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Supercritical Fluid Extraction and Separation of Biologically Active
Components
Béla SimándiBudapest University of Technology and
Economics
Department of Chemical and Environmental Process Engineering
Historical notes
• 1822 – Baron Cagniard de la Tour
Critical point of a substance
• 1879 – 1880 – Hannay and Hogarth
KI, KBr, CoCl2 in alcohol (TC = 243 °C, PC = 63 bar)
• 1880 - 1920 - van der Waals, Amagat, Joule,
Thomson, Clausius
Pioneer work in research of thermodynamics of one and two component supercritical system
Historical notes
• 1896 – VillardSolubilities of camphor, stearic acid, paraffin wax in methane, ethylene, CO2
• 1943 – Messmore, 1955 - ZhuzeDeasphalting of petroleum oils with propane/propylene (T = 100 °C, P = 100 – 150 bar)
• 1964 – ZoselThe patent includes 68 examples of extractions and separarations
• 1970 – 1980 commercial applications
Supercritical Fluid Extraction (SFE) Units (V > 0.1m3)
SCOPE of presentation
• Physico-chemical properties
• Supercritical Fluid Extraction (SFE)
• SFE of plant constituents
SFE of plant constituents
essential oilstriterpenes and steroidscarotenoidsalkaloidsplant lipids
SCOPE of presentation
• Physico-chemical properties
• Supercritical Fluid Extraction (SFE)
• SFE of plant constituents
• Down stream processing
• Modelling
• Economic issues
• Conclusion
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What is a supercritical fluid?
Supercritical fluid
Density of carbon dioxide vs. pressure
Density of carbon dioxide vs. temperature
Density of water vs. temperature
Range over which near-critical extraction have been carried out
Viscosity of carbon dioxide at the near critical region
Viscosity of water
Specific heat capacity of carbon dioxide
•Bruno and Ely, 1991
Thermal conductivity of CO2
Bruno and Ely, 1991
Transport properties of supercritical solvents
Gas Fluid Liquid
ρ (kg/m3) 1 200 – 700 1000
η (Pas) 10-5 10-4 10-3
D (cm2/s) 10-1 10-3 - 10-4 10-5
Schneider et al., 2000
Fluid phase behaviour
B
A
yA
Phase diagram of ethanol – CO2
•Ploishuk et al, 2001.
The six basic types of fluid phase behaviour
Van Koynenburg and Scott, 1980
The six basic types of fluid phase behaviour
Van Koynenburg and Scott, 1980
The six basic types of fluid phase behaviour
Van Koynenburg and Scott, 1980
High-pressure phase equilibria
),,(),,( i
v
ii
l
i yPTfxPTf =
i
v
iv
i Py
f=φi
l
il
i Px
f=φi
l
ii
v
i xy φφ =
∫∞
−
∂∂−==
≠
V
nVTi
v
ii
i
v
i
RT
PVdV
n
P
V
RT
RTPy
yPTf
ij
ln1
ln),,(
ln,,
φ
22 2
)(
bVbV
Ta
bV
RTP
−+−
−=
P = P(T,V,ni)
The Peng-Robinson equation of state
Kikic, de Loos, 2001
Solubility of solids in supercritical fluids
SFSff 22 =
== ∫
P
P
SVsubSS
sub RT
dPvPff
2
22222 expφ
PyfSFSF
222 φ=
=∫SF
P
P
SV
sub S RT
dPv
P
Py
2
22
22
2
exp
φ
φ
Kikic, de Loos, 2001
Solubility of naphthalene in CO2
Solvating power of supercritical fluids
Critical properties of used solvents
Solvent TC (°C) P C (bar)
Ethylene (C2H4) 9 50,3
Ethane (C2H6) 32 48,8
Propylene (C3H6) 92 46,2
Propane (C3H8) 97 42,4
n-pentane (C5H12) 197 33,7
Benzene (C6H6) 289 48,9
