How to Remove Water From Isopropyl Alcohol

[Tony]

I have always been looking out for information on how to do this. I thought I'd pass it along to see if anyone had any thoughts.

Tony

How to Remove Water From Isopropyl Alcohol

You can separate isopropyl alcohol and water using heat and a distillation apparatus. Since isopropyl alcohol has a lower boiling point than water, you can bring it to a boil without boiling the water in it. Different boiling points are the key characteristics that allow liquids to be separated in the process of distillation. The result of this process will be pure water and pure isopropyl alcohol. You should perform this procedure in the safety of a laboratory equipped for chemistry and only while wearing appropriate safety gear, which includes goggles, gloves, long pants and a long-sleeved shirt.

Difficulty: Moderately Easy
Instructions
Things You'll Need:
Bunsen burner
Tubing
Distillation flask
Collection flask
Small bags of ice
Protective goggles, gloves and clothing
1
Set your distillation flask over the Bunsen burner. Run the tubing with a downward slant from the distillation flask to the collection flask. Affix small bags of ice to the tubing to cool it down.

2
Place the isopropyl alcohol into the distillation flask and turn on the Bunsen burner. Any isopropyl alcohol that is not 100 percent alcohol is partly water. For instance, you can buy small bottles of 70 percent isopropyl alcohol from most pharmacies. The contents of those bottles are 70 percent isopropyl alcohol and 30 percent water.

3
Use a low flame from the burner to slowly heat up the flask. The boiling point of isopropyl alcohol ranges from 176 to 181 degrees Fahrenheit, which is about 35 degrees less than the boiling point of water. The alcohol will boil first.

4
Watch carefully for the first sign of boiling. When you see it, reduce the flame from the Bunsen burner so that the boiling stays at a simmer. When the solution is at this temperature, it will be the isopropyl alcohol that is boiling, not the water.

5
Let the solution boil until it stops. When the boiling ceases, all of the isopropyl alcohol will have been removed from the water and will be condensing in the collection flask. Allow the entire apparatus to cool before handling the flasks.

[Joe Farina]

Hi Tony. Looks too complicated, for me. Someone once suggested using a water-absorbing desiccant (which doesn't absorb alcohol) and simply throwing these into the IPA/water mixture. I assume the desiccant would be something like Drierite crystals, though I never tried doing it. I would filter the IPA afterwards, since some particles from the desiccant would probably get in. The Drierite can be recycled by baking to remove the water.

[Johnfp]

Yes, we did talk abou this and the consensus was to use the desiccant. From what I remember, using the distillation process will not get you near 99%. But you can with the desiccant. And yes, I do believe it was Drierite.

Here is and idea. Have a small cheese cloth bag of the stuff in your 99% at all times. Every week or so take it out and microwave it till dry and reuse.

[Tony]

Thanks guys, I remember this from the old forum.
I was worried about unintended contamination of the IPA. Also I am guessing the blue indicating Drierite would not be used?
Sometimes I get a strange film in my final hologram which I can only guess is some contaminate getting on there and baking on.
I filter my chemicals after 3-4 sessions but I still manage to get smears.

[Joe Farina]

Have a small cheese cloth bag of the stuff in your 99% at all times.

That sounds good. I suppose it could even be a bag of fine filter material, to avoid contamination in the first place. McMaster-Carr has lots of filter material in large sizes (not paper, but polymer and metal). If the blue in the Drierite is soluble in alcohol, it may be better to use another type of Drierite, there are lots of different types available, I think some of them lack the blue coloring.

[Joe Farina]

I forgot about coffee filters, they are big and cheap enough to use several layers.

[Tony]

I have not been about to find any method on line that usings Drierite to dehydrate IPA.

[Joe Farina]

I think the person on the old forum actually used silica gel crystals, the stuff in the little bags that keeps moisture away from consumer products.

[Joe Farina]

Tony, I did a quick search on the old forum. In the search box, I typed: silica gel IPA

I got one result in the thread "the greenies, blueies, and violeties" in which Jeff Blyth gave instructions for using silica gel. He said these must be very thoroughly baked, and as soon as the baking is completed, they should be used right away, before they have a chance to absorb ambient humidity. Just go to the old forum by using the link Colin provided in the Administration section of this forum, type in those keywords in the search field, and you will find a lot of information. It would be very nice to have a method worked out for doing this.

[Joe Farina]

I'm still trying to jog my memory on this subject. Jeff was talking about using the silica gel to remove the water from a gelatin layer I think. But there was another person, not Jeff (maybe it was on Network54), who definitely used silica gel to remove the water from IPA/water, but I haven't been able to find the post yet.