Hey so Swim has a few liters of used yellow d-limonene that he would like to re-use. Many posts say the best way to clean it is through distillation, however they dont really go into details about the distillation of d-limonene.

Obviously heat, condense, and collect... but d-limo boils at 176 degrees C. Thats a really f'ing hot distillation! Are there any people that have done this? Is d-limo pretty safe to heat that high using a standard lab distillation set and a hot plate?

A main question I have is that since literature states you can steam distill d-limo from orange peels at 97 degrees C, is it possible to add a volume of water to your d-limo, and with mag stirring, distill over your d-limo + water at a much lower temp like 100 degrees C instead of 175 degrees C?

too large a volume of d-limo, the water/oil bilayer would most certainly bump.
the way to distill it is under reduced pressure (using a distillation apparatus with a vacuum take-off adapter)

Is it absolutely necessary to use a vacuum still? Or can you safely heat it to 175 C with no problems?

A lab vacuum pump is still on the shopping list unfortunately so its not really an option..

I've distilled my d-limo upwards of 5 times using an Electromantle heating mantle and a Liebig condenser...no difficulties have been encountered to date.

Very nice, thanks snozz.

is it possible my year old dlimo dosent pull fb molecules like it did, it seem to becoming less effective

Ya thats why Swim wants to distill it, I hear yeilds go way down after its been used.

Just thought I would update this. D-limo distillation of 2L was successful.

Set up distilling set and set to mag stir with 9/10 heat on the hotplate. Heated up in about 20 minutes and took about 4 hrs to distill the 1.9L, giving clear d-limo ready for use. Left about 100ml of brownish-yellow green used d-limo that was discarded. Swim was alittle nervous at first about heating something way up to 170 C for distillation, but there were no issues and it seemed plenty safe.

On various websites shelf life of D-limonene is listed at a range of 8 months to 2 years.

I have a container with about 2.5 gallon of 3 year old used yellowish d-limonene. Would it be possible to distill part of this to a pure product again or is this not possible because of degradation of the solvent that already occurred?

Was the d-limonene you guys used already past the supposed shelf life?

Could a moonshine stiller work for recycling the limo? Benzyme warns about bumping; is this a problem when you distill let's say 1 gallon of d-limo with 1 gallon of water added in a 5 gallon reservoir?

They are large volume and far more cheaper than let's say a 2000ml glass setup. With the price of D-limonene it could be a good investment to recycle it if one is extracting on a regular basis. As a bonus I could distill my lavender plants and other herbs/flowers on the property and grow a beard and make some moonshine in the woods.

They can be bought for about 200 $ for 5 gallon volume on eBay. Something like this:

Your pic makes me feel nice inside!

I think it would still bump if used with water though.

Be careful if distilling gallons of flammable solvent at 176'C!

Something possibly to try with limonene is washes with aqueous sodium carbonate and IPA. Pulls quite a lot of yellow/brown gunk from the limo, but needs a water wash or two to get rid of the alcohol after that. Possible interesting gunk in the IPA layer.

Thanks for your reply, much appreciated.

I was hoping that the 3 gallon overhead could make up for potential bumping (leaving more space for the bumps). The idea was to use the water to keep the boiling point at 100C instead of pure limo at 176C actually the same way as orange peels are distilled.

What would happen if you still pure limo at 176C in a pot still? The vapors stay as flammable as the vapors at 100C, are there other dangerous factors when raising the temperature as opposed to steam distilling?

On another forum I got feedback as well, that this example of a moonshine wouldn't work for steam distilling the solvent because of the reflux colon which means should look out for a simpler model pot still i guess.


I looked into the bumping problem some more and found this document:

http://web.mit.edu/5.310/www/Essential_oils.pdf

It is stated that performing vacume distillation the bumping could even get worse (though boiling point lowers), which speaks against an earlier post in this topic.

"Two problems are encountered in a vacuum distillation. The volume of vapor formed from a given amount of liquid is pressure dependent; i.e., the volume of vapor formed from one drop of liquid will be about 30 times as great at 25 torr as it was at 760 torr. As a result, serious bumping may occur. Boiling chips generally do not help much at the reduced pressures. Some of the bumping can be overcome with the use of a magnetic stir bar. The second problem is also related to the larger volume of vapor at lower pressure. The velocity of the vapor entering the column is greatly increased. This creates a greater pressure in the column than is registered on the manometer. Maintaining a slow, steady rate of distillation can minimize this difference in pressure."

So finally I recycled the old d-limonene.

I bought a hotplate with stirring functionality. I added to a 3000 ml round bottom flask about 1000 ml water and 500 ml of used d-limonene and started stirring and heating. Somewhat under 100 C the solution began to boil and the water and d-limonene came over in a ratio of about 60 % water and 40% d-limonene. Quite strange too me as water boils at 100 C and d-limo at 175 C the mixture started too boil below 100 C.

