WHAT IS LIQUID LIQUID EXTRACTION? STEPS OF LIQUID LIQUID EXTRACTION SCHEMATIC DIAGRAM OF EXTRACTION PROCESS WHERE WE CAN USE LIQUID LIQUID EXTRACTION TERNARY SYSTEM LIQUID LIQUID EQUILIBRIA EXPERIMENTAL DETERMINATION OF LLE DATA GRAPHICAL REPRESENTATION OF LLE DATA EQUILATERAL TRIANGULAR DIAGRAM EFFECTS OF TEMPERATURE ON ETD RECTANGULAR TRIANGULAR DIAGRAM CRITERIA FOR SOLVENT SELECTION

1. NAME : SAKHARELIYA SHUBHAM A.
ENROLLMENT NO. : 180470105047
BRANCH : CHEMICAL ENGINEERING
SUBJECT : MASS TRANSFER OPERATION - I
LIQUID LIQUID EXTRACTION

2. OUTLINE
LIQUID LIQUID EXTRACTION
 WHAT IS LIQUID LIQUID EXTRACTION?
 STEPS OF LIQUID LIQUID EXTRACTION
 SCHEMATIC DIAGRAM OF EXTRACTION PROCESS
 WHERE WE CAN USE LIQUID LIQUID EXTRACTION
 TERNARY SYSTEM
 LIQUID LIQUID EQUILIBRIA
 EXPERIMENTAL DETERMINATION OF LLE DATA
 GRAPHICAL REPRESENTATION OF LLE DATA
 EQUILATERAL TRIANGULAR DIAGRAM
 EFFECTS OF TEMPERATURE ON ETD
 RECTANGULAR TRIANGULAR DIAGRAM
 CRITERIA FOR SOLVENT SELECTION

3.  WHAT IS LIQUID LIQUID EXTRACTION ?
 IT IS THE MASS TRANSFER OPERATION IN WHICH A SOLUTION IS BROUGHT INTO
INTIMATE CONTACT WITH THE SECOND IMMISCIBLE OR SLIGHTLY MISCIBLE LIQUID
(CALLED SOLVENT) IN ORDER TO SEPARATE SOLUTE FROM LIQUID SOLUTION.

 THE SOLUTE RICH PHASE IS CALLED EXTRACT PHASE AND SOLUTE LEANE PHASE IS CALLED
RAFFINATE PHASE.
A C B
FEED
SOLVENT
SOLUTE
SOLVENT
THE TWO LIQUID
PHASES THAT
HAVE
DIFFERENT
DENSITIES ARE
THEN
SEPERATED

4.  STEPS OF LIQUID LIQUID EXTRACTION
 AN EXTRACTION PROCESS INVOLVES FOUR MAJOR STEPS :
 THE BRINGING THE FEED AND SOLVENT INTO INTIMATE CONTACT BY DISPERSING ONE
PHASE INTO THE OTHERS AS DROPLETS.
 SEPERATION OF EXTRACT AND RAFFINATE PHASE THAT HAVE DIFFERENT DENSITIES.
 REMOVAL AND RECOVERY OF SOLUTE FROM THE EXTRACT PHASE IN A RELATIVELY
PURE FORM.
 REMOVAL AND RECOVERY OF SOLVENT FROM EACH PHASE BY DISTILLATION.

5.  SCHEMATIC DIAGRAM OF EXTRACTION PROCESS

6.  WHERE WE CAN USE LIQUID LIQUID EXTRACTION ?
 FEW CASES AT SOLVENT EXTRACTION IS AN ATTRACTIVE SEPERATION TECHNIQUE :
 THE COMPONENTS TO BE SEPARATED HAVE CLOSE BOILING POINTS.
 SEPARATION OF HEAT-SENSITIVE MATERIALS SUCH AS ANTIBIOTICS & VITAMINS.
 RECOVERY OF NON-VOLATILE SOLUTES, USUALLY FROM AQUEOUS SOLUTIONS, IN
HYDRO-METALLURGY.
 RECOVERY OF A SOLUTE FROM A VERY DILUTE SOLUTION.
 REMOVAL OF ORGANICS FROM AQUEOUS STREAMS.

