Sciencemadness Discussion Board - How to extract ethylene glycol from car liquid

How to extract ethylene glycol from car liquid

pbmineral - 6-8-2007 at 12:39

Hi,
I recently heard that r"efreshment liquid for cars" (excuse me I don't have exact translation) was made up of ethylene glycol (20 to 50%) but it's mixed with water and others. I wondered if it was possible to extract it and how to do it.
I tried with CHCl3 it seems it worked but extracted very few.

Do u think I could use other solvants to get better results ?

Thanks

Peter

Nicodem - 6-8-2007 at 12:52

You can get antifreeze with ethylene glycol content up to 95% (at least where I live). You can not use extraction as a method of purification for ethylene glycol since its partition coefficient is unfavorable for any solvent you might try. When I needed ethylene glycol I just went to the store, bought the antifreeze with the highest concentration declared on the label and distilled it under aspirator vacuum (you need to use magnetic stirring as well else ethylene glycol bumps terribly during vacuum distillation). You can also distill at atmospheric pressure (but use an air cooled condenser) but given the b.p. of ethylene glycol this is not very practical. There are some additives in most if not all antifreeze formulations that remain in the flask so do not distill to dryness or they might start decomposing and contaminate your distillate. These are actually the only reason why you need to distill it.

Ozone - 6-8-2007 at 14:40

Why not run the antifreeze through activated carbon (a shake flask will usually do as well) at 60-80°C. This should remove the (primarily) fluorescein. Then, either rough dry (sodium or mag sulfate) or azeotrope the water out ( with or without vac.; it should be a minor fractional component). Fine drying can be done easily (and without side reaction) using molecular sieves (4A, IIRC.).

Cheers,

O3

S.C. Wack - 6-8-2007 at 14:53

The antifreeze here has lots of crap in it - salts, other glycols. Distillation is the only way, and more than one condenser is recommended if simple distilling. Captain Obvious says: "That shit's poisonous!". I would say that simple distillation is practical as long as you keep an eye on the temperature of the distillate. A second and preferably fractional distillation will be necessary if purity is important, with the stuff we have here.

BromicAcid - 6-8-2007 at 15:08

Yeah, you can get the pre-diluted material and that has ~50% water in it, however you can also buy the undiluted material, some are propylene glycol, some ethylene glycol and they all seem to have some (5% tops) diethylene glycol and corrosion inhibitors. A couple members of our board had good success distilling it, check out the thread on EGDN.

DeAdFX - 6-8-2007 at 15:11

... I distill mine. The highest concentration at the hardware stores is 50/50 prediluted. When distilling this stuff there is shit that comes over at ~110C which I assume is mostly water. I find this odd cause another thread on this the poster mentions his stuff just comes over at 197C... After the ~110C stuff comes over I get something that boils at around 185C+. which is 12C short of the boiling point of ethylene glycol... I guess this stuff forms an azetrope or I am just not putting enough heat or something:rolleyes:

I would recommend using a water cooled jacket to distill this stuff other wise your condensor/collector is going to be filled with a white mist.

[Edited on 6-8-2007 by DeAdFX]

pbmineral - 6-8-2007 at 15:12

ok thanks for so many answers !

@Nicodem re: distillation

chemrox - 18-8-2007 at 11:09

@Nicodem, "When I needed ethylene glycol I just went to the store, bought the antifreeze with the highest concentration declared on the label and distilled it under aspirator vacuum "

Did you use a fractionating column of any kind for this?

Nicodem - 19-8-2007 at 07:17

No. I only had to get rid of the additives for the use I had for it. A fractionating column would be no improvement. I can't imagine why would I want to use it (not to mention how difficult can be using a column when distilling something with such a high evaporation enthalpy and low vapor pressure like ethylene glycol).

Vacuum distillation of EG

jamit - 16-3-2012 at 13:16

Quote: Originally posted by Nicodem

You can get antifreeze with ethylene glycol content up to 95% (at least where I live). You can not use extraction as a method of purification for ethylene glycol since its partition coefficient is unfavorable for any solvent you might try. When I needed ethylene glycol I just went to the store, bought the antifreeze with the highest concentration declared on the label and distilled it under aspirator vacuum (you need to use magnetic stirring as well else ethylene glycol bumps terribly during vacuum distillation). You can also distill at atmospheric pressure (but use an air cooled condenser) but given the b.p. of ethylene glycol this is not very practical. There are some additives in most if not all antifreeze formulations that remain in the flask so do not distill to dryness or they might start decomposing and contaminate your distillate. These are actually the only reason why you need to distill it.

@nicodem.

When you vacuum distilled ethylene glycol what temp did it come over?
I tried simple distillation and it melted my
keck clips... It's too high a boiling pt so I'm considering vacuum distillation and would appreciate your experience on this. Anyone else who's tried vacuum distillation of high Bp of solvent would be welcomed too.

