Can you get rid of alcohol in water (without keeping it)?

[Jack Cheney]

Hello. My name is Jack. New member to the forums. Nice to meet you all!

I have a general question that is part of a project I am working on for graduate school. I'm looking to distill water through solar energy in a closed solar still and am in a pickle finding a way to prevent alcohol from boiling and condensing back into our distilled water.

Naturally, alcohols and similar substances have a lower boiling point so they'll evaporate before the water does in our experiment. However, what does one do in order to get rid of or absorb the alcohol such that it doesn't collect with the water? Does alcohol "attach" to anything in particular that can act as a filter?

Any help or ideas that may give me a push down the right direction is appreciated. Thanks!Jack Cheney

 

[rootone]

You could heat the alcohol-water mixture so that the temperature is great enough for the alcohol to evaporate easily, but is less than the evaporation temperature for water.
I won't be 100% efficient, some water will be lost, but the result will be considerably less alcohol % in the remaining solution.

You could also freeze your starting liquid then crush it up into sludge, and very slowly let it thaw.
The alcohol will liquify and run out of the sludge before the water does.

If your system is completely closed though you can't do either of these because by definition you can't extract some part of it into another system.

 

[SteamKing]

Hello. My name is Jack. New member to the forums. Nice to meet you all!

I have a general question that is part of a project I am working on for graduate school. I'm looking to distill water through solar energy in a closed solar still and am in a pickle finding a way to prevent alcohol from boiling and condensing back into our distilled water.

Naturally, alcohols and similar substances have a lower boiling point so they'll evaporate before the water does in our experiment. However, what does one do in order to get rid of or absorb the alcohol such that it doesn't collect with the water? Does alcohol "attach" to anything in particular that can act as a filter?

Any help or ideas that may give me a push down the right direction is appreciated. Thanks!Jack Cheney

It's not clear what alcohol is doing in your apparatus in the first place.

Are you making 'shine and looking for advice on how to get it distilled properly?

 

[Borek]

Single step distillation will never separate them. Besides, it is not possible to fully separate them at all with distillation. Are you aware of the fact alcohol and water make an azeotrope?

 

[Jobrag]

I hope that I don't fall foul of guidelines here, but if the alcohol water mixture is one that isn't detrimental to human health could you pass the liquid through your body and then distill the waste product?

 

[rootone]

Much of alcohol consumed is metabolised in our body into other chemicals, such as acetic acid and acetaldehyde, which then go on to get involved in other body chemistry.
If the person has drank a considerable amount then some alcohol will be passed out in urine, along with other toxic waste products.
You could in principle extract that alcohol, but it will be far less than the amount the person had consumed and the process of completely eliminating other toxins could get difficult as some of them are soluble in alcohol.
Distilling the urine of drunk people to produce more alcohol is not a practical proposition at all.

 

[Jack Cheney]

Thank you so much for your feedback fellow posters!

Just to clarify, no we DON'T want to keep the alcohol in any way. We want pure water as the final result. Any way to get the alcohol to disappear completely from the final water collection within the confines of our project design is what we desire.

As a mechanical engineering bachelor, I'm only elementary when it comes to chemistry (though I am learning a lot through this project). I have never heard of an azeotrope so I looked it up and I see what you're saying. If they are considered thoroughly mixed than solutions like this will be better off boiling off the alcohol by itself first before actually distilling the water. Even then it's not guaranteed we'll lose all of the alcohol.

Since we're dealing with the randomness of the sun it seems this alcohol cannot be "automatically" removed if we were to just leave the mixture out in the sun all day. I was hoping some "filter" in the mixture (a solid material or a liquid added) would convert alcohol into some form of solid waste or be kept from leaving the chamber (like heavy metals or salts will), but perhaps I am hoping for too much.

...And just to clarify no urine is to be involved in this project.

Thanks so much for your feedback. If there's more ideas for this I deeply appreciate the feedback and the knowledge.

 

[SteamKing]

You haven't said how the alcohol got into the system in the first place. I still suspect you're cooking corn mash or something similar, trying to make student hooch.

"Solid alcohol". You really are unfamiliar with chemistry, at least the non-cryogenic kind.

 

[Jack Cheney]

It's not a specific mixture per se. There is NO desire for alcohol as a by-product I swear!

See, the objective is to use nanomaterials that facilitate heat transfer to distill water with solar heat in as many different situations as possible. The best example of a sample would be one that is obtained from a third world country river where the water is polluted (either by humans or some natural pollutant such as poor minerals or parasites). Alcohol is just one of many contaminants that could be in water that is hard to remove (that's why I'm here to learn about if there is a way).

