I have a steady flow of orange/lime and lemon peels at my disposal, so I have been researching ways to extract the Limonene.
The first and most obvious was steam distillation. After some searching, I found this YouTube video explaining the use of Liquid CO2 to extract limonene straight from orange peels, which is much more economical and seems to produce better results.
So it seems pretty simple, but the scale is small, and I am not sure what the tube is made of. If it is made of glass, it seems the tube would break instead of deforming as a result of the pressure and subsequently letting the CO2 out of the tube.
If anyone has ideas on how this could be achieved on a larger scale, would love to hear it, this also seems like a great way to purify limonene which you have already used - allowing you to re-use limonene over and over again.
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