Magpie - 16-3-2012 at 13:34

Quote: Originally posted by jamit

I tried simple distillation and it melted my
keck clips... It's too high a boiling pt so I'm considering vacuum distillation...

Yes, I melted a Delrin keck clip also. Fortunately I have some ptfe clips so switched to them.

FYI, I used a fractionation column at atmospheric pressure with a ss scrub pad as packing. I insulated the column with a fiberglass blanket. Condensate came over at 196-197C. I recovered about 60mL from 125mL of O'Reilly antifreeze.

entropy51 - 16-3-2012 at 13:53

Quote: Originally posted by jamit

When you vacuum distilled ethylene glycol what temp did it come over?

When I distilled ethylene glycol from antifreeze it came over at 100 - 104 C at aspirator pressure, probably about 10 Torr since it was distilled in winter when the water is cold.

jamit - 16-3-2012 at 18:19

Quote: Originally posted by Magpie

Quote: Originally posted by jamit

I tried simple distillation and it melted my
keck clips... It's too high a boiling pt so I'm considering vacuum distillation...

Thanks magpie for that tip... I considered buying a metal keck clip but it's really expensive about 45.00 for 4 clips.

Thanks entropy for the info on vacuum distillation of EG... So it's between 100-105c. At these temp I don't have to worry about melting my keck clips. Thanks guys!

CaptainPike - 16-9-2013 at 15:08

I'm going to try doing this distillation. My best thermometer only goes to 160°C, but I do have a little vacuum pump I've reconditioned and I'm dying to try out. It's one of those KNF lab jammies, a diaphragm pump. I don't know how much of a vacuum it will maintain pulling on my apparatus. I will calibrate by measuring at what temperature it will boil some water using the same set up.

I think in this area we can buy anti-freeze that you're supposed to mix half-and-half with water, implying it's all ethylene glycol. The stuff is deep green, so there's got to be something weird in it. I'll expect a water for-run, around the temperature of my aforementioned calibration. Then, who knows what I'll get. I'll look for some syrupy clear stuff, possibly doing a density check as was mentioned above.

If anyone has any cautions, advice or just comments I will be interested to read them. Thank you.

PHILOU Zrealone - 17-9-2013 at 01:39

If the distillation of ethylene-glycol is a problem...
Maybe, but it is more work:
-first conversion into 1,2-dichlorethane via Zn dichloride and conc HCl, then distillation of the alkyl dihalide (what should be much more manageable), then hydrolysis with aq NaOH to form NaCl, water and ethylene glycol...finally pass dry air into the media, water will leave the system and NaCl cristallise...leaving concentrated ethylene glycol.
-Aceton in concentrated acidic media do form a cyclic-cetal with ethylene glycol what is easier to distill than EG...
The reverse cetal opening is done in diluted acidic media upon boiling...If you used sulfuric acid, then addition of saturated Ca hydroxyde solution will precipitate hydrated gypsum...here again you have EG and water and a cristallised salt...aceton first leaves the system. Then dry air blowing should get you to concentrated EG.

stoichiometric_steve - 19-9-2013 at 15:15

that's like the worst method ever.

Pulverulescent - 20-9-2013 at 01:45

My method was to ask my local pharmacist, wait a few days, and just pick up my 2½ litres of EG . . .

CaptainPike - 20-9-2013 at 06:51

I think PHILOU's way represents some "out of the box thinking"– maybe even out from under the Christmas tree thinking. Convert the thing to something with a more reasonable boiling point (allbeit a little show-offy)is a solution coming from a brain with a bigger experience set. It's like he is a chemist or something. also got me interested in zinc dichloride, butter of Zinc, a compound having very interesting properties. And isn't there some guy that would say, "1 2-dichloroethane, that's dangerous isn't it?"

Talk about being a brown scientist(as opposed to green), I don't even really need the EG now, I'm just learning about protection mechanisms. I always thought real ethylene glycol was green. I am just a recovering Saab mechanic, used to its taste, smell and white smoke in the exhaust! I can tell you about microcracks in the exhaust port of an aluminum head, but I never knew the curious molecular palindrome that e.g. is.

I think I'll just turn my hotplate up to high, make a little tent out of tinfoil, see if I can't distill a little ethylene glycol! Screw the thermometer, full heat instead! Pretty corny, I know.

bbartlog - 20-9-2013 at 19:59

You'll need the full heat. Maybe even a bit of cloth around the stillhead depending on your setup. Still, it's pretty straightforward once you manage to limit the heat loss to a manageable level.

