Sciencemadness Discussion Board - Is there anyway to purify MgSO4 that contains fragrance oils?

Is there anyway to purify MgSO4 that contains fragrance oils?

Velzee - 28-8-2015 at 11:28

Last time I tried to make anhydrous MgSO4 (to use as a desiccant) by heating pot of it on the stove, but an overwhelming smell of the fragrances flooded my apartment and nearly suffocated my family and myself. Is there a way to separate the MgSO4 from the oils? Here are the list of ingredients included in the Espom salt:

Thank you in advance!

Praxichys - 28-8-2015 at 11:46

The easiest way might be to bake the oils out. Mostly MgSO4 is used for drying in the lab and has to be baked first to remove water.

I say bake it to death as high as the oven goes for an hour or so. If the oils cause browning of the product, dissolve it, filter (to trap the carbon particles), evaporate, and re-bake.

You could also try extracting the oils with a solvent but you will lose a lot and it will be messy.

MrHomeScientist - 28-8-2015 at 12:09

If they actually are oils, I'd think dissolving in water and decanting the floating oil would be easiest. Then evaporate to crystallize, and heat in the oven until anhydrous.
Trying to heat to decomposition surely would leave a dirty carbon-contaminated product and produce lots of smells (as you saw). Not that carbon would interfere with drying, of course, but I'd prefer a pure product since it seems like a pretty easy separation to me.

Velzee - 28-8-2015 at 13:01

Quote: Originally posted by MrHomeScientist

If they actually are oils, I'd think dissolving in water and decanting the floating oil would be easiest. Then evaporate to crystallize, and heat in the oven until anhydrous.
Trying to heat to decomposition surely would leave a dirty carbon-contaminated product and produce lots of smells (as you saw). Not that carbon would interfere with drying, of course, but I'd prefer a pure product since it seems like a pretty easy separation to me.

And what if the "oils" don't simply float to the top? I just made a saturated solution a few minutes ago, but I do not see a distinct layer:

Praxichys - 28-8-2015 at 13:11

@MrHomeScientist - I had originally though that too, but there probably won't be enough oil to float. It will end likely up as an emulsion/solution, especially since a lot of those fragrance oils are pretty dense. Carvone and eucalyptol, for instance, are pretty close to 1, and their oxygen content makes them polar enough to dissolve in water just enough to keep everything contaminated. There also exists the problem of the likely air-oxidation that has happened to those oils, likely forming very tiny amounts of gummy crap that clog filters easily.

If you get lucky you might reduce the oils by dissolving and drying a few times, but pyrolysis is the easiest 1-step guarantee. It does no favors to the kitchen, however.

I suppose one could make a saturated solution and extract with a nonpolar solvent many times. Or, perhaps recrystallizing from water and decanting a significant portion of the liquor which would hopefully retain the oils. It's a tricky situation for sure. I'd like to know what works!

EDIT: Dang it, posted at the same time.

[Edited on 28-8-2015 by Praxichys]

DraconicAcid - 28-8-2015 at 13:14

That's too cloudy to be a solution. Let it sit for an hour or so, see if anything floats or settles out.

I'd actually try stirring it with isopropanol. It shouldn't dissolve much MgSO4, but will dissolve the oils.

Velzee - 28-8-2015 at 14:19

Quote: Originally posted by DraconicAcid

That's too cloudy to be a solution. Let it sit for an hour or so, see if anything floats or settles out.

I'd actually try stirring it with isopropanol. It shouldn't dissolve much MgSO4, but will dissolve the oils.

About an hour after adding some isopropanol, the solution remains cloudy, with the exception of a ~1mm thick "dirty" layer with odd particles in it, at the top of the solution. I'm going to allow the solution to stand for about a day or so.

Velzee - 29-8-2015 at 06:56

The solution looks the same after about a day.

Texium - 29-8-2015 at 07:08

If I were you, I would try to find a brand of epsom salts that doesn't contain any fragrances. The kind that I buy is just USP grade magnesium sulfate, with nothing else in it. Much less of a hassle to work with.

DJF90 - 29-8-2015 at 08:56

Draconic acid was probably referring to trituration of the MgSO4 solids with isopropanol.

Amos - 29-8-2015 at 10:25

I'd just dissolve it in boiling water, filter(if you see any particulates) and then slowly cool the solution, first at room temperature and then in a freezer to crystallize it. Your crystals should be pretty much pure magnesium sulfate. Then take your leftover solution, heat it to boiling, add more magnesium sulfate, repeat.

[Edited on 8-29-2015 by Amos]

Velzee - 28-10-2015 at 12:16

Quote: Originally posted by DraconicAcid

I don't think the oils dissolved. Perhaps something else could solve my problem?

zed - 28-10-2015 at 13:47

Me, I'd just roll down to the local "Dollar Tree", and buy some unscented product.

Cheap and simple.

Ozone - 28-10-2015 at 15:51

I think what was meant was to stir with the alcohol, and filter the liquor off. Repeat until the solids are free of fragrance.

A soxhlet would work well, here.

O3

[Edited on 28-10-2015 by Ozone]