Tried dehydrating ethanol?

[ignesandros]

I googled "dehydrating ethanol" and came up with a few good articles, such as this JTF article suggesting corn meal would be an energy-effective way of rendering nearly 200 proof ethanol. I independantly wonder if silica gel, which is fairly cheap nowadays, would also absorb water vapor but not ethanol vapor. If this was the case, one could direct the still vapors through an interchangeable cell-style silica "water-filter". The water could then be baked off using a fraction of the produced ethanol, waste heat from another process, a solar oven, or some other efficient technique. This would result in much higher % ethanol and maybe even allow itself for use in biodiesel production instead of more toxic and expensive methanol.

-Andrew

[richhagen]

If I recall from a lab class many years ago, we used an ionic salt that had a hydrated form to adsorb the water out of the ethanol.  Somthing like copper sulphate might work, in that it has a hydrated form when exposed to moisture.  Sufficient heating of the crystals would drive off the water, and then the salt could be re-used.  Ideally, the salt chosen would be insoluble in ethanol, and would be harmless for the end use. One would batch distill to the Azeotropic state and then add sufficient anhydrous salt to absorb the moisture present.  The salt would be filtered out and heated to drive off moisture and the cycle repeated.  It is not energy efficient, and I just checked and saw online that most commercial plants now being built are using vapor phase separation with a zeolite used for absorbtion of the moisture with a pressure swing cycle to rejuvenate the zeolite.  The reason cited is that it is less energy intensive.  Rich Hagen  

[Kwazai]

somewhat off topic-

I took some jim beam and put it in a closed container and added about a teaspoonfull of extra virgin olive oil (.79sg) and was able to seperate(overnight) the alcohol out of the whiskey. would this also have 'dehydrated' the alchohol?

perchance is their something cheaper than extra virgin olive oil?(.79sg or better)

[Bruce S]

Sorry , dry alcohol with oil will not work.

When trying the dry alcohol , which is trying to remove the last bit of water to up the proof, the best method is the use of a descant. Salts are good as they are reusable. Enough of those neat little packets of silica will do the same, then you merely need to dry them using solar heat or something similar.

The silica or better Zeolite, will also have the added effect of making it non-drinkable.

Hope this helps

Bruce S

 

[finnsawyer]

How about quick lime?  It might be ideal for the home experimenter.  You can make it from chalk by heating the chalk.  When you add water it takes in the water and releases heat, which might further help the process by evaporating the alcohol, which can be condensed in a still.  Of course, maybe it would also combine with the alcohol, which has that OH end sticking out.

[richhagen]

It appears that it is used for this purpose along with potasium carbonate and calcium chloride.  An interesting article on the subject is here:  http://journeytoforever.org/biofuel_library/Mariller.html

Rich

[ignesandros]

I hadn't meant for the desicant to be mixed in, but I suppose that's a possibility. Producing your own quick lime, btw, is actually dangerous and isn't as cost effective as buying it ready-made from a building supply house.

-Andrew