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Liquid-Liquid Extraction: Name: Suman Kumar Paul ROLL NO.: 16AG63R09 M.Tech, Food Process Engineering Iit Kharagpur

Liquid-liquid extraction is a separation process that uses the differences in solubility of compounds across two immiscible liquids. It works based on the partition coefficient principle. There are various modes of operation including single stage batch, continuous multistage countercurrent extraction. Common equipment used are agitated columns, mixer settlers, spray towers. Key parameters that affect extraction include solvent selection, operating conditions, and extractor design. Applications include food, pharmaceutical, and chemical industries. Though widely used, it has limitations such as being time consuming.

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Dnyaneshwar Gawande
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118 views21 pages

Liquid-Liquid Extraction: Name: Suman Kumar Paul ROLL NO.: 16AG63R09 M.Tech, Food Process Engineering Iit Kharagpur

Liquid-liquid extraction is a separation process that uses the differences in solubility of compounds across two immiscible liquids. It works based on the partition coefficient principle. There are various modes of operation including single stage batch, continuous multistage countercurrent extraction. Common equipment used are agitated columns, mixer settlers, spray towers. Key parameters that affect extraction include solvent selection, operating conditions, and extractor design. Applications include food, pharmaceutical, and chemical industries. Though widely used, it has limitations such as being time consuming.

Uploaded by

Dnyaneshwar Gawande
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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LIQUID-LIQUID EXTRACTION

NAME: SUMAN KUMAR PAUL


ROLL NO.: 16AG63R09
M.TECH, FOOD PROCESS ENGINEERING
IIT KHARAGPUR
CONTENTS
 Introduction
 Principle
 Single stage batch extraction
 Continuous multistage counter current extraction
 Liquid-liquid extraction equipment
 Parameters of LLE
 Extraction of soybean oil by LLE
 Applications
 Advantages and limitations
 Conclusions
INTRODUCTION
 Extraction

Extraction is a separation process consisting in the separation of


a substance from a solid or liquid mixture..

 Liquid-liquid extraction

It is a method to separate compounds based on their relative


solubilities in two different immiscible liquids.

 In liquid-liquid extraction the extraction takes place from one


liquid medium to another.
 Feed contains the desired solute.
 Its comes in contact with the solvent.
 Mass transfer takes place.
 The extract is the solvent rich solution contains the extracted
solute.
 The raffinate is the residual feed solution, may contain little
solute.
PRINCIPLE
 It is a mass transfer and thermodynamic process and it works based
on the partition or distribution coefficient.

 Partition Coefficient
It is the ratio of concentrations of a compound in a mixture of
two immiscible phases at equilibrium.
Given as,
𝑪𝑬
𝑲=
𝑪𝑹
Where,
𝑪𝑬 = 𝑒𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 𝑠𝑜𝑙𝑢𝑡𝑒 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑛𝑔 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
𝑪𝑹 = 𝑒𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 𝑠𝑜𝑙𝑢𝑡𝑒 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑟𝑎𝑓𝑓𝑖𝑛𝑎𝑡𝑒
OPERATING MODES OF EXTRACTION

Single stage
Batch
Multistage
Extraction

Counter
Continuous
current
Single Stage Batch Extraction

Multistage Batch Extraction


Continuous Counter Current Multistage
LIQUID-LIQUID EXTRACTION EQUIPMENT

 Vessels in which mixing is done by mechanical agitation


 Agitated columns
 Mixer-settlers
 Centrifugal extractors
 Vessels in which mixing is done by flow of the fluid

 Spray extraction towers


 Packed extraction towers
AGITATED COLUMNS
 Two most important types
a) Scheibel Tower
 The agitators are mounted at fixed intervals on a central
vertical shaft.
 Wire-mesh packings are installed to improve coalescence
and separation of the phases.
b) Karr Reciprocating Plate Tower
 Perforated trays moves up and down.
 More uniform drop size distribution.
Scheible Tower Karr Column
MIXER-SETTLERS
 A mixer-settler device ordinarily
consisted of two parts:
 A mixer for contacting the
two liquid phases.
 A settler for their mechanical
separation.
 It provides efficient mass
transfer.
SPRAY EXTRACTION TOWERS
 The heavy liquid enters at the
top of the spray tower, fills the
tower as the continuous
phase.
 The light liquid enters through
a nozzle distributor at the
bottom, which disperses or
sprays the droplets upward.
 The light liquid coalesces at
the top and flows out.
 In some cases the heavy liquid
is sprayed downward into a
rising, light continuous phase.
PARAMETERS OF LLE

 Solvent selection
 Operating conditions
 Mode of operations
 Extractor type
 Design criteria
SOLVENT SELECTION
 Partition coefficient
 High selectivity
 Density
 Interfacial tension
 Viscosity
 Stability
 Cost
 Toxicity and flammability
 Corrosivity
APPLICATIONS
 In Food Industry
 Extraction of essential oil, flavourings etc.
 Caffeine extraction from tea and coffee.

 Other applications:
 Removal of phenol from waste water.
 Recovery and purification of acetic acid from aqueous streams.
 Extraction of antibiotics and organic acids from fermented
broth.
 Recovery of rare earth elements.
DEACIDIFICATION OF SOYBEAN OIL
 Degummed soybean oil containing 1.05 ± 0.10% w/w free
fatty acids.
 Deacidification is done to remove this free fatty acids.
 It provides more stability and make it more acceptable for
consumers.
 It is done by extraction with ethanol.
 degummed soybean oil is used as the feed.
 Extract contains ethanol with FFAs.
 Raffinate contain the deacidified oil.
Advantages
 Heat sensitive products are processed at ambient or
moderate temperatures.
 Suitable at wide range of temperature.
 Very large capacities are possible with a minimum of
energy consumption
 Recovery of solvent is possible.

Limitations
 Time consuming.
 Required skilled labor.
CONCLUSION
 LLE is used when separation not feasible by distillation.
 It is a mass transfer and thermodynamic process.
 Selection of solvent is very important parameter for LLE.
 This method is widely used in various industries, and in the
laboratory for refining, isolating and purifying a variety of
useful compounds.
 Though it is widely used, it has some limitations.
REFERENCES
1. Geankoplis, C.J., Transport Processes and Unit Operations, 4th edition,
Prentice Hall of India, ISBN 81-203-2614-8, 2004.
2. Ghosh, R., Principles of Bioseparations Engineering, World Scientific
Publishing Co. Pte. Ltd., ISBN 981-256-892-1, 2006.
3. McCabe, W.L., Smith, J.C., Harriott, P., Unit Operations of Chemical
Engineering, 5th ed., McGraw-Hill, ISBN 0-07-112738-0, 1993.
4. Green, W. D., Perry, H.R. (eds.), Perry’s Chemical Engineers’ Handbook,
8th edition, McGraw-Hill, ISBN 0-07-142294-3, 2008.
5. Fornasero, L. M., Marenchino, N.R., and Pagliero, L.C., Deacidification
of Soybean Oil Combining Solvent Extraction and Membrane Technology,
Advances in Materials Science and Engineering ,Volume 2013 , Article ID
646343, 5 pages, 2103.

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