7.  TERNARY SYSTEM
 A LIQUID-LIQUID EXTRACTION SYSTEM CONTAINS AT LEAST THREE COMPONENTS :
 THE SOLUTE (C)
 THE CARRIER LIQUID IN THE FEED (A)
 THE EXTRACTING SOLVENT (B)
 FOR EXAMPLE : PROCESS OF EXTRACTION OF PENICILLIN FROM THE FERMENTATION.
WHERE SOLUTE = C = PENICILLIN
CARRIER LIQUID IN THE FEED = A = WATER
EXTRACTING SOLVENT = B = BUTYL ACETATE
 THE EQUILIBRIUM DATA FOR A LIQUID-LIQUID SYSTEM ARE OF VITAL IMPORTANCE IN
THE SELECTION AND DESIGN OF AN EXTRACTION EQUIPMENT.

8.  LIQUID LIQUID EQUILIBRIA
 LET’S CONFINE OUR DISCUSSION ONLY TO TERNARY SYSTEMS.(THE SOLUTE (C),THE
CARRIER LIQUID IN THE FEED (A) & THE EXTRACTING SOLVENT (B))
 BY IT THREE BINARY MIXTURE CAN BE FORMED : A-B, B-C, C-A
 THE MUTUAL MISCIBILITY BEHAVIOUR OF THE COMPONENTS IN EACH OF THESE
BINARIES DETERMINES THE NATURE OF THE EQUILIBRIUM DIAGRAM FOR THE TERNARY
SYSTEM.
 MOST OF THE TERNARY SYSTEMS FALL IN ONE OF THE FOLLOWING CATEGORIES :
 TYPE I TERNARY SYSTEM
 TYPE II TERNARY SYSTEM
 THE CARRIER AND THE SOLVENT ARE PARTIALLY IMMISCIBLE

9.  LIQUID LIQUID EQUILIBRIA
 TYPE I TERNARY SYSTEM :
 A-C AND B-C ARE MISCIBLE PAIRS AND A-B IS PARTIALLY MISCIBLE PAIR.
 ABOUT 75% OF TERNARY LIQUID SYSTEMS ARE FALL IN THIS CATEGORY.
 TYPE II TERNARY SYSTEM :
 B-C AND A-B ARE ONLY PARTIALLY MISCIBLE AND A-C IS MISCIBLE IN ALL
PROPORTIONS.
 THE CARRIER AND THE SOLVENT ARE PARTIALLY IMMISCIBLE :
 IF SOLUTE CONCENTRATION IS LOW THAN HENRY’S LAW TYPE LINEAR DISTRIBUTION
LAWS APPLIES.

10.  EXPERIMENTAL DETERMINATION OF LLE DATA
 LIQUID-LIQUID EQUILIBRIUM DATA ARE OBTAINED BY MEASURING THE
CONCENTRATIONS OF THE THREE COMPONENTS IN THE TWO LIQUID PHASES IN
EQUILIBRIUM AT A GIVEN TEMPERATURE.
 THE FOLLOWING STEPS ARE FOLLOWED:
 SUITABLE QUANTITIES OF PURIFIED A, B, AND C ARE TAKEN IN AN EQUILIBRIUM CELL
MAINTAINED AT A CONSTANT TEMPERATURE.
 THE CONTENT IS MIXED VIGOROUSLY FOR A SUFFICIENT TIME TO ENSURE
ATTAINMENT OF EQUILIBRIUM.
 THE CONTENT IS ALLOWED TO SEPARATE INTO TWO PHASES.
 SAMPLES ARE DRAWN FROM THE TWO PHASES AND ANALYZED FOR THE
CONCENTRATIONS OF A, B, AND C. BY IT WE GET EXTRACT PHASE AND RAFFINATE
PHASE.

