I tried extraction with dichloromethane using the Stb method, but it emulsified. I'm currently adding rock salt and checking on it, but it doesn't seem to separate. From now on, I'm going to warm it up with warm water. Is there a way to make separation easier when using dichloromethane?
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Stb method, dichloromethane, emulsification
- Thread starter sunset35
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DCM really shines in A/B extractions.. particularly if using a sep funnel. High pulling power, extremely non-selective, faster evapping than any of the other commonly used solvents.. its brilliant. But is important to note that it can be prone to emulsifications. This is especially the case if there is a large amount of precipitate in the mixture, because they will compete for the bottom of the vessel. It may actually be less emulsified than you think.. but gravity/shape of vessel can make it look worse than it is. Add large amounts of bark sludge into the equation and you might be in for a bit of a nightmare. Put on some gloves and goggles and strain it all through a pillowcase or something.. the liquid without the bark sludge will have a better chance of separating (gross, I know..) . Either that, or dilute the absolute sh*te out of it.
If doing STB, I'd at least make sure your vessel is flat at the bottom... if its cone shaped then precipitate/bark sludge will compete for the real estate
Curious, in a flat bottomed vessel does it start separating?
Good luck, and god bless DCM
If doing STB, I'd at least make sure your vessel is flat at the bottom... if its cone shaped then precipitate/bark sludge will compete for the real estate
Curious, in a flat bottomed vessel does it start separating?
Good luck, and god bless DCM
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DCM has a density of 1.3266 g.cm-3, so adding a lot of salt may actually hinder separation as saturated brine starts pushing the 1.2 g.cm-3 level.
www.engineeringtoolbox.com
if you start warming it, it'll evaporate very quickly, with a boiling point just below 40°C and a vapour pressure of 57.3 kPa already at 25°C.
Sodium Chloride Water Solutions
Freezing point, density, specific heat and dynamic viscosity of Sodium Chloride and Water coolant.
www.engineeringtoolbox.com
if you start warming it, it'll evaporate very quickly, with a boiling point just below 40°C and a vapour pressure of 57.3 kPa already at 25°C.
DCM has a density of 1.3266 g.cm-3, so adding a lot of salt may actually hinder separation as saturated brine starts pushing the 1.2 g.cm-3 level.
Sodium Chloride Water Solutions
Freezing point, density, specific heat and dynamic viscosity of Sodium Chloride and Water coolant.
if you start warming it, it'll evaporate very quickly, with a boiling point just below 40°C and a vapour pressure of 57.3 kPa already at 25°C.
The plant pieces were separated using a muslin cloth.
However, having added a lot of rock salt, the emulsion does not dissolve. Is there any solution? Do I have to throw it away?
Are you using a separatory funnel?
As acacian mentioned, you ought to see if there's anything that will drain off underneath. Otherwise, dilution with pure water may be necessary to reduce the density of the aqueous phase as also previously mentioned.
You may be able to break the emulsion by using a vibrating massage device/sex toy. Fixing it firmly to the outside of the vessel should suffice. With luck, the DCM should settle to the bottom within about an hour.
Failing all of that, you may be able to pull out the DCM with the use of light naphtha. Yet another - least favorable - option is to let all the DCM evaporate and start again.
I do hope you haven't been expecting the DCM to float to the top, btw.
