(Moderator)
05-29-03 03:06
No 436200
(Rated as: excellent)
This should prove quite useful for extracting certain types of natural products which are prone to form emulsions, courtesy of the USDA, from JACS 35 295-7 (1913)
The method of shaking out with immiscible solvents is sometimes tedious or quite impracticable on account of a tendency to form persistent emulsions, even on cautious agitation. This is especially true of the separation of organic acids, bases, etc., from animal and plant extracts, which often contain mucilaginous or albuminous constituents. A consideration of the theory of the distribution of substances between two immiscible solvents in contact with each other led to the devising of a new form of separator to overcome this difficulty. Assuming that the rate of transfer of the dissolved substance depends upon, the difference between the condition of equilibrium and the existing ratio of distribution, and also upon the area of the surfaces in contact, the transfer will be promoted by the continual presentation of fresh portions of the respective liquids into contact with each other and also by an increase of the contiguous surface. This is usually effected by shaking the two liquids together, but when shaking causes emulsification other expedients must be resorted to. Thus separators of fiat form were made, which during the extraction process are used in a nearly horizontal position, but are placed erect when the contents are to be drawn off. These separators are made in two sizes, namely, 12.5 and 17.5 cm. in diameter, and in use the liquids are spread out in thin layers so that the contiguous surfaces are 8-10 times as large as with the same amounts of liquid in separators of the usual form. To produce a gentle movement of the liquids upon each other an apparatus is useful. This consists of a nearly horizontal rotating (20 revolutions per minute) disk A which is slowly turned through a worm gear by means of an electromotor. The inclination of the whole apparatus may be adjusted by a hand-screw, B, in the base. The separators lying on the rotating disk are gently tilted about so that no mixing of the two liquids takes place. To support the separator vertically while drawing off the contents, two right-angle screw hooks are inserted horizontally in the edge of the laboratory desk shelving with a space between them somewhat less than the diameter of the separator. The apparatus has proven satisfactory in practice.
Chemistry is our Covalent Bond
(Hive Addict)
05-29-03 05:32
No 436225
Yeap,
I noticed emulsions took alot longer to settle out in a small seperatory funnel, than a large beaker with a large surface area.
Neat piece of glassware.
(Hive Addict)
05-29-03 20:40
No 436381
I have often set up my sep funnels horizontally to resolve emulsions faster ( keck clip on top stopper!). This looks really cool.. i'll see what my glassblower will charge for one..
Infinite Radiant Light - THKRA
(Title Addict/Eraser)
05-29-03 22:29
No 436406
jetson has noticed that if one takes their sep funnel tilted on its side and spins it it speeds up the seperation of emultions also.
the devil is so lonely
