Liquid-Liquid Extraction

Question 1

Liquid-Liquid Extraction

Answer 1

*Components of liquid mixture are separated by contacting it with a suitable liquid solvent
*Raffinate and Extract Streams

Question 2

Example of Liquid-Liquid Extraction

Answer 2

Water - Acetic Acid Separation
*Uses Isopropyl Ether

Penicillin Extraction

Question 3

When to use LLE?

Answer 3

• Distillation is ineffective, a=1
• When one component to be separated has too high a boiling point
   When one of the components is heat-sensitive.

Question 4

Selectivity

Answer 4

Ratio of the concentration ratio of solute (A) to diluent (B) in the extract phase to that in the raffinate phase

Question 5

Assumptions in Liquid-Liquid Extraction

Answer 5

*Isothermal
*Isobaric
*No heat of mixing
*Diluent and solvent are totally immiscible

Question 6

Relationship of Distribution Coefficient and Temperature

Answer 6

Higher T = Higher Distribution Coefficient

Question 7

Distribution Coefficient Equation

Answer 7

(A/g extract) / (A/g raffinate)

Question 8

Wet Scrubber

Answer 8

AKA Spray Towers
*Heavy liquid is sprayed in tower
*Heavy liquid from top displaces equal volume of Light liquid from bottom so it flows from bottom to top

Question 9

Ideal Solvent Characteristics

Answer 9

*Cheap and Available
*HIGH Selectivity
*HIGH Partition Ratio
*HIGH Density Difference and Interfacial Tension
*Recoverable
*Non-Toxic

Question 10

Graphical Methods for LLE

Answer 10

*Janecke Diagrams
*Hunter-Nash Method

Question 11

As temperature increases, area of binodal curve ___

Answer 11

Decreases

Question 12

When solvent dissolves little solute, then ____

Answer 12

large amount if solvent is required