The document discusses liquid-liquid extraction, highlighting its advantages over distillation, such as lower energy consumption and effectiveness in separating azeotropic mixtures. It outlines the process stages, types of solvent configurations, and key factors in selecting solvents based on properties like selectivity and recoverability. Additionally, it describes equipment used in the extraction process and various stage definitions for effective separation.

1. TOPIC :
LIQUID-LIQUID
EXTRACTION
Branch: B.E.Chemical

2. Separation
Techniques
Distillation
Crystallization
Salting Out
Solvent
Extraction

3. Why liquid-liquid extraction
 When difference in Boiling Point of two component is very low.
 For azeotropic mixtures.
 To avoid thermal decomposition.
 It consumes Lower Energy than the distillation.
 If proportion of one component is very less then other and it have high
boiling point.
1- Separation is done according to different in solubility .
2- Problem with L-L extraction that we mix then we separate.
IMP Notes:

4. What is liquid-liquid extraction
Solvent
Feed Raffinate
Extract
SeparationContact

5. What is liquid-liquid extraction
As Inlet:
 Solute + Inert
 Solvent
As Outlet:
• Extract
• Raffinate
Each stage contain:
 Contact
 Separation

6. Equilateral Triangular Co-
Ordinates

7. Equilateral Triangular Co-
Ordinates

8. Types of ternary systems
1) Formation of one pair of partially soluble liquids.
[closed ternary diagram]
2) Formation of two pair of partially soluble liquids.
[open ternary diagram]

9. Formation of one pair of partially miscible
liquids
 AC&BC are completely soluble.
 AB is partially soluble.
 M will be separated to two
compositions; N & L
 If C is solvent for A so as C increases,
L goes up till P(Plait Point) at which
A,B & C become one phase. This is
done due to the increase in mutual
solubility between A&B.
C
BA
P
II
I
M
N
L

10. Formation of one pair of partially miscible
liquids
 Equilibrium relation.
Effects:
1) Effect of TEMPERATURE
2) Effect of PRESSURE
x
y
P

11. Formation of two pair of partially miscible
liquids
 A-B & C-B are partially soluble.
 A is completely soluble in C.

12. Formation of two pair of partially miscible
liquids
Effects:
1) Effect of TEMPERATURE
2) Effect of PRESSURE

13. Multi Component System
 In this type of system there are >=4 components in which 2 are solute and 2
are solvents. So it is known as multi component system.
 E.g: the distribution of formic acid and acetic acids between the partly
soluble solvents water and carbon tetrachloride. But this type of system
representation requires 3D graph which is very difficult to understand. So
Generally it is not used.

14. Choice Of Solvent
1) Selectivity
2) Distribution Co-efficient
3) Insolubility of solvent
4) Recoverability
5) Density
6) Interfacial Tension
7) Chemical Reactivity
8) Viscosity, Vapor Pressure, Freezing Point
9) Non Toxic, Non Flammable, & low cost.

15. Stage definition
 It is a mechanical device or series that allow the solvent
& solution to contact and separate. So; stage is:

16. SINGLE STAGE

17. 1
V0, y0
L1, x1L0, x0
V1, y1
V0+L0=V1+L1=M
V0y0+L0x0=V1y1+L1x1=MxM
are on the same straight line y0, x0, xM
are on the same straight line y1, x1, xM
SINGLE STAGE

18. Multi stage cross current

19. Multi stage cross current
1 2
L0, x0 L1, x1 L2, x2
V0, y0 V0, y0
V2, y2V1, y1
y0, x0, xM1 are on the same straight line are on
the same straight line y1, x1, xM1
y0, x1, xM2 are on the same straight line are on
the same straight line y2, x2, xM2

20. MULTI STAGE COUNTER CURRENT
1 n
L0, x0 L1, x1 Ln, xn
V1, y1 Vn, yn Vn+1, yn+1
Vn+1+L0=V1+Ln=M
Vn+1yn+1+L0x0=V1y1+Lnxn=MxM
L0-V1=Ln-Vn+1=R
No. of stages = n+(a/a+b)
But get a & b from AB line

21. EQUIPMENT:
 Different mechanical devices are used in liquid-liquid extraction such as:
1. The simplest is a mixer/settler, or decanter, in which the two liquid phases
are separated.
2. Plate towers, packed towers, and mechanically agitated mixers (rotating
disk contactors)

22. Extractor/stripper process

23. 1. Mixer/ Settler
Mixing vessel with variable-speed turbine
agitator
Horizontal gravity-settling vessel

24. Types of Impeller In Mixer

25. 2. Spray column

26. 3. Packed column

27. 4. Tray Column: