This document discusses liquid-liquid extraction in the food industry. It defines liquid-liquid extraction as a process that removes solutes from one liquid phase into another, without vaporization. Common examples given are separating penicillin from broth and aromatic hydrocarbons from paraffins. A diagram shows a countercurrent liquid-liquid extraction process, where feed and solvents are introduced on opposite sides and exit with different solute concentrations. Key factors in solvent selection are its ability to dissolve the desired solute more than the diluent, being immiscible with the diluent, and having other desirable properties. Types of extraction equipment and determining equilibrium stages are also briefly covered.

1. A.D.Patel Institute of
Technology
 Subject :- Food Engineering Operation - II ( 2161403 )
 Topic :- Liquid Liquid Extraction in Food Industry
 Dept. :- Food Processing Technology
 Prepared By :- Jemishkumar Parmar ( 170010114024 )
Akshar Patel ( 170010114026 )
 Submitted To :- Dr.P.M.Ganorkar & Dr.Ksitiz Kumar

2. Liquid Liquid Extraction
• Extraction is a process where one or more
solutes are removed from one liquid
phase/carrier/diluent by transferring the
solutes to another liquid phase/solvent.
• No vaporisation is needed
• Extraction can be performed at low
temperatures

3.  In this extraction process, the feed, which contains carrier
and the solute is sent to the extraction unit.
 A solvent is also fed into the extractor, with the purpose
to remove the solute from the carrier.
 The extract phase (or the loaded solvent) is then sent to
the solvent recovery unit, to
 separate the desired solute from the extract phase.
 recover the solvent, which can be reused or recycled to be
used again as the solvent.

4. Examples of the uses of extraction
are
• The separation of penicillin from the broth
(the liquid phase obtained from biological
processes).
• The separation of aromatic-ring hydrocarbons
(e.g., benzene, toluene) from paraffins using
sulpholane.

5. A schematic diagram of a complete
liquid-liquid extraction process

6. • In the extraction process, the feed, which
contains the first solvent (or the diluent) and
the solute is sent to the extraction unit (or the
extractor).
• Another solvent (commonly called the solvent)
is also fed into the extractor, with the purpose
to remove the solute from the diluent.

7. Continue
• Normally, the diluent + the remaining solute
is called the raffinate phase, while the second
solvent + the solute is called the extract
phase.
• The extract phase (or the loaded solvent) is
then sent to the solvent recovery unit, to :
• Separate the desired solute from the extract
phase.
• recover the second solvent, which can be
reused or recycled to be used again as the
solvent

8. Types of extraction equipment

11. A schematic flow chart of the
countercurrent
extraction process

12. • In this counter-current extraction system, the
raffinate and extract phases are fed into the
system in the opposite directions.
• In above fig. the raffinate phase consisting of
the solute A and the diluent D is fed into the
system from the right hand side (RHS), with
the total flow rate of o R (or R) and the
concentration (in mole or mass fraction of the
solute) of o x ; note that the flow rate of just
the diluent is D F

13. • The extract phase consisting of pure solvent
• S or the solvent S with some amount of
solute
• A, with the total flow rate of EN+1 (or E ) and
the concentration (in mole or mass fraction of
the solute) of yN+1 is fed into the system from
the left hand side (LHS); note that the flow
rate of just the second solvent is FS.

14. • The raffinate phase exits the extraction system
with the concentration of the solute of xN ,
while the extract phase leaves the system with
the concentration of y1.
• The selection of the (second) solvent is very
crucial for the extraction system
Generally, the solvent should
• be able to dissolve the solute more than the
diluent.

15. • be immiscible to the diluent
• be highly selective for the desired solute
• be highly selective for the desired solute
• not be selective for contaminants
Additionally, the solvent should also be
• non-toxic
• non-reactive or chemically stable

16. • non-corrosive
• non-flammable or non-explosive
• readily available
• Inexpensive
• environmentally friendly (i.e. “green”)

17. Liquid Liquid Extraction
( LLE )

18. The construction of the operating
lines and the location of the operating point

19. The determination of equilibrium
stages for a partially miscible extraction system

20. Reference
• “Separation Process Engineering” by Wankat,
2007