Removing Glycol from a water mix

Hello pipefitter3524,

You don't state whether your mixture is ethylene glycol, propylene glycol, diethylene glycol or other glycol.

Check the properties of the particular glycol you have in your mixture, by Googling for table of properties of your specific glycol.

Easiest way, if you need to separate by the boiling method, is to have your mixture in a closed container, preferably with a vacuum pump suction applied, and have your thermostat keeping the mixture heated so you maintain the boil off temperature of the lower boiling point of the two mixed liquids.

The lower boiling point liquid will then steadily boil out of the mixture, the faster moving molecules first, and be sucked by the vacuum pump, through a large condensing chamber, which is cooled, perhaps by chilled water, or other method.

There is also a different and easier way: Freeze your mixture, and the different component liquids will normally separate, and one may be easily removed from the other, once one has frozen.

Please reply with.....

I'm new to this forum so I was trying to provide simple request. I also did not have the advantage of spell checker or I would have specified the types.

I'm working with ethylene glycol and propylene glycol removed from large systems for a myraid of reasons. I want to responsibly recycle this fuild first by filtering then by concentrating the mix back to pure glycol of the type. I like the boiling version and was thinking I'd need an atomsphere in the vessle or as you suggested vacuum which would have the added benifit of reducing the boiling temperature. At this time I'm going to build a pilot operation and see how it works. Thank you for your input this is an awesome website.

Depending on quantity and purity required 100% (?) a fractionating column might be applicable.

I do not understand this term, can you point me to a research source?

Thank you for the input.

A fractionating column is a vertical column of chambers. You glycol mix would be piped in near the top of the column, the bottom is heated and the water vapor goes up and the glycol trickles down. More details at Fractionating Column

I receive large quantities of fluid removed from ice building systems.

Ice making systems? What kind of glycol?

Thank you for the information, I printed it and breifly viewed the information, basically a still?

From a chemical engineering standpoint, a fractionating column would likely be the best option for such a separation. Perhaps the poster has access to someone that runs a tolling operation for handling such a purification scheme; there are some around. Unless he is going to be doing a lot of this type of separation, the cost would likely be prohibitive.

Are you talking about ethylene glycol in an automotive application? What are you trying to accomplish? If only to concentrate the glycol and then dilute it again, the commercial processors in my neck of the woods just filter it, determine the dilution %, check and adjust the additive package, add more glycol to adjust the dilution to 50% and sell it as 'ready to use, no dilution necessary'.

I receive large quantities of fluid removed from ice building systems. to reuse it in a commercial application I'll need some manner of process certification.

Thank you for your input.

If you Google "distillation of ethylene glycol" you will see a bunch of information.

Tad

Wow, a lot of information, Thank you

Hello again pipefitter3524,and thank you for your prompt feedback.

If you use the boil and condense system in my earlier Post, set your thermostat/heating for the mixture to the lowest glycol boiling point first, and that will boil off and be condensed first.

You then are able to remove that liquid, and proceed further..

Then set the thermostat for your heater to the next boiling point, and so on.

This may be repeated for a number of miscible liquids.

I do agree that a fractionating column is far superior,and does the job so much faster.

It depends on the quantities you have arriving, and costs - as the fractionating column has to be carefully designed, certified, and is expensive to start up and run.

Advise of your progress, please.....

You are going to need a method of QA/QCing the production quality from the process also. A fractionating column is the best bet and not that complicated, it is the proper calibration that is complicated. The simple description of one is what is typically used in chemistry labs. It is a still with many refactory surfaces in the vertical column above the still boiler, for labs this is typically something like glass beads or glass wool packing. there are plastic structures for this in fractionating columns.

Thank you for the explanation

maybe a little off topic, but I have always been told to change anti boil/anti freeze in car radiators every 12 months, as the 50/50 mix of di-ethylene glycol becomes corrosive as the glycol turns to ammonia- anyone who uses the above mix knows how expensive glycol is- (I personally use tannin & rain water with pH adj to 9-10- & change every 2 years or sooner- from experience with water treatment of steam boilers)- I can say that I have never had corrosion or blockage of the engine or radiator. I set up a test- 5 beakers-#1 rain water-#2 cheap coolant as bought from supermarket- #3- rain water & tannin/alk mix as I use- #4 rain water & a tablet(flo kleen)-#5 rain water/diethylene mix 50/50. In every beaker was placed an iron nail & an aluminium strip. Weeks later, the #1 is the only one that shows extensive corrossion of the alloy & the nail- given this is alimited test as the samples have not been heated.

Thank you for the input, this much I can tell you, in heating systems and solar systems using EG I've experienced extensive corrosion. I've not observed this in cooling only systems. The only treatment used on a close loop is usually an inhibitor.

I'm not dealing with the automotive aspect of this fluid but the there has to be huge potential for recycling in both antifreeze and motor oil.

I agree with your saying the fluid is very expensive. We see it purchased by the tanker load.

This is an old post, but you can use a wiped film evaporator, then determine your ‘cut’ for separations.

Before doing anything further with the heating of the mixture thought, check the tables for the mixture you want to separate. Many mixtures have what is called a "Eutectic Point". This is a ratio of the components in the mixture where the maximum concentration has been and no additional heat/distillation will ever increase the concentration further.

Perfect example of this is Ethanol and Water. Heating the mixture will drive off the water until the distillate reaches a maximum concentration of 95% Ethanol and 5% Water. No matter how much you continue to heat the mixture you can not thermally get a distillate greater than this. This resultant 95% mixture is often called "Cologne Spirits".

Any increasing of the Ethanol concentration beyond 95% must be done by other means such as a desiccant, etc.

To test this take some 80 -> 100 proof (40 -> 50%) Vodka which is a mixture of Etanol and water and distill it. The distillate will start as Ethanol, Ethanol/Water (Cologne Spirits) and water after all the 95% alcohol has been heated off.

Keep Cologne Spirits away from college Chemistry lab students. It is very attractive to them.

Good Luck, Old Salt