Toluene (C7H8) 319 41,1
Supercritical fluids in food and pharmaindustries
• Carbon dioxide (PC=73.8 bar, TC=31.1°C)
Carbon dioxide
• GRAS (generally regarded as safe)• gentle conditions (PC=73.8 bar,
TC=31.1°C)• inert, odourless, tasteless• easily removed from products• non-explosive• readily available, inexpensive• benign solvent
Supercritical fluids
• Carbon dioxide (PC=73.8 bar, TC=31.1°C)• Nitrous oxide (PC=71.0 bar, TC=36.5°C)• Propane (PC=42.5 bar, TC=96.7°C)
Propane
• near-critical liquid (TC=96.7°C)• flammable, explosive mixtures with air• maximum permitted residue: 50 ppm• significant solvent loss• waste solvent
Supercritical fluids
• Carbon dioxide (PC=73.8 bar, TC=31.1°C)• Propane (PC=42.5 bar, TC=96.7°C)• Water (PC=220.5 bar, TC=374.2°C)
Supercritical fluids
• Carbon dioxide (PC=73.8 bar, TC=31.1°C)• Propane (PC=42.5 bar, TC=96.7°C)• Water (PC=220.5 bar, TC=374.2°C) • Entrainers (ethanol, ethyl acetate,
acetone)
Modifiers (co-solvent, entrainer)
Solvent T C (°C) P C (bar)
n-pentane 196,6 33,7
n-hexane 234,5 30,3
methanol 239,5 80,8
ethanol 241 61,4
n-buthanol 288,9 45
acetone 235 47
Dimethyl ether 126,9 54
Phase diagram of ethanol – CO2
•Ploishuk et al, 2001.
Change of critical parameters by addition of entrainer
Concentration acetone methanol ethanol n-buthanol
mol% Tc(°C) P c(bar) Tc(°C) P c(bar) Tc(°C) P c(bar) Tc(°C) P c(bar)
1 34,7 77,9 32,7 76,5 32,7 76,6 36,5 80,3
2 36,8 79,7 34,7 78,2 35,7 78,3 42,5 87,5
4 43,7 85,7 37,7 81,7 40,5 84,3 56,1 108
•Pure CO2: Tc=31,3°C, Pc=73,8 bar
Developing a Commercial-scale SFE Process
• Analytical/laboratory unit: 1 mL to 1 Lscreening unitsamples for analytical evaluation
• Pilot plant unit: 2 to 100 Lprocessing variablessamples for customers
• Semi-commercial plant: 100 to 200 Lproduction for market tests
• Commercial plant: 200 to 6500 L
Supercritical fluid extraction unit
I. separator
ExtractorCO2 storage
CoolerPumpHeat exchanger
II. separator
Heat exchanger Cooler/
condenser
ValveValve ValveValve
Heat exchanger
Pump process in the T – s diagram
1 liquid
2 undercooler
3 extraction pressure
4 extraction temperature
5 two phase region
5-6 gaseous part
5-7 liquid part
8 gas
Multipurpose extraction unit(NATEX, Austria)
Preparation of raw materials
• Crushing/grinding
Effect of particle size: SFE of paprika
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35
kg CO2/kg dry paprika
Yie
ld (
%)
Run 32
Run 33
Run 34
Run 35
d0 = 0.96 mm
d0 = 0.45 mm
Preparation of raw materials
• Crushing/grinding• Rolling/pelletizing• Wetting/drying
Effect of moisture content: SFE of olive fruit
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140 160
kg CO2/kg dry olive fruit
Yie
ld (
%)
Moisture content: 5.12 %
Moisture content: 47.67 %
Preparation of raw material
• Crushing/grinding• Rolling/pelletizing• Wetting/drying• Chemical/biochemical pretreatment
Extraction conditions
• Pressure• Temperature• Solvent composition (co-solvents)• Extraction time• Solvent flow rate• Upflow/downflow• Packed bed structure (H/D, axial mixing)• Mixing
Separation conditions
