Microwave-assisted extraction is an efficient extraction method that allows compounds to be extracted more rapidly from plants with similar or better yields than conventional extraction methods. It works by transferring microwave energy to the solvent and plant matrix, rapidly heating them and breaking open the plant cells to release compounds into the solvent. Supercritical fluid extraction uses solvents like carbon dioxide above their critical temperature and pressure, giving them liquid-like densities and gas-like transport properties for efficient, non-toxic extraction.

1. EXTRACTION Dr. Kalaskar Mohan G

2. MICROWAVE ASSISTED
EXTRACTION
 Microwave-assisted extraction is an efficient
method for deriving natural compounds from
raw plants.
 Microwave extraction allows organic
compounds to be extracted more rapidly,
with similar or better yield as compared to
conventional extraction methods.
Plant Solvent
Microwave
extraction
Conventional
extraction
Time
(min)
Yield (%) Time (min)
Yield
(%)
Silybus
marianum
Ethanol
4 1.37 55 1.28
Artemisia
annua
Chlorofor
m
2 024 60 0.15

3. MICROWAVE ASSISTED
EXTRACTION
 Basic of this technique is
 rapid transfer of energy to solvent and solid plant matrix
 resulting to subsequent heating of the solvent and solid matrix,
efficiently and homogeneously.
 Components of the sample or solvents absorb microwave
energy in accordance to their dielectric constants.
 When plant material is immersed inside a microwave
transparent solvent, the heat of microwave radiation directly
reaches to the solid without being absorbed by the solvent,
resulting in instantaneous heating of the residual moisture in
the solid.
 Heating causes the moisture to evaporate and creates a high
vapour pressure that breaks the cell wall of substrate and
releases the content into solvent.
 The extracting selectivity and the ability of the solvent to
interact with microwaves can be modulated by using
mixtures of solvents.
 One of the most commonly used mixtures is hexane-
Theory

4. MICROWAVE ASSISTED
EXTRACTION
 Both systems are
available as multi-
mode and single-
mode.
 A multi-mode
system allows evenly
radiation of sample
by random
dispersion of
microwaves.
 Single-mode (aka
focused system)
allows focused
radiation on a
restricted zone by a
much stronger
electric field.
Open vessel and closed vessel system
INSTRUMENTS
Both multi-mode and focused system comprises of the following
four components:
Microwave generator: magnetron which generates microwave
energy
Wave guide: propagates microwave to microwave cavity

5. MICROWAVE ASSISTED
EXTRACTION

6. MICROWAVE ASSISTED
EXTRACTION
 The MAE process is as follows:
 Microwave radiation
 Moisture get heated up
 Moisture evaporates
 Generation of tremendous pressure on cell wall
 Swelling of plant cell
 Rupture of the cell
 Leaching out of phyto-constituents
 This phenomenon can be intensified if the plant
matrix is impregnated with solvents with higher
heating efficiency under microwave.
Process

7. MICROWAVE ASSISTED
EXTRACTION
 Advantages
 It reduces solvent consumption,
 It has a shorter operational time,
 It possess moderately high recoveries,
 Has a good reproducibility and minimal sample
manipulation for extraction process.
 Disadvantages
 Furthermore, the efficiency of microwaves can
be very poor when either the target compounds
or the solvents are non-polar, or when they are
volatile.

8. Supercritical Fluid Extraction
For every substance, there is a critical temperature
(Tc) and pressure (Pc) above which no applied pressure
can force the substance into its liquid phase. If the
temperature and pressure of a substance are both
higher than the Tc and Pc for that substance, the
substance is defined as a supercritical fluid.
Triple point
0.01oC/ 42 bar
Critical point
374oC/ 218 bar

9. PROPERTIES OF SCFS
At the critical point, the
density of the gas and
liquid phases is the same;
there is no distinction
between the phases. i.e.
between those of the pure
liquid and gas.
Supercritical posses
densities that are liquid-
like and transport
properties that are gas-
like.
these offers good
penetrative ability and
good extractive ability.
For CO2:
Triple point: pressure: 52.8bar
temperature: -56.60C
Critical point pressure: 73.8bar
temperature: 31.06 0C
Supercritical Fluid Extraction

10. Choice of SCFs solvent
 Good solublizing and penetrating property
 Inert to the product
 Easy separation from the product
 Cheap
 Low CP because of economic reasons
Supercritical Fluid Extraction

11. Carbon dioxide is the most commonly used SCF, due
primarily to its low critical parameters (31.1°C, 73.8
bar),
low cost and non-toxicity.
However, several other SCFs have been used in both
commercial and development processes. The critical
properties of some commonly used SCFs are ;
Fluid Critical Temperature (0 C) Critical Pressure (bar)
Carbon dioxide 30.41 73.8
Ethane 30.54 48.8
Ethylene 28.24 50.4
Propane 36.98 42.5
Propylene 36.49 46.0
Trifluoromethane (Fluoroform) 29.93 48.6
Chlorotrifluoromethane 30.20 38.7
Supercritical Fluid Extraction

12. SUPERCRITICAL FLUID
EXTRACTION PROCESS
 An extraction medium (going to be SCF) stored in the feed tank
and liquid SCF is pumped from a reservoir ; it is heated and
pressurized to reach the supercritical conditions to extractor.

13.  Supercritical SCF enters
the extraction chamber
where contact with crude
drug bed occurs and the
more volatile substances
are dissolved into the
supercritical fluid.
 Solute and SCF leave
extractor and extract is
precipitated in
separators, where SCF
becomes gaseous.
 Gas is recycled by
condensation before
returning to liquid
reservoir.
SUPERCRITICAL FLUID
EXTRACTION PROCESS

14. ADVANTAGES & DISADVANTAGES OF SCFE
Some of the advantages and disadvantages of SCFs compared to
conventional liquid solvents for separations:
• Dissolving power of the SCF is controlled by pressure and/or
temperature
• SCF is easily recoverable from the extract due to its volatility
• Non-toxic solvents/gases leave no harmful residue
• High boiling components are extracted at relatively low
temperatures
• Separations not possible by more traditional processes can
sometimes be effected
• Thermally labile compounds can be extracted with minimal
damage as low temperatures can be employed by the extraction
Advantages
Disadvantages
 Elevated pressure required
 High capital investment for equipment

15. APPLICATIONS OF SUPERCRITICAL FLUID
EXTRACTION
Supercritical Fluids
(SCF’s) are
increasingly
replacing the organic
solvents that are
used in industrial
purifications and
recrystallization
operations because
of regulatory and
environmental
pressures on
hydrocarbons and
ozone depleting
emissions.

16. APPLICATIONS OF SUPERCRITICAL FLUID
EXTRACTION
 Food and flavouring
SFE is applied in food and flavouring industry due to no
residual solvent.
 Decaffeinication of tea and coffee.
 extraction of essential oils and aroma materials from spices.
 in extracting some edible oils and producing cholesterine-free egg
powder.
 Pharmaceutical industy
Producing of active ingradients from herbal plants for avoiding
thermo or chemical degradation. Elimination of residual
solvents from the products.
 Other plant extractions
Production of denicotined tobacco.
 Enviromental protection

17. APPLICATIONS OF SUPERCRITICAL FLUID
EXTRACTION
Applications of SCF include
 recovery of organics from oil shale
 separations of biological fluids
 bioseparation
 petroleum recovery
 crude dewaxing
 coal processing (reactive extraction and liquefaction)
 selective extraction of fragrances, oils and impurities
from agricultural and food products
 pollution control
 combustion and many other applications.