VOL. 6, NO. 12
S I ~ LEXTRACTORS E POR CONTINUOUS EXTRACTION
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SOME SIMPLE EXTRACTORS FOR THE CONTINUOUS EXTRACTION OF SMALL QUANTITIES OF FLUID ROBERT M. HILLAND PAULJ. FRYAR, UNIVERSITY OF COLORADO SCHOOL OF MBDICINB. DENVER, COLORADO
During the past several years we have had occasion, in this laboratory, to carry out many extractions of small quantities of aqueous solutions with various solvents. We have used extractors of simple design made in our own laboratories from common stock materials. Their manufacture requires only a minimum of experience in glass blowing. We make no claim for originality of principle in any of these extractors, but because of the interest in them shown by visiting chemists we thought it worthwhile to make this report. We use four different types of extractors, the choice in each case depending on the specific gravity of the extraction fluid, its boiling point, and on thc tcmucrature a t which i t is desired to carry out the extraction. EXtractor Number 1, shown in Figure 1, is for extraction fluids lighter than the solution extracted and of a higher boiling point, e. E., n-butyl alcohol with water solutions. In the diagram, H is a condenser. E is a piece of small-bore glass tubing with a funnel blown on the end. G is the distilling flask for the extracting fluid. The extraction tube D is an ordinary test tube 30 cm. in length into which has been sealed a side arm. This side arm has a slope of about 5 degrees and is attached about 9 cm. from the top of the tube. The distance iV in the diagram should be about 20 cm. The following points in the construction of the side arm are important: (1) The
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bore must be at least 7 mm. (2) The opening a t A must be no smaller than the bare of the side arm and should flare. (3) A hole should be blown a t B about 3 mm. in diameter. The edges should be worked down so that they will not interfere with slipping the cork J into place. (4) The end of the side arm should be beveled a t C in order that the extraction fluid may drip from the point of the tube without obstructing the opening. If the apparatus fails in any of these points the side arm may become stopped by the return flow of extraction fluid. Extractor Number 2, Figure 2, is for extraction fluids heavier than the solution extracted and of a higher boiling point, e. g., brom-benzene with water solutions. No funnel tube is used in this extractor. The condensed extraction fluid merely drips through the solution in D and collects a t the bottom of the tube. By hydrostatic pressure i t is forced back to the distilling flask G through the tube M. The side arm F shonld be fastened about 3 cm. from the top of the tube D. The slope to the point of junction of F and M should be such that the distance 0 is about 8 cm. when the extraction tube D is 30 cm. long. The hole 13 and the bevel C should be thessame as in extractor Number 1. Extractor Number 3, Figure 3, i s for extraction liquids heavier than the solution extracted and of a lower boiling point, e. g., chloroformwith water solutions. In this case the distilling flask U is an ordinary Kjeldahl flask of 500 cc. capacity. The extraction tube P is a test
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work with bent tube upward this tube a small toshould lieglass closely rise tube '/s against sealed of theits to length side. the bottom of For themost test and
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tube but this may be varied according to the specific gravity of the extraction fluid used. A loop T made of , , ...... glass rod 2 mm. in diameter is sealed to the bottom of condenser tube. A similar loop W is sealed to the i: :: ....... the top of the tube P. An S-shaped hook R made of the same rodding serves to support the extraction tube by means of these two loops. The condensed extraction fluid !/ drips through the solution in P, collects a t the bottom ........ .:I. and is forced out through the top of the tube Y by hyj; ;I drostatic pressure. Extractor Number 4, Figure 4, is for extraction liquids FIGURE 4
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VOL.6, No. 12 SIMPLEEXTRACTORS POR CONTINUOUS EXTRACTION
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lighter than the solution and of a lower boiling point, e. g., ether with water solutions. In this type of extractor no advantage is gained from hanging the extraction tube in the flask. Since the solution has a higher boiling point than the extraction fluid the contents of the tube will not boil. The extraction tube T is an ordinary test tube which carries a funnel tube P like the one used in extractor Number 1. The distilling flask is a 500-cc. Kjeldahl flask. The extraction fluid after rising through the solution collects in a layer a t the top of the tube T and simply runs over into the flask below. The temperature of extraction in using extractors Numbers 3 and 4 is of course approximately the boiling point of the extraction fluid. If i t is desired to extract a t any lower temperature, extractor Number 1 may be used in place of Number 4 and extractor Number 2 in place of Number 3 with the extraction tube in a controlled water-bath. These extractors are, however, less efficient than Numbers 3 and 4 due to condensation in the side arms.
