heptahydrate? How high temperature does it require to dehydrate it completely (lose all 7 H2O)?
Years ago I tried CaO method, even after that the ethanol contains some water and if required extremely dry, other reagents necessary to dry it
further.Tsjerk - 27-2-2020 at 09:35
Did you dry the heptahydrate? How high temperature does it require to dehydrate it completely (lose all 7 H2O)?
The photo below shows the left overs from the last time I dried some of the hepta hydrate in my microwave a couple of days ago. I use cups like this,
one containing the hydrate, the other sitting on top. Water vapor can escape from between the two cups. Magnesium sulfate forms a solid clump, sodium
sulfate stays a bit more fluffy.
I'm pretty sure in both cases the product is the fully anhydrous stuff. It turns any cloudy solvent clear in minutes.
I microwave a couple of minutes at 1000 Watt, the nice thing is that the salt and the cups don't heat up anymore as soon as all water is gone. So when
there is no more steam coming of I let it go for another 30 seconds and then leave it to cool until I can take it out of the microwave.
[Edited on 27-2-2020 by Tsjerk]
Heptylene - 27-2-2020 at 14:24
Maybe you could use plaster of paris? Very cheap and shoud get some water out of the ethanol. The plaster might become hard so I would choose the
container taking this into account (a bucket maybe?)Fery - 27-2-2020 at 23:11
Heptylene that's a way to go too.
CaSO4 + 1/2 H2O -> CaSO4 . 1/2 H2O is very strong desiccator, but perhaps the lowest efficient one.
Some desiccators absorb also a lot of ethanol thus decreasing yield. Tsjerk - 28-2-2020 at 00:03
If you want to go for efficiency, go for CaO. As it actually reacts with water you don't have to filter, just distill to dryness. draculic acid69 - 28-2-2020 at 04:11
then pls report the concentration of water still present after the dehydratation process or at least try it with KMnO4 crystal
I actually have no way of figuring that out.draculic acid69 - 28-2-2020 at 04:49
Mgso4 is sitting on the bottom of about 400ml but then I thought the more the merrier and added some cacl which fully dissolved and turned everything
green.i think that 3A molecular sieves are cheap enough to buy and are going to be a sure thing with no need for distillation.i think a small amount
of the mgso4 will stay in the ethanol requiring distillation which I want to avoid bcoz ethanol and water take ages to evaporate.i think I'm gonna
just go with the sieves considering
price, ease(stir,leave,filter that's it), reusability and there multiple uses other than this one.i want to try grignards soon and I can use them
there as well so less than$20 for an unending ability to dry stuff seems worth the investment and will be the best results for the least effortmorganbw - 28-2-2020 at 07:49
I am thinking that Calcium Chloride and Ethanol do not play well together.draculic acid69 - 28-2-2020 at 21:20
No they do not.completely dissolves.useless for ethanol.BromicAcid - 29-2-2020 at 17:06
Lots of threads on this floating around, there was an interesting bit on using corn cob floating around out there showing that it was cheap and
effective. draculic acid69 - 29-2-2020 at 21:20
Rice was also suggested.wg48temp9 - 1-3-2020 at 05:49
Silica gel cat litter is cheap. Dried first of cause, but does it absorb the alcohol?
I found a paper on the subject :
Attachment: silicagell-davis1930.pdf (293kB) This file has been downloaded 240 times
I will report back when I have read it.
[Edited on 3/1/2020 by wg48temp9]pneumatician - 6-3-2020 at 17:18
from Pop-Sci mag:
has anyone tried it?
I known another method with incredible results, but because nobody believe me, I not reveal the how to. ]:-D
[Edited on 7-3-2020 by pneumatician]
[Edited on 7-3-2020 by pneumatician]SWIM - 6-3-2020 at 17:57
I like potassium carbonate because you dont need to dry it first.
However a lot of these drying agents (including potassium carbonate) aren't all that complete for drying ethanol.
Both the seives and the CaO are very good for single treatments, about as dry as you need for most things.Dr.Bob - 6-3-2020 at 18:18
I have heard that 3A Mol Sieves and aluminum oxide are both good for drying ethanol. They can both be regenerated by heating or heating under
vacuum.