• Pressure• Temperature• Multiple separators (fractionation)• Absorbers• Adsorbers • Membranes
Formation of secondary plant products
Process of primary metabolism
CO2 H2O
Pentose cycle
Saccharides
Glycolysis
Phosphoenol-pyruvic acid
Pyruvate
Acetyl CoA
Krebs cycle
CO2
Process of primary metabolism
CO2 H2O
Pentose cycle
Saccharides
Glycolysis
Phosphoenol-pyruvic acid
Pyruvate
Acetyl CoA
Krebs cycle
CO2
Products of primary metabolism
Oligo and polisaccharides
Eritrose-4-PO4
Shikimic acid
Aromatic amino acids
Aliphatic amino acids
Malonyl CoAFatty acids
IPP biological isopren
Squalene
Proteines
Process of primary metabolism
CO2 H2O
Pentose cycle
Saccharides
Glycolysis
Phosphoenol-pyruvic acid
Pyruvate
Acetyl CoA
Krebs cycle
CO2
Products of primary metabolism
Oligo and polisaccharides
Eritrose-4-PO4
Shikimic acid
Aromatic amino acids
Aliphatic amino acids
Malonyl CoAFatty acids
IPP biological isopren
Squalene
Secondary plant metabolism
Glycosides
Mucilages and gums
Phenolic compounds
Lignans
Alkaloids
Fats and waxes
Tetracyclynes
Antraquinones
Alkaloids
Peptides
Terpenes
Terpenoids
Isoprene (C5) units
Isoprene does not participate in the biogenesis
Biosynthesis of Limonene and Carvone
Bouwmeester, H.J. et al.: Plant Physiol., 117, 901-912 (1998).
Terpenoids
• C10 monoterpenes (essential oil)• C15 sesquiterpenes (essential oil)• C20 diterpenes (antioxidants)• C30 triterpenes (phytosterols)• C40 tetraterpenes (carotenes)• (C5)n polyterpenes (caoutchouc)
Solubility
• typical essential oil components
Stahl, E., Quirin, K.-W., Gerard, D.: Dense Gases for Extraction and Refining, Springer-Verlag, Berlin, 1988.
Comparative chemical composition of distilled oils and SFE products
Plant Compound Steamdistillation
SFE
Dill(Anethum graveolens L.)
limonened-carvone
55.736.5
42.648.6
Coriander(Coriandrum sativum L.)
pinenelinalool
15.368.5
7.775.5
Celery(Apium graveolens L.)
limonene3-butylphthalide
50.523.6
33.440.6
Parslay(Petroselinum crispum L.)
α-pineneβ-pinenemyristicin
apiole
24.021.97.438.5
1.53.04.084.9
Alteration of essential oil components during distillation
linalyl acetate → linaloollavandin (Lavandula intermedia Emeric)clary sage (Salvia sclarea L.)
glycosides → thymol
thyme (Thymus vulgaris L.)unknown precursor → α-terpineol
terpinene-4-ol
lavandin (Lavandula intermedia Emeric)pulegone → dihydrocarvone
spearmint (Mentha spicata L.)
Fractionation of fennel oil(Foeniculum vulgare Mill.)
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Fractionation of fennel oil (PE=302 bar, TE=38°C)
1st separator:75 bar, 23.5 °C
1st separator:86 bar, 23.5 °C
Effects of the separation parameters on fractionation of fennel oil
0.75 1 1.5 2 2.5 3 4 5 6 7
P S, bar
TS, °
C
18
22
26
30
34
38
42
68 72 76 80 84 88 92
Composition of orange oil
Component Composition (%)
α-Pinene 0.45
Myrcene 1.77
d-Limonene 90.60
Octanal 0.59
Decanal 0.52
Linalool 0.37
Geranial 0.12
Phase equilibria of orange peel oilBrunner, G.: Industrial Process Development: Counter current Multistage Gas Extraction Processes, Proceedings of 4th International Symposium on Supercritical Fluids, 745-756, Sendai, Japan, 1997.
