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Author: Subject: Salting out ethanol and distillation
JJay
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[*] posted on 12-11-2015 at 05:55


I can get phosphoric acid. I guess I could react that with potassium carbonate.
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[*] posted on 12-11-2015 at 09:42


Potassium hydroxide and phosphoric acid are readily available across the globe and are low-cost chemicals, so too is MKP fertiliser (monopotassium phosphate). For the latter, you'd need to react it with an additional two equivalents of potassium hydroxide to yield the required K3PO4.

What I'm very happy about is that now the amateur chemist can easily make their own auto fuel. Converting gallon amounts of a simple distillate into absolute is now a trivial matter of 'bucket chemistry'.

Unfortunately, the current low oil price is not exactly helpful in my green crusade, but I'd be very happy if someone ran their scooter or car on alcohol prepared by this method.

Where's zombie when you need him!



[Edited on 12-11-2015 by deltaH]




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[*] posted on 12-11-2015 at 10:09


I'm simply stunned by this discovery, well done indeed.



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[*] posted on 12-11-2015 at 10:33


Anhydrous CuSO4 works like a charm for drying azeotropic ethanol to (almost) 100% . Just give it a try.
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deltaH
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[*] posted on 12-11-2015 at 10:38


This is taking 37 wt.% to 100% in one step, not just breaking the azeotrope. The cost of CuSO4 for such an endeavor would be prohibitive.

[Edited on 12-11-2015 by deltaH]




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aga
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[*] posted on 12-11-2015 at 11:23


Quote: Originally posted by Starcruiser  
Anhydrous CuSO4 works like a charm for drying azeotropic ethanol to (almost) 100% . Just give it a try.

Cool ! Another method !

Please do the experiment and show the results.

It would be great to see a comparison.

I'll replicate your experiment, then you do the same with mine and let's see if wer're onto something here.

[Edited on 12-11-2015 by aga]




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[*] posted on 12-11-2015 at 11:28


I was surely thinking about a small scale experiment (500 ml or less). I`ve done it, it works. Dryied 95% ethanol with CuSO4 anh. then distilled. Go and try it :)
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[*] posted on 12-11-2015 at 11:32


Then Distilled ?

Have you not read the post containing the experiment ?

Please detail exactly what you Did including the drying of the copper sulphate hydrate crystals.


[Edited on 12-11-2015 by aga]




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[*] posted on 12-11-2015 at 11:51


Very nice results! Maybe you could add 10ml of your ethanol to 0.1 gram of blue CuSO4? I know that absolute ethanol will discolour it, while 99-ish ethanol won't
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[*] posted on 12-11-2015 at 12:02


How would that work Tsjerk ?

Does the copper sulphate need to be 100% dry as well ?

ISTR that it becomes colourless when anhydrous ( no water=no ions) so it'd not be Blue.




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[*] posted on 12-11-2015 at 12:12


The CuSO4 has to be hydrated (blue). Absolute ethanol will dehydrate it to its white state, but it will only do so if it is really anhydrous by itself, making it a nice control for your sample!

Just put a bit in a tube and add the ethanol to be tested to it. If this works and you want to be really sure you could do the same test with your sample but adding a bit (1%-ish) water to the ethanol before adding it to the sulfate.

Edit: this is knowledge from years and years ago... I could have a look if I can reproduce my memories when I get back to the lab tomorrow. We have absolute ethanol, and probably CuSO4 as well. I'm happy I now feel the freedom to do some of my own experiments again! I even go in in the weekends pretending I'm working....

[Edited on 12-11-2015 by Tsjerk]
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[*] posted on 12-11-2015 at 12:12


Quote: Originally posted by aga  
Then Distilled ?

Have you not read the post containing the experiment ?

Please detail exactly what you Did including the drying of the copper sulphate hydrate crystals.


[Edited on 12-11-2015 by aga]


If I`m missing something important, I sincerely apologize (it`s a long topic...).

CuSO4 pentahydrate is readily available and, I think, very cheap everywhere. Drying it is as simple as heating it to 150 C for some time (`till it becomes white-gray). Calculate the amount of H2O needed to get it back to pentahydrate crystallin form and so you will know how much water it can take out from the 95% ethanol. Then, as I said, distill the ethanol, leaving the CuSO4 in the pot.

You can of course dry the pentahydrate again and reuse it countless times.

Perhaps this can be done even with lower conc. ethanol, but I`ve tried it only with 95%.

[Edited on 12-11-2015 by Starcruiser]
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[*] posted on 12-11-2015 at 12:20


What I think Aga is referring to is the fact that his method doesn't need distillation, making it more excessable and less time consuming.
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[*] posted on 12-11-2015 at 12:21


Quote: Originally posted by Tsjerk  
The CuSO4 has to be hydrated (blue). Absolute ethanol will dehydrate it to its white state

Ah. OK.

Will try that.

Will also try with 98% EtOH and see it the effect is different.

Sure would be great to throw this refractometer away and use perceived crystal colours instead ...




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[*] posted on 12-11-2015 at 12:24


Quote: Originally posted by Starcruiser  
If I`m missing something important, I sincerely apologize (it`s a long topic...)

Just read at most this page and the one before of the Vastness of the whole 3 pages and maybe you'd have a clue.

This is NOT a 'long' topic.

25 pages would be start to be called 'long'.

