So I'm carrying out the distillation of some essential oil and I have to remove the water content in it. The usual method is using diethyl ether but I'm looking for a greener method.

What can I do?

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    $\begingroup$ An easy way to remove water from distilled essential oils would be to add some anhydrous hygroscopic salt such as $\ce{MgSO_4}$ to the distillate. I'm not sure what production scale you're talking about, though. $\endgroup$ – Nicolau Saker Neto May 4 '13 at 13:15
  • $\begingroup$ @Nicolau Saker Neto, My production scale is quite small. I'll be producing no more than a few millilitres of the oil. Ah, I initially thought about that. What is the procedure ? Is it as simple as chucking in some anhydrous CuSO4 for example and leaving it overnight ? $\endgroup$ – Ari Ben Canaan May 4 '13 at 16:24
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    $\begingroup$ I don't know if $\ce{CuSO_4}$ is an acceptable substitute. For one, there's a slight chance that the transition metal ion may catalyse the decomposition of substances in the oil. When I distilled essential oils, I'd add a little bit of $\ce{MgSO_4}$ to the vial with the distillate, swirl it around for a minute, then observe if the $\ce{MgSO_4}$ was very wet. If it got all clumped up, I'd add a little more $\ce{MgSO_4}$ until I could clearly see fine particles still suspended when shaken. To recover the oil just use a pipette with a small amount of cotton on the tip to filter out the solid. $\endgroup$ – Nicolau Saker Neto May 4 '13 at 16:44
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    $\begingroup$ @NicolauSakerNeto, some combination of your comments should be an answer. $\endgroup$ – Colin McFaul May 5 '13 at 16:46
  • $\begingroup$ Perhaps this (tiny) article on Erowid (Rhodium) is interesting too for you. $\endgroup$ – Jori May 14 '14 at 10:32

I would suggest adding anhydrous $\ce{MgSO4}$ to your distillate, like Nicolau Saker Neto already mentioned in his comments. Mix the suspension thoroughly (e.g. by stirring) and look how long the salt remains dispersed. When it clumps up and settles quickly due to the formation of hydrates, there is still some water in your mixture, and you need to repeat the procedure until the added $\ce{MgSO4}$ remains dispersed as fine particles for a longer time (it should look similar to a snow storm). After the salt has settled, you can recover the dried oil with a pipette. Because magnesium sulfate is not listed as toxic or environmentally hazardous, it can be considered a "greener" alternative to, for example, copper(II) sulfate or diethyl ether (the latter is additionally highly flammable).

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