Separation factors of orange peel oil fractions
x
yK =
Distribution coefficient:
Separation factor:
.frAroma
Terpenes
K
K
−
=α
Brunner, G.: Industrial Process Development: Counter current Multistage Gas Extraction Processes, Proceedings of 4th International Symposium on Supercritical Fluids, 745-756, Sendai, Japan, 1997.
α
Fractionation of citrus oil
CO2
Aroma
CO2
Feed
Terpenes
Results of fractionation
Pilot plant data on deterpenation of orange oil
Aromatic content in feed oil 4.1 %
Aromatic content inconcentrated oil
18.9 %
Recovery of aromatic fraction 90 %
Solvent-to-oil ratio 100
SFE of sesquiterpene lactonesChamomile (Matricaria chamomilla L.)
chamazulene
OH
O
(-)-α-bisabololoxide B
O
OH
(-)-α-bisabololoxide A
OH
(-)-α-bisabolol
O
O
OH
-D-glucose-O
OH
β
apigenin-7-glucoside
O
O
OH
OH
OH
apigenin
OOCOCH3
O
OH
matricine
O
O
trans-en-in-dicycloether
OO
cis-en-in-dicycloether
Fractionated extraction of chamomile
P
(bar)
T
(°°°°C)
Matricine
(%)
αααα-bisabolol
(%)
Spiroether
(%)
Yield
(%)
80 40 3.5 27 14 0.12
90 40 17.0 21.0 16.7 0.4
300 40 7.5 9.2 11.7 1.65
Stahl, E., Quirin, K.-W., Gerard, D.: Dense Gases for Extraction and Refining, Springer-Verlag, Berlin, 1988.
SFE of feverfew (Chrysanthemum partheniumBernh.): effects of pressure and temperature on the
yield
Recovery of parthenolide
O
O
O
parthénolide
Diterpenes investigated by SFE
OOH
OH
O
OH
rosmanol
OH
OH
sclareol
O
OO
OH
O
O
O
OHO ONH OH
O O
O
taxol
baccatin-III
O
H
O O O
OOH
OH
carnosol
OH
O
O
O
H
OHOH
O
O
Isolation of diterpenesfrom plants
Plant Component
Clary sage(Salvia sclarea L.)
sclareol
Yews(Taxus brevifolia Nutt.,Taxus cuspidata Capita)
paclitaxel baccatin III
Rosemary(Rosmarinus officinalis L.),
Sage(Salvia officinalis L.)
rosmanol7-methyl-epirosmanol
carnosol carnosolic acid
Basic sceleton of triterpenes
OH
H
α-amirin
OH
H
β-amirin
OH
OH
faradiol
H
H
OH
β-sitosterol
Isolation of triterpenesPlant Component
Mulberry(Morus alba L.)
α-amyrin acetate
Neem(Azadirachta indica A. Juss)
nimbinsalannin
azadirachtinMarigold
(Calendula officinalis L.)faradiol and its esters
Chaste tree(Vitex agnus castus L.)
β-amyrinβ-sitosterol
Dandelion(Taraxacum officinale Web.)
β-amyrinβ-sitosterol
SFE of dandelion leaves:effects of pressure and temperature on the yields
Recovery of sterols from dandelion leaves
Recovery of carotenoids
OH
OH
lutein (alfalfa)
β-carotene (carrot)
OH
OH
O
capsanthin (paprika)
OH
O
O Obixin (annetto)
lycopene (tomato)
10,589 11,214 11,839 12,464 13,089 13,714 14,339 14,964 15,589 16,214 16,839 17,464 18,089 18,714 19,339 above
SFE of pigments from paprika
Extraction of hop (Humulus lupulus L.)
Water Organic solvent Steam distillation
Water extract Total resin
Petrol soluble Petrol insoluble
‘Hard resin’
Essential oil
‘Soft resin’
α acid β acid Uncharacterised acid
Structure of major componentsOH
R
O
OHOH
O
R
OOH
OH
OOH
OH
R
O
OHO R=
CH3CH3
CH3
CH3
CH3
CH3
CH3CH3
CH3
α acid iso α acid
β acid
Composition of hop extract versus time
Gardner, D.S.: Commercial scale extraction of alpha-acids and hop oils with compressed CO2 inKing, M.B., Bott, T.R. (Eds.):Extraction of Natural Products Using Near-Critical Solvents, Chapman&Hall, Glasgow, 1993.