The ability to read, re-read and understand is a key part of any learning process.

[Edited on 12-11-2015 by aga]




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[*] posted on 12-11-2015 at 12:38


Quote: Originally posted by aga  
Quote: Originally posted by Starcruiser  
If I`m missing something important, I sincerely apologize (it`s a long topic...)

Just read at most this page and the one before of the Vastness of the whole 3 pages and maybe you'd have a clue.

This is NOT a 'long' topic.

25 pages would be start to be called 'long'.

The ability ro read, re-read and understand is a key part of any learning process.

[Edited on 12-11-2015 by aga]


I presume It might work even without distillation if this is the challenge. I should just let the anh. CuSO4 in ethanol until it gets fully blue once again. The problem is that I`ve run out for now of 95% ethanol :(

[Edited on 12-11-2015 by Starcruiser]
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[*] posted on 12-11-2015 at 12:40


Buy a bottle of vodka, add K3PO4 to it, then add 5% water to the organic layer and you will have lots of 95% ethanol to experiment with again ;)



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[*] posted on 12-11-2015 at 12:43


Quote: Originally posted by deltaH  
Buy a bottle of vodka, add K3PO4 to it, then add 5% water to the organic layer and you will have lots of 95% ethanol to experiment with again ;)


That`s wise but I`m afraid I will be tempted to use that vodka for more recreational purposes (though I prefer brandy for that matter :))
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[*] posted on 12-11-2015 at 13:01


I think the bit you're missing Starcruiser is that deltaH's process rips all of the water out of Vodka in a way that the Ethanol (EtOH) can be easily separated as 100% (likely near, not exact, +/-1%) from that mixture.

Tripotassium phosphate is also non-toxic, which kinda counts for what people might do with the process.

Copper sulphate IS also insoluble in EtOH, however it's ability to rip the water from the EtOH layer relies almost entirely on the hydration of the copper sulphate, and remains untested.

Do the drying and calculations (everyone here will help if asked) and do the experiment yourself, then post the results.

This is not a Challenge as such, as the only Prize is everybody reading this gains an iota more of Knowledge - we all win no matter how it turns out.

[Edited on 12-11-2015 by aga]




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[*] posted on 12-11-2015 at 14:33


Strange.

If I proposed such an idea and were asked to reproduce the results, i'd positively Jump at the opportunity.

Perhaps i'm free-er to actually Do things than most people.

In the face of Silence i guess it's up to me to actually Do something and then post the results for actual discusson.

I Do wish people would Do more chemistry - the results are far more interesting than repeated speculation with no hard data.




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[*] posted on 12-11-2015 at 15:45


Aga, this really is an amazing result if you can get it confirmed. I don't doubt the results you're getting from your refractometer, but the 100% ethanol value needs to be verified.
I would not expect K3PO4 to be able to do this separation, and I don't think the dehydration of ethanol like this to be thermodynamically favourable.

But that's just my own thinking; unexpected results make things interesting! Maybe here's a practical confirmation test: Try to dissolve a few milligrams of potassium permanganate in your ethanol. Anhydrous ethanol should remain colourless. The more colour, the more water. If calibrated, the test could be made quantitative. Using a spectrophotometer would be best, but even a test tube to test tube colour comparison should work well.
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[*] posted on 12-11-2015 at 21:40


Besides salting out ethanol, I've been trying to think of other applications for K3PO4's salting out capabilities.

I found a paper (attached) that investigated the salting out of ionic liquid solutions from water using K3PO4, which is an impressive feat since it's a fellow ionic compound it's forcing out.

Attachment: Salting out of ionic liquids.pdf (2.8MB)
This file has been downloaded 144 times

Truly K3PO4 must be 'King of Salts' :D

Perhaps it might be used to regenerate choline chloride based deep eutectic solvents (DES) which got diluted with water?

Or even preparing them when all you have is the readily attainable and low cost 70-75% solutions of choline chloride, i.e. dissolve your ethylene glycol/malic acid or whatever else you wish to use as a hydrogen bond donor or a metal salt hydrate, e.g. ZnCl2, into 70-75% choline chloride solution and then saturate with K3PO4 and decant off the DES.

That would simplify the preparation of DES's for the amateur chemist significantly if it would work.

You need K3PO4!.png - 900kB

Who would have thought? :o

I'm officially renaming absolute alcohol derived from K3PO4 to...

kapow.jpg - 46kB

or KA-POW! if you prefer.

[Edited on 13-11-2015 by deltaH]




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[*] posted on 12-11-2015 at 23:26


For those not yet clear on this, there's a big difference between salting out and desiccation. Using an anhydrous salt that wants to form a hydrate is a type of desiccation. It's a solid-liquid system and absorbs stoichiometric amounts of crystal water.

Salting out is a liquid-liquid or biphasic liquid equilibrium, it is non-stoichiometric and you need much less salt to achieve large changes in concentration.







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[*] posted on 13-11-2015 at 04:17


anyone know what a "multipleeffect evaporator" is?



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[*] posted on 13-11-2015 at 06:46


Unfortunately the cheap phosphate fertilizer I see is ground-up phosphate rock. Buying monobasic potassium phosphate for conversion to tribasic is still like $7 per pound. I don't think this is any more efficient than the potassium carbonate method. You could convert K2CO3 to the phosphate with acid.

Where are you getting your fertilizer?




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