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Author: Subject: Extracting Coffee Oil for Candles
Meltonium
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[*] posted on 31-12-2017 at 10:03
Extracting Coffee Oil for Candles


Hello,

A few years ago, I purchased some n-hexane to extract oil from coffee grinds. At the time I didn't have a soxlet extractor, so I used a pressure equalizing addition funnel in its place. After removing the hexane, I was left with the coffee oil. It was a dark brown, viscous liquid that had no solids present.

A few months ago, I extracted more oil from coffee grinds, but this time I used isopropyl alcohol in place of hexane. After removing the isopropanol, I was left with a brown, viscous liquid with some fluffy brown solids present.

These oils were used to make coffee scented candles in beakers. The candles made from the first batch of oil were light brown in color and sweet smelling. When the oil was added to the melted soy wax, it dissolved almost immediately and turned the molten wax a deep brown color.
When oil from the second extraction was added to a different pot of molten wax, the oily part dispersed but the solids remained until the mixture was stirred. The solids broke apart and seemed to dissolve.

Candles from both batches were nearly identical.

Here's the kicker: I have been extracting more coffee oil more recently using ethanol (well, it's a mix of ethanol with a bit of ethyl acetate). The coffee oil I got from this extraction was dark brown-black in color and did not have any solids present. However, when I added this oil to the wax, It immediately sank to the bottom. Upon stirring, the oil broke apart and seemed to dissipate, but there soon was small black bits of something in the wax. It looked as if the oil had burned. In addition, the candles made from this mixture turned black at the bottom (did the oil separate out or something?) and in multiple instances, small bubbles that formed around the rim of the candle solidified and turned into the black bits seen before.

In all three instances of candle making, no procedure was changed. The only this that changed was the method of extraction used to get the oil.

Is the oil burning? Or is there something in the oil that is decomposing into the black bits? Why was there no decomposition when I used hexane?




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SWIM
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[*] posted on 31-12-2017 at 10:17


I suspect its a question of what you're extracting in each instance.

hexane, isopropanol, ethanol.

That's a succession of increasingly more polar solvents which will extract a different range of substances from the grounds, and these extracts, although overlapping in many constituents, will have differing ingredients and properties.

Solvent residue in the extracts may also make your extracts more or less soluble in the wax.
Hexane dissolves most waxes well (and therefore dissolves in them well), but ethanol not so much.
If the extract prefers the ethanol to the wax you'll get something like what you're describing.




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Meltonium
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[*] posted on 31-12-2017 at 10:32


Thanks. So I guess I should be extracting with a more non-polar solvent to get the results I desire. Unfortunately, I am out of hexane. Do you think ketones could work? I know that they are polar, but I'm thinking that MEK might work well. Though, I am concerned that the MEK could polymerize when extracting the oil, since I don't know what's in it.



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[*] posted on 31-12-2017 at 14:58


Use lighter fuel for Zippos.



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[*] posted on 31-12-2017 at 15:36


Petroleum ether would work ok. You might try distilling gasoline to obtain a suitable solvent, but it could be tricky to get a fully saturated one that way.



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[*] posted on 31-12-2017 at 22:00


Any hydrocarbon solvent will work fine in your case: petroleum ether, VM&P naphtha, Shellite, Coleman fuel, white gas, any alkane, toluene, xylene, hydrotreated light distillate, etc.

I would caution against using distilled gasoline, as I have gotten some weird results. I recently distilled a few liters of gasoline, collecting the fraction which boiled between 45-90 degrees Celsius. After washing the fraction with concentrated sulfuric acid, the bulk of the mixture now boiled at over 150-200 degrees. WTH?
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