11.  GRAPHICAL REPRESENTATION OF LLE DATA
 IF WE SEE LIQUID LIQUID EQUILIBRIUM DATA THEN THERE IS TERNARY SYSTEM SO
THERE ARE THREE CONCENTRATIONS TERMS OF THE THREE COMPONENTS.
 IF WE EXPRESS IT INTO MOLE FRACTION OR IN MASS FRACTION THEN THE SUM IS
UNITY.
 IF THERE ARE TWO PHASE THEN WE CAN REPRESENT IT INTO NORMAL RECTANGULAR
CO-ORDINATE SYSTEM, BUT HERE TERNARY SYSTEM SO THERE ARE TWO OTHER
TECHNIQUES OF REPRESENTATION OF TERNARY EQUILIBRIUM DATA :
 A 'RIGHT-ANGLED TRIANGULAR DIAGRAM' IN WHICH ONLY TWO CONCENTRATIONS ARE
PLOTTED
 USING RECTANGULAR COORDINATES AND PLOTTING THE MASS FRACTIONS (OR MOLE
FRACTIONS) OF THE SOLUTE AND OF THE SOLVENT IN THE TWO PHASES ON 'SOLVENT-FREE
BASIS'.

12.  EQUILATERAL TRIANGULAR DIAGRAM
• APEX REPRESENTS 100% OF PURE
COMPONENT.
• SIDES REPRESENT MIXTURE OF TWO
COMPONENT.(MOLE PERCENT 0-100%)
• PROPERTIES OF EQUILATERAL TRIANGULAR
DIAGRAM :
 SIDES ARE EQUAL
 ANGLES ARE EQUAL
 MN1+MN2+MN3 = CT
(SUM OF VERTICLE = ALTITUDE OF TRIANGULAR)

13.  EQUILATERAL TRIANGULAR DIAGRAM (TYPE I SYSTEM)
• CURVE RPS  THE EQULIBRIUM DIAGRAM.
• R = SOLUBILITY OF SOLVENT B IN CARRIER
LIQUID A = 0%
• S = SOLUBILITY OF A = 0%
• G1H1, G2H2, G3H3… REPRESENTS TWO
PHASES OF LIQUID WHICH IS IN
EQUILIBRIUM(EXTRACT & RAFFINATE PHASE).
 TIE LINES
• G1, G2, G3  RAFFINATE PHASE  RP ARM
• H1, H2, H3  EXTRACT PHASE  PS ARM
• IF THERE ARE TWO ARMS IN EQUILATERAL
DIAGRAM THEN IT IS CALLED BINODAL CURVE.
• POINT P  TIE LINE  PLAIT POINT

14.  EQUILATERAL TRIANGULAR DIAGRAM (TYPE II SYSTEM)
• A & C ARE COMPLETELY SOLUBLE BUT PAIR
A-B AND B-C SHOWS ONLY LIMITED
SOLUBILITY.
• NO PLAIT POINT
• EXAMPLE :
• A = CHLOROBENZENE
• B = WATER
• C = METHYL ETHYL KETONE

15.  EFFECT OF TEMPERATURE ON E.T.D. TYPE I SYSTEM
• SOLUBILITY OF A & B IS
INCREASE WITH THE
TEMPERATURE
INCREASE.
• AT VERY HIGH
TEMPERATURE A – B
PAIR IS COMPLETELY
SOLUBLE. (POINT P)
• SO INCREASE IN THE
TEMPERATURE WILL BE
DISADVANTAGEOUS
FOR LIQUID LIQUID
EXTRACTION.

16.  EFFECT OF TEMPERATURE ON E.T.D. TYPE II SYSTEM
• AS TEMPERATURE
INCREASE THE
SOLUBILITY OF A & B
AND B & C WILL BE
INCREASE.
• AFTER SOME
TEMPERATURE
INCREASE B & C
BECOME TOTALLY
SOLUBLE TO EACH
OTHER.

17.  RACTANGULAR TRIANGULAR DIAGRAM
QP = RAFFINATE ARM  XB VS XC
PR = EXTRACT ARM  YB VS YC
AB = XC VS YC
P = PLAIT POINT
XC = SOLUTE CONC. IN RAFFINATE
XB = SOLVENT CONC. IN RAFFINATE
YC = SOLUTE CONC. IN EXTRACT
YB = SOLVENT CONC. IN EXTRACT

