MAY, 1953
A CONTINUOUS LIQUID-LIQUID EXTRACTOR FOR ORGANIC SOLVENTS DENSER THAN WATER ROBERT E. HARMAU University of California, Berkeley, California
EXTJXACTION of aqueous solutions with denser organic solvents has been accomplished conveniently, with good temperature control, using the simple apparatus shown. he extraction chamber A, and the outer wall of the coil condenser, were constructed from 45-mm. 0.d. Pyrex tubing; t o permit temperature control, the condenser coil extended into the aqueous solution to a point about even with the uppermost level of the solvent return line B. The length of chamber A and the height of the top of the return line B are critical; the dimensions given in the diagram have been found satisfactory for methylene chloride extraction of dilute aqueous solutions up to about 350 ml. in volume. To carry out an extraction, about 100 ml. of the organic solvent is placed in chamber A, and then the aqueous solution is introduced. The condenser unit is placed in position, and the organic solvent in flask C boiled vigorously. Drops of organic liquid up t o 1 cm. in diameter begin to descend through the aqueous solution. If small volumes of solution are to be extracted, the required liquid level in chamber A may be maintained, with a reasonable volume of organic solvent, by introducing 30-cm. lengths of glass rod. The efficiency of the apparatus was determined by extraction of 1 N acetic acid with methylene chloride and titration of aliquots of the two phases in chamber A . Acetic acid in the organic phase was found to attain 76 per cent of its equilibrium concentration as determined with use of a separatory funnel. This rate of extraction is comparable with that secured in the more complicated and less versatile apparatus used by Hershberg and Wolfe.' In practical use, it has been found that the apparatus will handle systems which give very troublesome emulsions when extraction is attempted with a separatory funnel, or with ether in the usual continuous-type apparatus. A length of wire with a loop a t its lower end, inserted through the top of the condenser and manipulated a t the interface in chamber A, is useful in controlling emulsions. J. B i d Chem., 141, 215 (1941).
20 cm.
A continuous Liquid-~iquidWractor