Chaste tree: Vitex agnus castus L.
p: 100-275-450 bar
T: 40-50-60 °C
Vitex agnus castus L.
Rotundifurane
Diterpene
Vitex agnus castus L.
β-amyrinTriterpenes
β-sitosterol
Vitex agnus castus L.
Casticin
Flavonoid
Vitex agnus castus L.
Minor compounds’ concentration of the extracts [g/kg]:
~3.5x ~3.5x >2.5x >3xsc-CO2/EtOH
Alkaloids: decaffeination of coffee
• Solubilityisobars of caffeine
Stahl, E., Quirin, K.-W., Gerard, D.: Dense Gases for Extraction and Refining, Springer-Verlag, Berlin, 1988.
Decaffeination of green coffee beans
Nearly continuous SFE of coffee
Extraction of nicotine from tobacco
Aroma removal
H2O
Tobacco Nicotine removal
Drying
Adsorbent regeneration
Aroma distribution CO2
Conditioning Nicotine reduced tobacco
CO2
Aroma transfer
Aroma
Nicotine by-product
Extraction of alkaloids used in medicine
Plant Alkaloid Recoverypaprika(Capsicum annuum L.)
capsaicin good
pepper(Piper nigrum L.)
piperine good
poppy(Papaver somniferum L.)
opium(codein,thebaine,
papaverin)
reasonable
strychnos(Strychnos nux-vomica L.)
strychnine reasonable
hemlock fruit(Conium maculatum L.)
coniine reasonable
ipecacuanhae radix(Cephyaelis ipecacuanha Will.)
emetin,caphaelin
poor
Fatty oils and waxes
• Solubility isotherms of soybean oil
Stahl, E., Quirin, K.-W., Gerard, D.: Dense Gases for Extraction and Refining, Springer-Verlag, Berlin, 1988.
Effect of alcohol-entrainer on extraction rate
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140 160kg CO2 / kg dry corn germ
0 % alcohol
2.5 % alcohol
5 % alcohol
7.5 % alcohol
10 % alcohol
g oil / 100 g dry corn germ
List of raw materials for γ-linolenic acid
Raw material Yield CO2extraction
[%]
C18:3 in the extract(γ-linolenic acid)
[%]Oenothera biennis L. 22 8 - 12Borago officinalis L. 18 18 - 22Humulus lupulus L. 6 3 - 4Cannabis sativa L. 35 3 - 6Ribes rubrum L. 14 4 - 6Ribes negrum L. 18 16 - 19
Ribes grosullaria L. 15 10 – 12Rosa canina L. 12 24 - 31
Hippophae rhamnoides L. 12 26 - 30
Partition coefficient and selectivity of fish oil ethyl esters
Component K=y/x KA/K22
C16 0.090 7.5
C18 0.050 4.2
C20 0.027 2.3
C22 0.012 1.0
Two-column process for separation of EPA and DHA
Krukonis, V.J.: Processing with Supercritical Fluids in Charpentier, B.A., Sevemants, M.R. (Eds.): ACS Symposium Series 366, 26-43, ACS, Washington, 1988.
