[Fresco]

Hello everyone,
I have a very simple question, I'm a novice so hopefully I dont bore you with what I ask:

I have dissolved a herbal powder in a water/ethanol liquid.  Its about 5 grams of herb powder in about 100 ml of 50/50 v/v ethanol and H2O.  I used Vodka instead of having to go through the hassle of having to buy ethyl alcohol.

Now I want to evaporate the alcohol so as to leave just mostly H2O.
The easy way of course is to boil it at about 80C, this will get rid of most alcohol.

But my question is there another way to remove the ethanol from the water without evaporating??

[nj_bartel]

Pretty sure that'd be the easiest way by far.

[Fresco]

What about a centrifuge???

[nj_bartel]

I could be wrong, but I don't believe centrifuging works with 2 completely solvated substances.

[Fleaker]

It does not. Centrifuging in the sense we speak of here will only work between two different phases, each having a different density.
Ethanol and water are fully miscible.


Are you familiar with azeotropes? Ethanol and water form a minimum boiling azeotope. This means that no matter how many times you evaporate off the alcohol (distillation) you will never remove all of the water contaminate. The water must be removed through another physical process (or even chemical process, CaO is used for removing water from azeotropic EtOH).

This means that when you set it out to evaporate, some of the water will coevaporate with the ethanol. Your objective is to remove the ethanol and leave the water, right? Why can't you simply add more water?

[ARGOS++]

[JGK]

With a sample of that size (100 mL) evaporation is going to take forever. Centrifugal evaporation may be quicker but you will have to subdivide your sample into smaller aliquots.

Have you a rotary (vacuum) evaporator in your Lab?

[Fresco]

It does not. Centrifuging in the sense we speak of here will only work between two different phases, each having a different density.
Ethanol and water are fully miscible.


Are you familiar with azeotropes? Ethanol and water form a minimum boiling azeotope. This means that no matter how many times you evaporate off the alcohol (distillation) you will never remove all of the water contaminate. The water must be removed through another physical process (or even chemical process, CaO is used for removing water from azeotropic EtOH).

This means that when you set it out to evaporate, some of the water will coevaporate with the ethanol. Your objective is to remove the ethanol and leave the water, right? Why can't you simply add more water?

I'm not at all familiar with azeotropes???

As far as boiling off the ethanol, its OK if a little bit of ethanol is left in the water, I just cant have too much of it or I'll get drunk when I wanna consume the herb tincture.

If I leave the water/ethanol mixture stand overnight without lid, how much of the ethanol will have been evaporated by morning, does anyone know?? (lets assume time elapsed was 24 hrs, and the mixture was 100 ml water and 100 ml ethanol v/v)

[nj_bartel]

I think you know what an azeotrope is, you just don't know the term, as you mentioned that you couldn't get rid of all the ethanol by boiling.  An azeotrope is a mixture of two substances that has a singular boiling point.

[Arkcon]

Short answer:  That takes a long time, and may never finish.

Longer answer:  Water and ethanol form an azeotrope.  They combine and leave the vapor phase together.  You lose ethanol form a water solution only (about) as fast as you lose water.  That is slow, because water binds strongly to itself.  It may well take days, and you will attract much dust, in that time, if you leave the vessel open.

Geek answer:  If you have access to a lab, you may try freeze-drying, or vacuum evaporation to speed the process up, with minimal heat damage to the active.  We do not have DIY procedures for the removal of ethanol from solutions.  This is, in fact, a very hard problem to fix.  If you could save the evaporated ethanol, this would be concentrating it, and that is bootlegging.  Yes, you don't want to save it, for this particular application, but the techniques are the same.  It is hard to achieve, and various government agencies like it to be difficult.  So it works out well -- for them, not you.

[Fresco]

Short answer:  That takes a long time, and may never finish.

Longer answer:  Water and ethanol form an azeotrope.  They combine and leave the vapor phase together.  You lose ethanol form a water solution only (about) as fast as you lose water.  That is slow, because water binds strongly to itself.  It may well take days, and you will attract much dust, in that time, if you leave the vessel open.

Geek answer:  If you have access to a lab, you may try freeze-drying, or vacuum evaporation to speed the process up, with minimal heat damage to the active.  We do not have DIY procedures for the removal of ethanol from solutions.  This is, in fact, a very hard problem to fix.  If you could save the evaporated ethanol, this would be concentrating it, and that is bootlegging.  Yes, you don't want to save it, for this particular application, but the techniques are the same.  It is hard to achieve, and various government agencies like it to be difficult.  So it works out well -- for them, not you.

Thanks for this, thats interesting.

I think I solved the problem, I boil off the ethanol but at around 90 Celsius, this is not boiling the water and hopefully doesnt destroy the herbs.
Another solution is use a water/glycerin solvent. The glycerin you can drink.
Only problem with that *sigh* is the vegetable glycerin doesnt dissolve all the herbs constituents very well