CaptainPike - 7-1-2014 at 10:22

I have enjoyed learning a lot of stuff about ethylene glycol. This whole process of deciding how to distill a little EG has really revealed a lot. Some questions or ideas I have:
1) What the heck is a boiling solution anyway? When we have an aqueous solution of ethylene glycol, which appears to be boiling, it means that molecules of both substances are in the process of transitioning in and out of the liquid state, right?

2) This temperature (BP above) reveals the relative composition of the still pot. Is this also the relative composition of the vapor? Graphs of this are shown on pages 14 and 15 of http://www.meglobal.biz/media/product_guides/MEGlobal_MEG.pd... This relationship implies that a 50-50 solution will have a reasonable boiling point around 110°C.

3) What happens if we continue boiling our 50-50 mixture, removing and doing something that we want to with the vapor? If we think back to simple distillation (even given an azeotrope) we've got to believe that we are removing more of the lower boiling point liquid. Just like those blue collar chemists in the hills of eastern Tennessee: azeotropes and vapor pressures aside, those guys are collecting a pretty low boiling distillate! But in our case, wouldn't we be increasing the relative content of ethylene glycol in the still pot?

4) It seems that if the above is true, can we add water back into the still pot, and make our job easier? There is a patent registered (3, 398, 061) for an EG recovery system, where the guy does this, I think. Too easy to be true, my skeptical mind says.

I can picture the apparatus. A 1 L three neck RBF (splayed necks) clamped down on my hotplate, having an angled still head fitted on one of the side necks with a thermometer adapter. Then an additional three splayed neck RBF (maybe only 500 mL) with one of its out board necks plugged directly into the still head (no condenser at all). Hopefully, all these splayed necks along with the angle introduced by a typical still head will result in the smaller flask being nearly level. Into the center neck of this receiver we fit another thermometer adapter.
Would it be possible to heat up the big RBF to boiling and collect ethylene glycol in the other flask? I guess it would be a matter of controlling the temperature of that steam coming out. Could that smaller flask be kept hot enough to boil off the water vapor and still collect the ethylene glycol?

I'm going to have to try this out. Any ideas? I know, I know I should be performing a vacuum distillation but this jug I have here is a PEAK ready mix product – they only charge a little bit extra to cut your stuff 50-50 with water, LOL. What I want to know is: can we exploit this fact of the shift in boiling point based on concentration (at constant pressure) to collect and purify EG in a simple way?

I would welcome comments from the you folks. That's another thing great about this online forum business – I can show my ignorance, and hopefully learn something and not worry about being laughed out of town!

Just my two cents

franklyn - 8-1-2014 at 09:13

An original way to dry ethylene glycol would be by electrolysis. Introducing ammonia gas into the mix will form a weak electrolyte with water allowing a current to pass. Ammonia and hydrogen come out at the cathode. The process will be complete when no more oxygen evolves at the anode.

.

Dr.Bob - 8-1-2014 at 13:02

I think people need to be aware that distillations are not quantum events. You will never get all of the water out of EG as a single fraction that boils at 100C exactly. When you have mixtures, that changes BPs due to azetropes and other physical effects (much like adding salts increasing the BP of water), also changes in atmospheric pressure will changes BP by a few degrees, thermometers are not all ideal, many are not immerses to the correct point, etc. So don't expect the BP of EG to be 196-197 for a quick distillation of a 50:50 solution. If the starting material is close to pure already, you insulate the glassware, your thermometer is calibrated, and you distill slowly, you MAY get a 2 degree range, but that would be the most ideal case, most users will not get that narrow a band.

Most distillations are a curve, where the BP starts very low, ramps up to near the lower BP component, and then the temp slowly goes through the lower BP range maybe from 95 to 105C for water, where mostly water boils off, but some other solvents and traces of EG, mostly depending on the quality of the distillation system and the speed of the distillation. Then, when MOST of the water is gone, the temperature will start moving up quickly, this is an ideal time to change receivers, as this will be a mix of both water and EG, once the temp increase slows around 190-195C, then you could start collecting crude EG, and the temp will then very slowly increase, in most cases you will have a several degree range.

If you really want pure EG, the way is to first do a crude distillation and get the material 90+ pure, then do a slow, careful one to get it pure. Since most of the salts and other solvents are now gone, the BPs should be much more accurate now. But you will still have changes in barometer that make it a relative range, not an absolute value, unless you are willing to check the pressure and correct.

Lastly, there are many ways to test the EG, use an antifreeze tester, they should show 100% EG, density (weigh a known volume and compare to tables of density - yes they exist and are not completely linear, much like ethanol water mixtures), or use refractive index, testers are available at many wine/beer brewing stores.

But it should be easy to find nearly pure EG for automotive use somewhere.

Random - 8-1-2014 at 13:04

Franklyn that would be terribly unprofitable.