(Maybe I should have suggested something else mixed with or in water. Would chloroform be a better example than ethanol?)

I'm not saying the alcohol itself will be "solid." I probably phrased that wrong. What I meant was a way to mix/convert an alcohol mixture such that you obtain water and some solid particulate.

Alcohol + some filter/converter = H20 + solid

Something along those lines. It doesn't have to convert to straight water but something that is not a problem for humans even if it's in distilled water.

I work in a laboratory where we are making nanomaterials. My research into this particular problem has been difficult since I don't have a focused education on fluid chemistry.

 

[SteamKing]

Distillation of water is a very energy-intensive process, due to the relatively high specific heat of water. Adding on a water purification feature adds to the complexity.

Alternate technologies, like reverse osmosis, are being developed because you don't have to use as much heat to desalinate/purify wastewater into a potable product.

https://en.wikipedia.org/wiki/Reverse_osmosis#Water_and_wastewater_purification

 

[Jack Cheney]

Distillation of water is a very energy-intensive process, due to the relatively high specific heat of water. Adding on a water purification feature adds to the complexity.

Alternate technologies, like reverse osmosis, are being developed because you don't have to use as much heat to desalinate/purify wastewater into a potable product.

https://en.wikipedia.org/wiki/Reverse_osmosis#Water_and_wastewater_purification

That's why we're using a fresnel lens to concentrate our heat onto a specific area within a cylindrical test chamber. This is a concentrated heat source project. The material we're using also facilitates solar absorption (based on both experimental and modeling research). We're actually basing our setup on another project that didn't incorporate collecting the water so that's why I'm looking for advice on getting rid of the contaminant in the mixture.

 

[Borek]

Removing alcohol and purifying water are two different things (even if the former is definitely a part of the latter). I would start checking what technologies exist/are used for water purification, after all it is a common task throughout the world.

 

[Jack Cheney]

This is probably why it's so hard to find anything that discusses this process (both in academic search or through google). When I say "I want to distill alcohol out of water," it's assumed I want to keep the alcohol when I really want to get rid of it. For us, distill = purify so pardon the nomenclature. We want safe, clean, distilled drinking water that we process out of dirty water. It HAS to be solar powered as this is what our funding is geared towards (this is based on a grant-funded proposal).

I will continue checking more means of water purification to understand it better, but if that's not what I actually want (we want to distill it), then I need to figure out something else.

Thanks again Borek.

 

[rootone]

Removing alcohol and purifying water are two different things (even if the former is definitely a part of the latter). I would start checking what technologies exist/are used for water purification, after all it is a common task throughout the world.

Restricting the power source to direct solar heating is going to be a serious limitation for some of these technologies though.
Even the reverse osmosis method which is a lower energy process requires some pumps.

 

[Borek]

We want safe, clean, distilled drinking water that we process out of dirty water.

Google for sun powered water distillation, sun powered desalinators or emergency desalination. While these are never designed to get rid of everything, that should definitely give you some ideas to work on.

 

[Almeisan]

Best way to remove organic molecules from water is to use UV radiation and a source of free radicals/H2O2/O3 and just oxidize any carbon compound into CO2.

Most obvious way to purify water is through reverse osmosis. That's why all you will ever find about distilling alcohol/water mixture is preserving the alcohol. If you want to preserve the water, you wouldn't bother. While it is indeed possible to distil for drinking water, one wouldn't ever come up with an engineering solution to do so. Boiling is as far as one can pratically go, unless of course you have an innovation.

Anyway, how much ethanol have you measured? Even if you use some method to actually remove ethanol molecules, you need to do the same independently for any other substance with similar boiling point that can theoretically be in your wastewater.
Haven't heard of ethanol-contaminated water sources killing people. You sure this is something you worry about?

 

[rootone]

Best way to remove organic molecules from water is to use UV radiation and a source of free radicals/H2O2/O3 and just oxidize any carbon compound into CO2.

Interesting, yes that would be a good way to destroy/remove organic molecules generally, ... and highly focused sunlight *might* have enough UV in it to have a noticeable effect.

Haven't heard of ethanol-contaminated water sources killing people.

Well there are cases of extreme alcohol consumption leading to death directly though poisoning, body chemistry goes dysfunctional -> heart attack etc, but that's another matter.

