How to Remove Water From Isopropyl Alcohol

Dichromated Gelatin.
Joe Farina
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Joined: Wed Jan 07, 2015 2:10 pm

How to Remove Water From Isopropyl Alcohol

Post by Joe Farina »

OK, I found it, it was from Network54, and the thread is called "Recycling Alcohol thought"

About the 10th post down is by Tom M and says "I use silica gel in the alcohol to absorb water. Filter out the silica and bake it to remove the water and reuse the stuff. Never tested the % after this but "they" tell me it's very close to 100%"
Tony

How to Remove Water From Isopropyl Alcohol

Post by Tony »

Thanks a lot Joe,
I still have not found a independent source for dehydrating IPA using silica gel.
I have no doubt Jeff is right and maybe it is worth a try.
I will poke around somemore

Tony
Joe Farina
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Joined: Wed Jan 07, 2015 2:10 pm

How to Remove Water From Isopropyl Alcohol

Post by Joe Farina »

So far I'm only seeing some indirect references to it on the web, nothing really solid. There is some interesting information on "salting out" IPA at http://www.instructables.com/id/How-to-Salt-Out/
dannybee
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How to Remove Water From Isopropyl Alcohol

Post by dannybee »

Joe Farina wrote:So far I'm only seeing some indirect references to it on the web, nothing really solid. There is some interesting information on "salting out" IPA at http://www.instructables.com/id/How-to-Salt-Out/
yes I have done both methods, they work very well, altho you will never get IPA totally 100% by its very nature it will want to draw water out of the air :D
a_k
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Joined: Thu Jan 15, 2015 10:52 pm

How to Remove Water From Isopropyl Alcohol

Post by a_k »

I have used anhydrous copper sulfate crystals to desiccate ethanol and isopropanol. It would not be suitable for 70% solutions, but if you have 95% ethanol or 99.x% isopropanol, the procedure works ok.

CuSO4 is not soluble in alcohol, the crystals can be simply filtered off and reused after drying with heat to drive off the crystal water. Anhydrous CuSO4 is off white and when it absorbs water the colour turns to blue, which indicates when it is is time to dry it again.
Paulos
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Joined: Thu Jan 08, 2015 11:46 am

How to Remove Water From Isopropyl Alcohol

Post by Paulos »

Gypsum plaster, a building and modeling material, would likely dehydrate IPA. As building material it is easily available and very cheap.
Gypsum plaster is "Calcium Sulphate hemi-hydrate".
Pour some plaster powder in the IPA bottle, shake well and let them react. 290 g plaster will absorb 54g water:
2 (CaSO4·1/2H2O) + 3 H2O→ 2 (CaSO4·2H2O)

Also "Lime plaster" (calcium oxide) and "Cement plaster" are potential desiccants.

( http://en.wikipedia.org/wiki/Calcium_sulphate .....reacts slowly with water to return to the dihydrate state, a property exploited in some commercial desiccants.)
http://en.wikipedia.org/wiki/Calcium_oxide
http://en.wikipedia.org/wiki/Plaster

It is worth to give them a try.
holorefugee

How to Remove Water From Isopropyl Alcohol

Post by holorefugee »

I have a few tons of pharmaceutical grade Gypsum. It costs me about $.35 per pound when I order a pallet of 50# sacks. PM me if you want a sample. If you wanted to run down that road I think slaked lime would work. Or perhaps Epsom...

A much easier way would be to use freeze distillation. I don't think you can get to 99% but it would help a lot. Just take a beaker of IPA and freeze it in your freezer. The water will freeze first and make a film on the top. Break this out and you have removed much of the water. "Jacking" cider is done this way in the North East.
a_k
Posts: 190
Joined: Thu Jan 15, 2015 10:52 pm

How to Remove Water From Isopropyl Alcohol

Post by a_k »

Would the freezing out work with IPA? I'm using IPA as a windshield cleaning fluid specifically to decrease the freezing point in winter. The water/IPA mixture remains liquid, depending on the IPA concentration, down to very low temperatures.
holorefugee

How to Remove Water From Isopropyl Alcohol

Post by holorefugee »

Hmmm, I know it works for ethyl alcohol. I'll try and post.
jnhong

How to Remove Water From Isopropyl Alcohol

Post by jnhong »

holorefugee wrote:Hmmm, I know it works for ethyl alcohol. I'll try and post.
At what temperature does ethyl start to separate from water? The vodka in my freezer doesn't mind the cold so much.
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