Solvent extraction with multiple stages, fresh solvent

Again there are two extractable species with different distribution coefficients. As before the purity will change as the extract enriches one organic compound more than the other. This exercises assumes that the concentrations of the desired material and the impurity are equal at the start.

Fresh solvent is used at each stage, and the organic phase is separated and pooled with the previous extracts. Keep clicking on Perform calculation to advance through stages.

Enter Kd: Enter a lower Kd for the impurity:
Enter the ratio of organic solvent to water:
Stage: Product in this stage: Overall product:
Composite purity:

What you should learn: Using fresh solvent to extract again will recover the material, but it can take many stages when the distribution coefficient is unfavorable. The composite purity declines because you are also getting a high yield of the impurity.

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School of Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180