Contact extraction

A 50 per cent solution of solute C in solvent A is extracted with a second solvent B in a countercurrent multiple contact extraction unit. The mass of B is 25 per cent that of the feed solution, and the equilibrium data are ... 

Figure 13.13. Arrangement for multiple-contact extraction in countercurrent flow...

Most people probably regard extracts as having their origins in medicinal usage, and it is from this tradition that some of the more established extract manufacturers have evolved. Familiarity with the descriptions of various traditional extracts may help to avoid misunderstandings when contacting extract manufacturers. 

Counter-Current Distributions. A special multiple-contact extraction is needed to eflect the separation of two substances whose D values are very similar. In principle, counter-current distribution (CCD) could be carried out in a series of separatory... 

Fig. 6.5. Single-contact extraction with solvent recovery.

Fig. 6.10. Single-contact extraction and solvent recovery on Janecke coordinates.

Distribution Diagram. Although computations for single-contact extraction can be carried out on distribution-diagram coordinates, it is inconvenient because a trial-and-error solution is required hence description of this method is omitted. 

This process is an extension of single-contact extraction, wherein the raffinate from the first stage is extracted with fresh solvent of the same composition in successive stages, as the flowsheet of Fig. 6.I80 indicates, the concentration of C in the raffinate thus being further reduced. Different quantities of solvent may be used in the various stages. 

Illustration sy Onc hundred pounds of a 50% acetone (C)-50% water (A) solution is to be reduced to a 10% solution of acetone by extraction with 1,1,2-trichloroethane (B) in a cocurrent multiple-contact extraction system. Twenty-five pounds of solvent is to be used in each stage. Calculate the number of stages and concentration of extracts. The temperature is to be 25°C. 

Single-contact Extraction. These calculations were first described by Hunter (10). Refer to Fig. 7.1. On tetrahedral diagrams of this sort, the geometrical rules applicable to mixtures on ternary triangular diagrams apply. Consequently, if feed solution F, a solution of components A and By is extracted with solvent S, a solution of C and D, the point M representing the mixture as a whole is on the straight line FS, such that... 

One hundred pounds of a solution containing 20% acetic acid, 80% water are to be extracted with methyl isobutyl ketone as solvent, at 25 C. Equilibrium data of Sherwood, Evans, and Longcor are available in [Ind. Eng. Chem. 31, 1144 (1939)]. a. For single-contact extraction,... 

Nondispeisive phase contact Extraction of products in fermentation process producing ethanol and acetone-butanol-etha-nol (ABE) (microporous/porous hydrophobic membranes)... 

The diagrams are useful in studying single-contact or concurrent multiple-contact operations (Example 11-1) but are not well suited to the study of countercurrent multiple-contact extractions. 

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