 

[epenguin]

I would have thought the concentration of alcohol in third world rivers never so high need worry about it for your project.
Nor even in first world rivers, not even in Dublin.

 

[Jack Cheney]

I would have thought the concentration of alcohol in third world rivers never so high need worry about it for your project.
Nor even in first world rivers, not even in Dublin.

Again, it's not exactly alcohol that's the concern. It's aqueous solutions where part of the mixture has a lower boiling point that water. Bespenol is another example or gases like nitrogen and chlorine.

We actually moved along with the project a bit more. It turns out activated carbon might be our best as a distillation "filter" where the gases and other pollutants can be adsorbed by the carbon. Titanium Oxide also helps in adsorbing and degrading alcohols with sunlight (this is of course based on academic journal sources I was finding).

Appreciate the feedback from all of you.Jack Cheney

 

[thankz]

http://www.sciencedirect.com/science/article/pii/037673889280149E

 

[Jack Cheney]

http://www.sciencedirect.com/science/article/pii/037673889280149E

I had to ask my school to request this since we don't have it in our journals, but thanks for the source! Yeah, that's more what I'm talking about. The math here might prove useful even if it's not the same material we'll be using as them.

 

[epenguin]

I did not know what bespenol is so I googled it and no one else does either.

You seemed to say you are after something safe for humans, e.g. drinkable water? I would have thought there was nothing in even polluted river water more volatile than water that would be a problem. And that the idea is using free sunlight smartly in a economical process, but if you are going to start throwing in activated charcoal or titanium oxide the economy vanishes.

 

[Jack Cheney]

I did not know what bespenol is so I googled it and no one else does either.

You seemed to say you are after something safe for humans, e.g. drinkable water? I would have thought there was nothing in even polluted river water more volatile than water that would be a problem. And that the idea is using free sunlight smartly in a economical process, but if you are going to start throwing in activated charcoal or titanium oxide the economy vanishes.

That was a typo. I meant to say bisphenol.

https://en.wikipedia.org/wiki/Bisphenol_A

VOCs, nitrogen, chlorine, and organics are a concern that aren't necessarily taken out of water through solar distillation and UV radiation (we also don't want to release them in the air).

This project is a solar distillation test chamber where the water is captured in a closed environment. My primary concern was any gases or pollutants that would leave with the steam and recombine with it or get released outside. We want to minimize pollutants in whatever way possible.

Since this project is specifically for nanomaterial research, yes we are adding in materials that will float on the water and make heat transfer easier. Adding in activated carbon would only one of three layers that are already planned so economy is already affected by this. Besides, activated carbon is cheap. It comes from many sources!

Maybe this wasn't the right forum to post these questions. There's no getting around certain specifics for this project. It's solar distillation with a composite material floating on top of the water facilitating heat transfer. It's multiple layers of different materials that we got grant-funding for and that will contribute towards a thesis I am writing for my Master's degree. The water is collected inside a box we are building for testing.

My primary goal posting on here was to get some ideas for filtering out more pollutants, not to simplify the project more. I appreciate those that have posted interesting ideas such as the membrane article.

 

[epenguin]

Well your link gives 220° for boiling point of bisphenol so that shouldn't be in your distilled water.

 

[Jack Cheney]

Well your link gives 220° for boiling point of bisphenol so that shouldn't be in your distilled water.

Correct, so that would be something that remains in the test chamber, but gases like chlorine and nitrogen have a lower boiling point and so, in a close environment, would vaporize and then condense again back into distilled.

I had not check bisphenol's boiling point so that was my mistake but it is just one of many things that carbon filters are used for so I popped that out on the top of my head. Think more along the lines of lower boiling point pollutants then and you'll see what I'm dealing with.

 

[epenguin]

Correct, so that would be something that remains in the test chamber, but gases like chlorine and nitrogen have a lower boiling point and so, in a close environment, would vaporize and then condense again back into distilled.

I had not check bisphenol's boiling point so that was my mistake but it is just one of many things that carbon filters are used for so I popped that out on the top of my head. Think more along the lines of lower boiling point pollutants then and you'll see what I'm dealing with.

There needs to be someone in your team with more knowledge of chemistry. They would tell you the atmosphere is already so very polluted with nitrogen you surely would not make a difference.

I'm joking. Perhaps you mean oxides of nitrogen, and perhaps you mean not chorine but chlorides? Actually I find it difficult to think of any volatile substance in river water likely to be a problem even if your project is very successful.