## enrichment factor, $$S$$

in liquid-liquid distribution
https://doi.org/10.1351/goldbook.E02127
The factor by which the ratio of two substances in the feed must be multiplied to give their ratio after treatment. $\frac{Q_{\text{A}}}{Q_{\text{B}}} = S_{\text{A,B}}\ \frac{Q_{\text{A}}^{'}}{Q_{\text{B}}^{'}}$ where $$Q_{\text{A}}$$ and $$Q_{\text{A}}^{'}$$ are the final and initial amounts of species A and $$Q_{\text{B}}$$ and $$Q_{\text{B}}^{'}$$ are the final and initial amounts of species B. Hence $$S_{\text{A,B}}=\frac{E_{\text{A}}}{E_{\text{B}}}$$ where $$E$$ is the @F02503@. In terms of $$D$$,$$n$$,$$r$$ (where $$n$$ is the number of stages and $$r$$ the phase ratio), $S_{\text{A,B}} = \frac{1- (1\,+\,r\ D_{\text{A}})^{-n}}{1- (1\,+\,r\ D_{\text{B}})^{-n}}$
Sources:
Orange Book, 2nd ed., p. 90 [Terms] [Book]
PAC, 1993, 65, 2373. (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2382 [Terms] [Paper]