Extraction of ephedrine from Ephedra Sinica Stapf leach liquor by three organic solvents was studied in an experimental column of 100 mm. diameter packed with 19 mm stoneware Raschig rings. When toluene was used as the dispersed phase

the mass transfer coefficient Koca obtained at 40° was much greater than that at 20°

whereas the difference between Koca obtained at 60° and at 40° was much less pronounced. The values of Koca can be correlated by the following expressions: at 40? --- = 9? + 3.0xlO-2 Koea Vc Vd at 60? --!- = -^j- + 2.0x10-3 K0ca Vc Vd When mixed xylenes were used

the mass transfer coefficient was somewhat smaller than that for toluene

e.g.

at Vc ? Vd ?< 15 m3/(m2) (hr)

K0ca for toluene was 5% higher than that for xylenes. The maximum throughputs were nearly the same in both cases. Although chlorobenzene has a distribution coefficient almost as high as mixed xylenes and much higher than toluene

it is far inferior to the latter two due to very small mags transfer coefficient

very low throughput andliability of forming permanent emulsion with the crude leach liquor. The application of pulsation in the present case resulted only limited improvement in mass transfer process. With amplitudes of 5 ~ 7 mm. and frequencies of 240 ~ 370 cycles/min.

the reduction of (H.T.U.)OC was about 20~35%. The leach liquor with 0.5% of suspended solid matter could be successfully treated in the packed column without any trouble under prolonged or intermittent extractions. According to Pratt[2] packed column cannot handle any liquid containing more than 0.1% of solid

this view may be worth reconsidering if the solid is highly dispersed and does not settle readily. The data of re-extraction of alkaloids from organic solvents by hydrochloric acid were treated according to Sherwoods method[12] for gas absorption with rapid second- order irreversible chemical reaction

and so far as there was some appreciable free acid present in the aqueous phase the mass transfer coefficient was independent of the acid concentration. The following correlations were obtained: (1) Packed column with acid as continuous phase and toluene dispersed

(2) Spray column with acid as continuous phase and toluene dispersed

(3) Spray column with acid as continuous phase and mixed xylenes dispersed

Vw = 2.27 m3/(m2) (hr)

A new flow diagram for the extraction plant was proposed.