18.  SOLVENT SELECTION FOR LIQUID LIQUID EQULIBRIA
 THE RIGHT SOLVENT IS THE KEY TO SUCCESSFUL SEPARATION BY SOLVENT EXTRACTION.
 SOLVENTS USED ARE MOSTLY ORGANIC.
 THE IMPORTANT CRITERIA FOR SOLVENT SELECTION ARE GIVEN BELOW :
 SELECTIVITY :
 SELECTIVITY OR PREFERENTIAL UPTAKE OF THE SOLUTE BY THE SOLVENT OVER THE CARRIER IS
THE SINGLE MOST IMPORTANT FACTOR IN CHOOSING A SOLVENT FOR AN EXTRACTION JOB.
 SELECTIVITY OR 'SEPARATION FACTOR' IS DEFINED AS…
 SELECTIVITY OF THE SOLUTE VARIES WITH THE COMPOSITIONS OF THE TWO PHASES IN
EQUILIBRIUM AND DEPENDS ON TEMPERATURE

19.  SOLVENT SELECTION FOR LIQUID LIQUID EQULIBRIA
 CARRIER-SOLVENT IMMISCIBILITY :
 IF THE MUTUAL SOLUBILITY OF THE CARRIER AND THE SOLVENT IS LOW, THEY CAN BE
SATISFACTORILY SEPARATED IN THE SETTLER.
 ONLY A SMALL QUANTITY OF THE SOLVENT WILL BE RETAINED IN THE RAFFINATE AND A SMALL
QUANTITY OF THE CARRIER WILL REMAIN DISSOLVED IN THE SOLVENT.
 SO THE COST OF FURTHER SEPARATION OF THE PHASES BY DISTILLATION OR OTHERWISE WILL
BE SMALL.
 VISCOSITY :
 THE SOLVENT VISCOSITY SHOULD BE LOW,THIS REDUCES POWER CONSUMPTION FOR MIXING
THE PHASES.
 IF THE VISCOSITY OF SOLVENT IS HIGH THEN STRESS WILL BE MORE AND ߡP IS ALSO INCREASE.
SO BECAUSE OF IT PUMPING COST WILL BE INCREASE.

20.  SOLVENT SELECTION FOR LIQUID LIQUID EQULIBRIA
 INTERFACIAL TENSION:
 INTERFACIAL TENSION IS THE FORCE REQUIRED TO KEEP UNIT LENGTH FILM OF FLUID IN
EQUILIBRIUM.
 INTERFACIAL TENSION BETWEEN THE CARRIER AND THE SOLVENT HAS TWO OPPOSING
EFFECTS.
 A LOW INTERFACIAL TENSION FAVOURS FINE DISPERSION OF ONE LIQUID IN THE OTHER,
THEREBY INCREASING THE SPECIFIC INTERFACIAL AREA OF MASS TRANSFER.
 ON THE OTHER HAND, COALESCENCE OF DROPLETS LEADING TO THE SEPARATION OF THE
RAFFINATE AND THE EXTRACT PHASES DOES NOT OCCUR READILY IF THE INTERFACIAL TENSION
IS LOW.
 SO SURFACE TENSION SHOULD NOT BE HIGH AS WELL AS SMALL.IT SHOULD BE OPTIMUM.

21.  SOLVENT SELECTION FOR LIQUID LIQUID EQULIBRIA
 DENSITY :
 THE DRIVING FORCE FOR PHASE SEPARATION IN A SETTLER IS THE DIFFERENCE IN THE
DENSITIES OF THE TWO PHASES.
 THE DENSITY OF THE LIGHTER PHASE SHOULD GENERALLY BE AT LEAST 5% LESS THAN THAT OF
THE HEAVIER PHASE IN ORDER TO ENSURE SMOOTH PHASE SEPARATION.
 CHEMICAL REACTIIVITY :
 THE SOLVENT SHOULD BE CHEMICALLY STABLE AND INERT TOWARD OTHER COMPONENTS OF
THE SYSTEM AND TOWARDS COMMON MATERIAL OF CONSTRUCTION.

22.  SOLVENT SELECTION FOR LIQUID LIQUID EQULIBRIA
 OTHER FACTOR :
 VAPOUR PRESSURE OF SOLVENT SHOULD BE LESS TO CARRIED OUT EXTRACTION AND IT WILL
BE HELPFUL FOR TRANSPORTATION AND EASE OF STORAGE.
 FREEZING POINT OF SOLVENT SHOULD BE LESS AS POSSIBLE.
 THE SOLVENT SHOULD BE LESS EXPENSIVE, NON TOXIC AND NON-CORROSIVE.