The boiling went very smooth. I switched off stirring for a moment and it boiled a bit more aggressive because of that, but still it would work fine without if you keep the d-limonene layer small compared to the water volume so the water can easily come through the layer and mix at the top.

The only downside.... it takes really a long time. I think that 500ml d-limonene took about 8-10 hours to distill.

Most probably distilling the pure d-limonene goes a bit faster, but I didn't want to heat up to 175 celsius as the auto ignition point of d-limonene is around 255 celsius and it seems quite close to the boiling point as opposed to for instance acetone which boils at 57 C and auto ignites around 465 C

Can someone maybe explain how the d-limonene could reach a higher temperature than 175 while distilling without adding pressure or superheat the solution somehow, so that it can reach it's auto ignition point?

If that possibility is rather low or virtually non-existent I would distill it at 175 C without adding water next time to reduce time a bit.

You might study what this guy is doing to distill limonene for cannabis extracts. It's been a while since I watched the video (don't remember details) but he seems to have good success.

https://www.youtube.com/watch?v=TPQhamiRH-Y

Sum of partial vapour pressures means the boiling point is below 100 C for water plus another component.

Looking further back, note that limonene slowly oxidises to carvone and other similar compounds especially when wet; starts to smell a bit of caraway/mint after a while.

Thanks for the explanation.

I read about the degrading into carvone, but since the boiling point of carvone is 231 C it shouldn't came over in the distillation. I kept watching temperature and didn't fully distill the limo off. Also probably carvone has similar properties as d-limonene in extracting alkaloids. It's used in the food industry as well for flavoring so it is not worrying me to much.
I have somewhere a paper on my drive which states the degrading of the oil is most likely greatly exaggerated. Also I don't smell any mint in the distilled oil, the residual dark orange oil layer might have a hint of it.

One problem with carvone is its reactivity, being a ketone it can be slightly more inclined to forming intractable crud. Also, it's more polar and I have a feeling this can screw up phase separations a little bit.

I think as well the rate of degradation is pH dependent and can be catalysed by tertiary amines via their oxides. (Just a hunch, and I'm not saying it happens very quickly.)

Residual dark orange layer sounds like the stuff. Did you ever examine it or has it gone 'in the garbage'?

I kept the residual orange oil and also I kept the aqueous residue which actually contains some solubles from the limonene as it's now cloudy and yellowish.

I found a reference document for TLC and reagent analysis for essential oil. I'll order some vanillin and do some agent testing on the residual water and oil as well as the distilled product when I find some time.

D-limonene should react with sulphuric acid and vanillin showing a deep pink colour whereas Carvone should show as faint violet.

Unfortunately the solvent used in table 1 is Benzene:methanol and I don't want to work with benzene for obvious reasons. It would be great though as d-limonene as well as carvone is referenced.

In table 3 n-Hexane:Ether (which are both easily obtainable here) only carvone has an rF value and d-limonene was not included.

MERGED

Hello,

Since I couldn't post in the below thread, I link it below:
recycling limonene-D through redistillation.

I had 2.5l of used d-limonene stashed in glass vials for roughly a year. It was used for a san-pedro extraction.
Finally got around to redistilling it to get rid of the yellowish tint.
Used a mag-stirring heating mantle. It's, of course, imperative to use silicon sealing grease.
Attached are a few photos of my setup.
Tried to stay below 200°c (limonene temperature) at all times to avoid any risk of spontaneous ignition.
I didn't add any water bust still got some at the beginning in the decanting flask and just got rid of it.
The whole process took about 3 hours. The rate was very fast drops bordering on trickle.
Thanks to all for the useful infos (mainly boiling and spontaneous ignition temperatures). Hope this helps.

Just saw your addition to this thread; nice trufo.

I realized why my distillation took so long.

I used a vertical setup with a 30 cm dimroth condensor (usually used for refluxing). In between the condensor and the RBF I installed a globular splash glass with an outlet to output the distillate.

Later I realized that the globular splash glass reached quite high of a temperature as well so the drops coming back from the dimroth partially got evaporated again in the splash glass and went up again.

I ordered a Liebig condensor and will try again without the splash glass. It should go a lot faster faster then. I'll still add the water because it feels a bit safer to me.

A bit off topic:

I recently added some anhydrous magnesium sulfate (baked in oven for two hours) to some d-limonene to see if any water was absorbed. Strangely the magnesium sulfate kind of got dissolved forming a second small slurry layer. Still I don't get this as the d-limonene clearly formed two layers when water was added indicating that it's non-polar properties were still the same.
This implies that although the d-limonene was formed nice seperation with water it still contained water by itself, or the magnesium sulfate I bought was not actually magnesium sulfate??

Actually I had the same happening with adding the magnesium sulfate to acetone. It almost got fully dissolved. This might have had something to do with high water content of the acetone. Still I was under the assumption that it couldn't get dissolved in water, just absorbing it.