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Extraction and separation of valuable materials of plant origin
Edit Székely, Erika Vági
BME, Department of Chemical and Environmental Process Engineering
Environmentally benign chemical
processes (EBChemP)
Traditional extraction (solvent/water) or
supercritical CO2 extraction
Main component families in plants
Oils and
waxes(waxes, oils,
phospholipids,
fatty acids,
tocopherols,
fitosterols, linear
chain alkanes)
Pigments(carotenoids,
chlorophylls,
xanthophyll,
anthocyanids) Alkaloids(proto-, pseudo-
alkaloids)
Miscellaneous(Diterpenes,
triterpenoids,
flavonoids,
cumarins,
glycosides, peptides
etc)
Volatile oils(monoterpenes,
sesquiterpenes,
sulphur compounds
etc.)
Volatile aromas
Steam distillation
Medieval representation
Steam distillation (past)
Methods to obtain volatile oils
Water, water and steam or steam distillation
Hydrodiffusion/ percolation
Cold pressing
Solvent extraction
- Concrete
- Absolute
- Enfleurage
Boiling points of typical volatile oil
components
Monoterpene hydrocarbons: 160-180°C
Monoterpene alcohols: 200-230°C
Sesquiterpene hydrocarbons: 260-290°C
α-humulene
Theoretical background
PPP wateroil 00
P
Py oil
oil
0
P
Py water
water
0
0
0
oil
water
oil
water
p
p
n
n
oiloil
waterwater
oil
water
Mp
Mp
m
m
0
0
Calculated water requirement
Monoterpene hydrocarbons 0.6 kg/kg
Monoterpenes containing oxygen 8 kg/kg
Sesquiterpenes 18 kg/kg
In practice more is needed (min. 10 kg/kg):
– Non-equilibrium
– Volatile oil is dissolved in waxes
– Volatile oil is in the cells
Water, water and steam or steam
distillation
water
water
and plant
steam
Sieve plateSieve plate
water
water
and plant
Sieve plate
Perforated tubesteam
plant
to condenser to condenser
to condenser
condense H2Ocondense H2O
Steam
distillation –
industrial
size
Methods to obtain volatile oils
Water, water and steam or steam distillation
Hydrodiffusion/ percolation
Hydrodiffusion
Essential oil separation - Florentine
flask• The final step in the distillation of essential oils is the separation from the
water flowing from the condenser using a special flask called a Florentine.
• Most essential oils are lighter than water and float to the surface of the
Florentine.
• Some oils, however, are denser than water and sink to the bottom. For this
reason two types of Florentine are used.
Methods to obtain volatile oils
Water, water and steam or steam distillation
Hydrodiffusion/ percolation
Cold pressing
Rolling Mill
Rolling Mill
Flaking Mill
Flaking Mill
It is employed in the oilseed
processing industry for the flaking of
cracked soy beans and soft oil seeds
such as sunflower, canola and corn
germ.
Proper oilseed flaking is a critical
factor in the oil extraction process, as
the seed's microscopic oil cells are
ruptured, allowing the extraction media
to penetrate easier into the material.
Cold pressing of olive oil
Screw press
Screw press
Methods to obtain volatile oils
Water, water and steam or steam distillation
Hydrodiffusion/ percolation
Cold pressing
Solvent extraction
- Concrete (with apolar solvent)
- Absolute (with ethanol)
- Enfleurage (with fat)
Characterization of solvent
Polarity ~ solvent power ~ solubility parameter
().
= [(ΔHV – RT)/ V]^0.5
ΔHV – latent heat at T temperature (J/mole);
V – molar volume (m3)
Choosing a solvent
For apolaric compounds:
→ Oils, fatty acids;
→ Essential oils;
→ Sterols (phytosterols);
→ Triterpenes;
→ Carotenoids.
Petrol ether,
pentane,
hexane,
Cyclohexane,
scCO2
etc…..
=
14.9
16.2
For polaric compounds:
→ Glycosides (saponins);
→ Alkaloids;
→ Gallic- and ellagic tannins;
→ Acids, sugars;
→ Bitter compounds.
Water,
EtOH:water
mixture
= 30 - 48
Choosing a solvent
For semi-polaric compounds:
→ Alkaloids;
→ Terpene-lactones;
→ Gylcoside-aglycons
(flavons, antrakinons,
anthocyanids);
→ Flavonoids;
→ Catechins,
pro-anthocyanids.
ether,
Ethyl-acetate,
Ethyl-alcohol,
methanol
acetone,
etc….
=
18.2
26.1
29.7
Choosing a solvent
Main steps of solid-liquid extraction
Extraction of oily seeds 100-200 tonnes / day in continuous operations.
Solvent extraction
Clean solvent
Pre-treatment Extraction Solvent
recovery
Extracted
material
Solvent
separation
Raw material
Regenerated solvent
Raffinate
Solvent extraction plant
Solvent extraction plant
Solid-liquid extractor
De Smet extractor
Linear wall extractor
Lurgi extractor
Lurgi extractor
Crown extractor, model IIRaw material
Solvent
Extracted
residue
Extract
Crown extractor, model II
Crown extractor, model II
Karussel- (Rotocel-) extractor
Karussel- (Rotocel-) extractor
CONTEX-extractor
Recovery of solvent from miscella
Deodorization / Oil refining
Krupp-toaster
Paddle dryer
Paddle dryer
Hexane content
Substitution of hexane
• Reasons: environmental and health; but:
economical at large scales or producing high
value products (e.g. sesame oil, rosehip oil)
• Possible alternative processes:
– Supercritical fluid extraction
– Water based extraction after cell disruption by
enzymatic treatment
– Cell disruption by ultrasound
– Osmotic shock
Emission decrease
• Condensation and scrubbers
• Recycling the solvent within the plant
• Technological improvements (leakage detection,
maintenance)
• Management issues (e.g. following the route of the
solvent)
Acknowledgement for Prof. Edit Székely and Prof.
Béla Simándi for using these slides, photos.
Thank you for your attention!
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