Extraction from lyophilised fermentation broths
Compound Micro-organism Methanol in CO2
1mevinolin Aspergilus terreus 3 %2chaetoglobosin Penicillium expansum 20 %2mycolutein unidentified 20 %2luteoreticulin unidentified 20 %2C16H12O7 Aspergillus fumigatus 0 %2sydowinin B Aspergillus fumigatus 20 %2elaiophylin Streptomyces sp. 20 %
1Larson and King, 19862Cocks et al., 1995
Partition coefficient of different compounds
Compounds K = y/x
N-alcohols C1 – C7 0.4…..31
Organic acids (wt basis) acetic acidbutyric acid
0.030.08
Esthersethyl formiateisoamyl acetate
16850
Continuous extraction broths
cells
cell separation unitCO2
productpressure reduction valve
fermenter
nutrients
extractor
Example: Extraction of pleuromutilin
Aqueous flow rate
ml/min
CO2 flowg/min
Ratio of CO2 to aqueous
w/v
Average extractor
residence timemin
Average extraction
%
1 10 10/1 130 78.4
2 10 5/1 65 65.0
1 20 20/1 130 88.8
2 20 10/1 65 76.9
Walford et al., 2000
Solubilization of proteins in supercritical fluids
H2O
H2O
CO2Head (hydrophilic)
Tail (CO2-philic)
*O
OO O
O
*n
m CF3 CF2 CF O CF2
CF3
COO-NH4+3
Flouorocarbons Hydrocarbon polymers
Modelling of SFE: Brunner’s equation
This image cannot currently be displayed.
)]exp(1[ ktYY EE −−= ∞
)]exp(1[)]exp(1[ 2211 tkYtkYY EEE −−+−−= ∞∞
•x concentration of soluble component(s) in solid phase (kg/kg )
•t time (s)
•K kinetic parameter (1/s)
•YE extraktion yield (kg/kg)
•YE∞ maximal extraction yield (kg/kg)
kxdt
dx −=
Fractionation of Greek sage oil
0 50 100 150 200 250 300 350 400 450 500
Idő (min)
0
1
2
3
4
5
6
Kih
ozat
al (
%)
összes 1. szeparátor 2. szeparátor
Parameters YE∞∞∞∞, % k, 1/min R
PE = 300 bar, TE = 45 °C 4,90 0,012 0,999
PSZ-1 = 90 bar, TSZ-1 = 30-40°C
YE1∞ = 2,30 k1 = 0,010 0,999
PSZ-2 = 20 bar, TSZ-1 = 20 °C YE2∞ = 2,59 k2 = 0,013 0,994
t (min)
Ytotal yield
2nd separator
1st separator
Component balances for solid and liquid phases
VyxJt
xVs d),(d)1( =
∂∂−− ερ VyxJ
h
yVu
t
yV ff d),(dd =
∂∂+
∂∂ ρερ
•x concentratin of soluble component(s) in solid phase (kg/kg)
•y concentation of soluble component(s) in supercritical fluid (kg/kg)
•J specific extraction rate (flux) (kg/(m3s))
•h length coordinate (at CO2 inlet h = 0) (m)
•t time (s)
•u fluid velocity (m/s)
ε voidage of packing (m3/m2)
ρf density of supercritical fluid (kg/m3)
ρs density of solid matrix (kg/m3)
Sovová’s model2The Sovová’s model describes the yield in function of the time using 3 equations:
τϑ t=
[ ])exp(10
Qx
Y−−= ϑ
Q
q<ϑ
)]1(exp[0
−−= kZQQ
q
x
Y ϑ kQ
q ϑϑ <≤
[ ]
−
−−+−= )1(exp1)exp(1ln
11
0
qSS
Sx
Yϑ kϑϑ ≥
kϑ
• Q, S dimensionless modelparameters [-]
• τ minimal extraction time [s]
• q soluble material fraction on the surface of the particles [kg/kg]
dimensionless time [-]
Zk, dimensionless length and time where and when the soluble material runs out from the surface [-]
[2] SOVOVÁ, H., Chemical Engineering Science, Vol. 49, 1994, p. 409
Parameters of the Sovová’s model
fm&
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•Solubility was estimated from an empirical equationor
from the initial slope of the extraction curves
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The initial concentration of soluble material wasestimated by traditional solvent Soxhlet-extraction
using n-hexane as solvent
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solidphase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The density of the carbon dioxide was calculated fromthe Bender equation of state at the pressure and
temperature of the extraction.
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of thefluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The density of the raw material was measured byHofsäss air pycnometer.
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The specific surface are was estimated from the surface-volume diameterof the particles, what was determined from sieve experiments using the
Rosin–Rammler–Bennett particle size distribution model.
