Liquid Liquid Extraction

This PPT contains Basics and Detail study of Liquid Liquid Extraction.....one of the unit operation in Mass Transfer. Also contains solvent selection criteria.

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

2. 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:

3. What is liquid-liquid extraction Solvent Feed Raffinate Extract Separation Contact

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

5. Equilateral Triangular Co-Ordinates

6. Equilateral Triangular Co-Ordinates

7. 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]

8. 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 B A P II I M N L

9. Formation of one pair of partially miscible liquids Equilibrium relation. Effects: Effect of TEMPERATURE Effect of PRESSURE x y P

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

11. Formation of two pair of partially miscible liquids Effects: Effect of TEMPERATURE Effect of PRESSURE

12. 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.

13. Choice Of Solvent Selectivity Distribution Co-efficient Insolubility of solvent Recoverability Density Interfacial Tension Chemical Reactivity Viscosity, Vapor Pressure, Freezing Point Non Toxic, Non Flammable, & low cost.

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

15. Single stage

16. 1 V , y L 1 , x 1 L , x V 1 , y 1 V +L =V 1 +L 1 =M V y +L x =V 1 y 1 +L 1 x 1 = Mx M are on the same straight line y 0, x 0, x M are on the same straight line y 1, x 1, x M Single stage

17. Multi stage cross current

18. Multi stage cross current 1 2 L , x L 1 , x 1 L 2 , x 2 V , y V , y V 2 , y 2 V 1 , y 1 y 0, x 0, x M1 are on the same straight line are on the same straight line y 1, x 1, x M1 y 0, x 1, x M2 are on the same straight line are on the same straight line y 2, x 2, x M2

19. multi stage counter current 1 n L , x L 1 , x 1 L n , x n V 1 , y 1 V n , y n V n+1 , y n+1 V n+1 +L =V 1 +L n =M V n+1 y n+1 +L x =V 1 y 1 +L n x n = Mx M L -V 1 =L n -V n+1 =R No. of stages = n +(a/ a+b ) But get a & b from AB line

20. 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)

21. Extractor/stripper process

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

23. Types of Impeller In Mixer

24. 2. Spray column

25. 3. Packed column

26. 4. Tray Column :

27. THE END THANK YOU