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Topic: Oil and water with a twist...  (Read 7110 times)

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Offline Hallin

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Oil and water with a twist...
« on: February 15, 2008, 05:58:59 AM »
Hi!

I'm looking for two liquids (or solids that are liquids above 150°C) that are stable liquids, without to much vapourising in a temperature range of 180-240°C. Also I want the two liquids with different density. Let's say one approximately 1,5 kg/dm³ and the other approximately 0,9 kg/dm³, and if you mix them I want them to separate like oil and water and stay stable in that condition.

Is this possible and if so, what substances am I looking for?

Best Regards!

Mathias
Sweden


Offline azmanam

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Re: Oil and water with a twist...
« Reply #1 on: February 15, 2008, 08:20:25 AM »
have you considered ionic liquids?
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Offline Hallin

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Re: Oil and water with a twist...
« Reply #2 on: February 15, 2008, 09:50:57 AM »
Forgive my ignorance, I'm no chemist. I am a confused mechanical engineer and kind of a novice when it comes to chemistry.  :P

Ionic liquids you say, what does that mean more specific. Can you give me examples of what liquids you have in mind?

Thanks a lot!

/Mathias

Offline azmanam

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Re: Oil and water with a twist...
« Reply #3 on: February 15, 2008, 10:06:11 AM »
Ionic liquids are ionic salts (think table salt, sodium chloride, which melts above 800 oC), but Ionic liquids are special in that they melt near or below room temperature.  They also have negligible vapor pressure (i.e. "without too much vaporizing")

You can see a report I did on them here

http://www.unc.edu/depts/mtcgroup/litmeetings/ionicliquids.pdf

The beginning is some background and an OK primer, the last slide has some of the references I used.

They're mainly used now as "green" solvents for organic synthesis, but I think they might fit your separation requirements nicely (depending on the specific application). 

More info

http://en.wikipedia.org/wiki/Ionic_liquid
http://www.organic-chemistry.org/topics/ionic-liquids.shtm
http://www.chemsoc.org/ExemplarChem/entries/2004/bristol_vickery/ionic_liquids.htm
http://www.iupac.org/publications/pac/2000/pdf/7207x1391.pdf
http://www.sigmaaldrich.com/catalog/search/TablePage/16255866

You'll probably want 1 ionic liquid and one high boiling hydrocarbon solvent (DMSO comes to mind, but watch out for safety hazards (MSDS - https://fscimage.fishersci.com/msds/07770.htm).  Xylenes also comes to mind, but the boiling points may be too low for your application (wikipedia - http://en.wikipedia.org/wiki/Xylene)
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Offline Hallin

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Re: Oil and water with a twist...
« Reply #4 on: February 20, 2008, 02:51:36 AM »
Thanks a lot! I will definitly look in to this, though it sounds tricky with the safety hazards with the low density fluids.

My first thought as a novice was to use som kind of oil as the light fluid, is there any kind that could fit these properties or is this an idea that I should drop and move on?

Offline azmanam

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Re: Oil and water with a twist...
« Reply #5 on: February 20, 2008, 06:24:13 AM »
Oil's certainly fine.  Some mineral or silicon oil will probably be stable in your temperature range.  Water won't stay a liquid that hot.  And if you use two oils, I'd be worried they'd be soluble in each other - even if the densities are different - and they won't separate at the end.  You may also want to look into to perfluorinated hydrocarbons.  I don't know much about them, but they tend to be immiscible with water and standard organic solvents.
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