Supercritical fluid Extraction
and it’s Applications
Dr S. N. Naik
Center For Rural Development and
Technology
IIT Delhi
Outline
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Supercritical fluid as a solvent
Application of supercritical fluids
Supercritical carbon dioxide extraction of botanicals
Particle design using supercritical fluid
Biomass conversion using Supercritical fluid
SCF based Bio refinery
Supercritical fluid as a solvent
• Solvent are used in large amount in chemicals,
pharmaceutical, food and natural products
industry
• In search of environmental friendly solvent,
attentation has been paid to supercritical fluid
for wide application in extraction,chromatograhy,
particle design, reaction, drying etc.
Physical properties of gas ,liquids and supercritical fluids
Typical Supercritical Solvents
Compound
Tcº C
Pc atm
d*
CO2
31.3
72.9
0.96
C2H4
9.9
50.5
---
N2O
36.5
72.5
0.94
NH3
132.5
112.5
0.40
n-C5
196.6
33.3
0.51
n-C4
152.0
37.5
0.50
CCl2F2
111.8
40.7
1.12
CHF3
25.9
46.9
----
H2O
374.1
218.3
----
Advantages of SCF
Application of SCF
Extraction of value added Chemicals from Biomass
Bioactive compounds from Botanicals
Particle design using supercritical
fluid
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Pharmaceutical, Nutraceutical, Cosmetic, Specialty chemistry industry
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RESS: Rapid Expansion of Supercritical Solutions
Consist in solvating the product in the fluid and rapidly depressurizing this
solution through an adequate nozzle(<100micro m to 20 micro m diameter)
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Attractive due to the absence of organic solvent use
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Its application is restricted to products that present a reasonable solubility
in supercritical carbon dioxide(low polarity compounds)
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GAS or SAS: Gas(or Supercritical fluid) Anti-Solvent
Consist in decreasing the solvent power of a polar liquid solvent in which the
substrate
is dissolved, by saturating it with carbon dioxide in supercritical conditions,
causing the substrate precipitation or recrystallization
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Rapid expansion of supercritical
solutions (RESS)
• Depressurizing this solution through a heated nozzle into a low
pressure chamber in order to cause an extremely rapid
nucleation of the substrate(s) in form of very small particles
• In the precipitation unit, the supercritical solution is expanded
through a nozzle that must be reheated to avoid plugging by
substrate(s) precipitation
• The morphology of the resulting solid material both depends
on the material structure crystalline or amorphous, composite
or pure.
• The RESS parameters;
• temperature, pressure drop, distance of impact of the jet
against the surface,
• dimensions of the atomization vessel, nozzle geometry
RESS Process
• RESS is a very attractive process as it is simple and relatively easy to
implement at least at small scale when a single nozzle can be used.
• Extrapolation to a significant production size requires either a multinozzle system or use of a porous sintered disk through which
pulverization occurs,
• In both the case, particle size distribution is not easy to control and
may be much wider than in the case of a single nozzle.
• Particle harvesting is complex
• The most important limitation of RESS development lies in the too
low solubility of compounds in supercritical fluids
• In most cases, use of a co-solvent to increase solubility in the fluid is
not feasible
Supercritical anti-solvent and
related process (GAS/SAS)
• In this process, the supercritical fluid is used as an anti-solvent that
causes precipitation of the substrate(s) dissolved initially in a liquid
solvent.
• A batch of solution is expanded several-fold by mixing with a dense
gas in a vessel.
• Due to the dissolution of the compressed gas the expanded solvent
has a lower solvent strength than the pure solvent.
• The mixture becomes supersaturated and solute precipitates in
microparticles.
• This process has been called gas anti-solvent(GAS) or supercritical
anti-solvent(SAS) recrystallization
GAS/SAS Antisolvent Process
• Spraying the solution through an atomization
nozzle as fine droplets into compressed
carbon dioxide.
• The dissolution of the supercritical fluid into
the liquid droplets is accompanied by a large
volume expansion and, consequently a
reduction in the liquid solvent power causing
a sharp rise in the supersaturation within the
liquid mixture and the consequent formation
of small and uniform particles. This spray
process has been called Aerosol solvent
extraction system (ASES) process
ASES Process
Biomass conversion using
Supercritical fluid
Cellulose degradation pathways by SCW
Dielectric constant and Density of Water at 1000 C
Ion product of Water
Hydrolysis of cellulose in SCW
Potential reaction products from the decomposition of
Lignin
Bio refinery
• Bio refinery involves sustainable processing of biomass
into a spectrum of value added products
• Bio-based chemicals, materials, food, feed etc.
