Multistage countercurrent extraction

Countercurrent multistage extraction is the application of SFE to the fractionation of liquid mixtures and the purification of liquid substances. SFE in the modification of countercurrent multistage operation extends the possibilities of separation processes, such as fractional distillation, absorption and liquid-liquid extraction to the isolation and purification of components of low volatility. The separation of volatile liquid components is also possible at tempera- 

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A countercurrent multistage extraction system is shown below, which is to be modelled as a cascade of equilibrium stages. 

Related Calculations. This basic calculation procedure can be extended to the case of countercurrent multistage extraction with reflux. A schematic of the basic extractor is shown in Fig. 9.5. For this extractor there are N stages in the extracting section, 1E to NE, and there are M stages in the stripping section, 15 to MS. 

Figure 11. Countercurrent multistage extraction with immiscible solvents and constant distribution coefficient. (From firfrac/Zon by R. E. Treybal. Copyright 1963,...

Figure 7.10 Schematic diagram of countercurrent multistage extraction.

Figure 7.11 Countercurrent multistage extraction on a right-triangular diagram.

Figure 7.17 Countercurrent multistage extraction with extract reflux.

With the development in the fermentation broth of concentrations of the order of 500 O.U./cu. cm. total penicillin (80 per cent penicillin-G), the concentration procedures have not required adsorption on activated carbon (158). A presently recommended flowsheet (89) involves continuous, countercurrent, multistage extraction of the filtered and acidified (pH 2 to 2.15) broth with a one-fifth volume of amyl acetate in the centrifugal extractor at room temperature similar extraction into a volume of cold buffer solution (pH 6.8 to 7.0) acidification to pH 2 and reextraction into a K... 

EXAMPLE 12.7-1. Material Balance for Countercurrent Stage Process Pure solvent isopropyl ether at the rate of, = 600 kg/h is being used to extract an aqueous solution of Lq = 200 kg/h containing 30 wt % acetic acid (/4) by countercurrent multistage extraction. The desired exit acetic acid concentration in the aqueous phase is 4%. Calculate the compositions and amounts of the ether extract and the aqueous raffinate L. Use equilibrium data from Appendix A.3. 

Figure 8.1.39. (a) Countercurrent multistage extraction system for a partially miscible system, (b) Ri t triangular diagram for counter-current multistage extraction, solute C being extracted from feed phase containing primarily A by solvent B (here N = 5). 

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