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluidand the solidphase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The mass transfer coefficient in the fluid phase wasestimated from a Sherwood correlation.
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
Parameters of the Sovová’s model
•y* solubility at extraction pressure and temperature [kg/kg]xo initial concentration of soluble material [kg/kg] ρf, ρs density of the fluid and solid phase [kg/m3] ap specific surface area of the solid particles [m2/m3]
•kf, ks mass transfer coefficient in the fluid and the solid phase [m/s]
•ms amount of the raw material [kg]
• mass flow of the fluid [kg/s]
•ε void fraction in bed [m3/m3]
•The void fraction in bed was calculated from thedensity of the raw material and the bulk density.
∗=ym
xm
f
s
&
0τsf
fpfs
m
akmQ
ρερ)1( −
=&
∗−=
ym
xakmS
f
pss
)1(0
ε&
[ ]{ })exp(11ln1
SqSQ
qk −−+=ϑ
−
−+= 1exp
11ln
1Q
qS
qSZk ϑ
The experimental yield points and the calculated yield curves
•Extraction of marigold: pE=350 bar, TE= 40°C
0
1
2
3
4
5
6
7
0 100 200 300 400idő (min)
Y (%)
Kísérletileg meghatározott extrakciós hozamokEgyszerűsített modellel számított hozamSovová modellel számitott hozam
•time (min)
0
1
2
3
4
5
6
7
0 100 200 300 400idő (min)
Y (%)
Kísérletileg meghatározott extrakciós hozamokEgyszerűsített modellel számított hozamSovová modellel számitott hozam
•The experimental yield points
•time (min)
The experimental yield points and the calculated yield curves
•Extraction of marigold: pE=350 bar, TE= 40°C
0
1
2
3
4
5
6
7
0 100 200 300 400idő (min)
Y (%)
Kísérletileg meghatározott extrakciós hozamokEgyszerűsített modellel számított hozamSovová modellel számitott hozam
•time (min)
The experimental yield points and the calculated yield curves
•Extraction of marigold: pE=350 bar, TE= 40°C
0
5
10
15
20
25
0 200 400 600 800 1000idő (min)
Y (%)
11 kg/h,mért7 kg/h, mért4 kg/h, mért11 kg/h, számított7 kg/h, számított4 kg/h, számított
•Effect of the solvent flow rate on the extraction of corn germ, Sovová modell, pE=450 bar, TE=40°C
•time (min)
•11 kg/h, experimental
•7 kg/h, experimental
•4 kg/h, experimental
•11 kg/h, calculated
•7 kg/h, calculated
•4 kg/h, calculated
0.1
1
10
100
0 5 10
SFE SFI SFE/SFF PA
Invesment costs of high pressure units
I=A(V TW)0.25
VTW
Perrut, M.: Ind. Eng. Chem. Res., 39, 4531 (2000).
Production costs of SFE(NATEX, Austria)
Comparison of solvent extraction with SFE
Plant capacity
(t/year)
Production cost
(EUR/kg raw material)
Notes
SE SFE
300-400 3-8 4-10 medicinal plants,
cosmetics, spices
1000-1200 1-3.5 2-5 food additives,
specific vegetable
oils
10000-12000 0.5-1.2 0.75-1.2 coffee, hop
100000-120000 0.2-0.4 ? oilseeds
CONCLUSIONS
• There is a growing interest in new natural products that act very specifically without any side-effects.
• Supercritical fluid extraction is ideal for preparation of medicinal plant extracts.
• Carbon dioxide extracts are different from the traditional preparations not only in chemical composition, but in phytotherapeutical activity as well.
• There is an urgent need for more detailed phytochemical analysis of extracts.
CONCLUSIONS
• Commercial supercritical fluid processes have been still limited to few areas.
• Large capacity plants, with optimised design and operation lead to prices that are very often of the same order of magnitude as those related to classical processes.
• Moreover, there are also cases were supercritical fluids permit to make products or operations, that cannot be realised by any other methods.
Thank you for your kind attention!
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