• Bio energy (biofuels, power and heat)
• Bio refinery value chain: Biomass production,
conversion, recycling, conformity of end products to
user requirement
Bio-refinery
Secondary metabolites
(terpenoids, alkaloids,lipids)
Biomass
Hemicellulose
Cellulose
Lignin
Ash
Bio-fuels and Chemicals
Supercritical Fluid based Biorefinery
Advantages of Bio-refinery
• Conservation of fossil resources
• Renewable resources are CO2 neutral
• Products are bio-degradable
• Raw materials are non-toxic
Producing chemicals from bio-mass
requires newer clean technology
Extraction of Minor Constituents
Waxes
COSMETICS,
COATINGS, ETC..
Polycosanols/ sterols
Long chain alkanes
OH
n
HO
CHOLESTEROL REDUCING
AGENTS
n
INSECT
SEMIOCHEMICALS
Major Constituents conversion
HEMICELLULOSE
(25-35%)
OH
H
O
HO
HO
H
OH
H
O
H
H
H
H
HO
H
OH
O
HO
H
H
OH
OH
H
OH
HO
OH
H
HO
H
H
H
OH
OH
Ethanol, lactic
acid,furfural derivatives,
glucose, xylose
D-glucose
D-galactose
D-Mannose
O
H
Energy
H
H
HO
HO
H
H
H
O
HO
H
OH
D-xy lose
OH
H
H
HO
OH
H
H
O
OH
H
H
OH
D-arabinose
O
HO
HO
H
H
H
OH
D-glucuronic acid
LIGNIN
CELLULOSE
Vanillin and
analogues
PAPER, strawboard
(15-20%)
(45-55%)
products, plastics
MINOR CONSTITUENTS
(5-10%)
OH
H
Production of biooil via fast pyrolysis process
Feedstock
Biooil
Char
Quench liquid
Recycled gases
Feedstock
Cyclone/
Char Collector
Pyrolysis
reactor
Quench system
Bio-oil storage
Wood
Bio-oil
100 cm3 of wood contains the same energy as 20 cm3 of Bio-oil
SC-CO2 Extraction of
Bio-oil (set-up and
samples)
Up gradation of Bio-oil using SCF
Biooil as such can not be used as transportation fuel
as it contains high percentage of water (~ 45 wt %).
 Also, water decreases its calorific value,
 It forms azeotrope with organic compounds,
 It increases percentage of oxygen and results in
polymerization at room temperature in few weeks.
Methods for removal of water:
 Solvent extraction
 Supercritical CO2 extraction (Green process)
Proximate analysis and calorific value of
mixed biomass (wt. %)
wt %
Moisture
Content
Ash
Content
Volatile
Content
Fixed
Carbon
8.3
1.8
83.0
6.9
Measurement error : ± 0.2
Calorific value = 18.6 MJ/kg
Chemical Analysis of mixed Biomass
C/H/N/S/O analysis results
wt %
C
H
N
S
O
46.70
6.20
0.07
0.05
46.00
Ca
Al
P
ICP-MS of major compounds in ash
Fe
ppm
Mg
59,491 13,300 74,430 39,111
5,787
Composition of Biomass*
• Hemi-cellulose
34.1 ± 1.2 wt %
• Cellulose
44.4 ± 1.4 wt %
• Lignin
21.5 ± 1.0 wt %
* Calculated using acid (dilute H2SO4) –process and HPLC analysis
Comparative XRD analysis of mixedbiomass, cellulose and lignin
Intensity
a: biomass
b: lignin
c: cellulose
2Ф
Biomass has crystalline character due to the presence of cellulose
m (μg)
Comparative TG Analysis of biomass,
cellulose and lignin
T (oC)
The range of main weight loss for biomass is 200-550 oC.
DTG (μg/min)
Comparative DTG Analysis of biomass,
cellulose and lignin
T (oC)
100oC< loss of easily volatiles, 100-130oC (water), 250-320oC (hemicellulose),
300-400oC (cellulose) and 250-750oC (lignin)
HPLC Analysis (NREL Method) of
structural Carbohydrate in Biomass
wt %
Glucose
Xylose
Galactose
Arabinose
Mannose
56.4
± 0.2
6.3
± 0.5
1.9
± 0.1
31.8
± 0.7
3.6
± 0.6
Supercritical CO2 Extraction process of bio-oil
produced from mixed biomass
• 50 g of bio-oil was mixed with 2 mm glass beads and
placed in the extractor to half of its volume.
• Extraction was carried out at 40oC with CO2 flow rate of
40 mL/min
• The first fraction was collected at 10 MPa (100 atm) and
was continued for 2 h
• Then pressure was raised to 25 MPa and the extraction
was continued for 2 h to collect the second fraction.
• The remaining oil was again treated in the same way at
30 MPa to collect the third fraction.
Conclusions
• SC-CO2 extraction process can be used for separation
of bioactive compounds from botanicals.
• Supercritical fluid based biorefinery can be used to
produce value added chemicals and 2nd generation
biofuel from lignocellulosic biomass
• The upgraded bio-oil can be used for production of
clean fuel.
• SCW can be used for conversion of lignocellulosic
biomass to water soluble fermentable sugars for
production of bio-ethanol and chemicals.
Email: snn@iitd.ernet.in