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University of Aveiro
Chemisty Departament
Supervisors: Prof. João A. P. Coutinho and Dr. Mara G. Freire
Extraction of Added-Value Products from Biomass using Ionic Liquids
Ana Filipa M. Cláudio
Chemical Engineering Doctoral Program
Extraction
Quantification
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General Introduction
Extraction of Added-Value Products from Biomass using Ionic Liquids (ILs)
% w
t C
om
po
un
d 1
% wt Compound 2
Outline
Solid-Liquid Extraction from Biomass
Extraction using ABSand Caracterization
2
Chapter 1:
Conclusions
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Extraction of added-value compounds from raw materials
Valorization of sub-products or residues from biomass
Applications in the food, cosmetic and pharmaceutical industries
Precipitation
Distillation
Chromatography
Liquid-liquid extraction
The optimization of processes for the separation and purification of biomolecules aiming at finding cost-effective methods, able to provide high yields and high purity levels, and that are simultaneously more environmentally friendly and sustainable.
Conven
tional
Techniq
ues Expensive
Low yields
Toxic solvents
Disadvantages
Industry continually demands
General introduction – Extraction and Purification of Biomolecules
3
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Negligible vapour pressure;
Non-flammability;
High thermal and chemical stabilities;
High solvation ability for several compounds;
Liquid in a wide range of temperatures.
Salts with a melting point below 100 ºC
Characteristics
Properties
ILs
organic/ inorganic
anions
Constituted by :large organic
cations
Tunable properties by the selection of proper
cation/anion combinations.4
General introduction – Ionic Liquids (IL)
+
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Used to extract and separate a wide variety of biomolecules
Consist in two aqueous-rich phases containing polymer/polymer, polymer/salt or salt/salt combinations
Constituted by 70-90% of water
5
General introduction – Aqueous Biphasic Systems (ABS)
Do not use volatile organic compounds
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0
1
2
3
4
5
0.0 0.2 0.4 0.6 0.8
[C4m
im][
CF 3S
O3]
/ m
ol.k
g-1
[Salt] / mol. kg-1
K3PO4
K2HPO4/KH2PO4 , pH=7
KH2PO4
K2HPO4
pH ≈6 pH ≈ 9
Applicability:Optimization of the extraction conditions
IL - RICH PHASE
SALT - RICH PHASE
GALLIC ACID + H2O + IL + SALT
IONIC LIQUID
KH2PO4/K2HPO4
GAGA
GA
GA GA
IONIC LIQUID
K3PO4
GA
GA
GA
GA
GA
GA
GAGA
GA
IONIC LIQUID
Na2SO4
GA
GA GA
GA
GA GA
GA
GAGA
GA
GA
Acidic
medium
Neutral medium
Alkaline
medium
Scope
back-extraction and recyclability routes for IL-
based ABS
??
??
Binodal characterization
Different salts
and ILsDifferent
ABS
Different
pH
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
[IL]
/ (
mo
l.k
g-1
)
β parameter
[C4mim]Cl
[C4mim][CF3SO3]
[C4mim][N(CN)2]
[C4mim][CF3CO2] [C4mim]Br
[C4mim][CH3SO3]
[C4mim][CH3CO2]
β characterizes the IL
ability to form ABS
6
Extractions using ABS andtheir Characterization
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a)
% w
t C
om
po
un
d 1
% wt Compound 2
Biphasic region
Monophasic region
TComp2
BComp1
Tcomp1
X
Y
Z
BComp2
T
a) b)
Cloud point titration method
Salt
ILBiomol.
Biomol.
Biomol.K
Quantification
100W[Biomol.]W[Biomol.]
W[Biomol.]
SaltSaltILIL
ILIL
%EE
IL- rich phase
Salt - rich phase
ABS: Experimental Section
7
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0
2
4
0 1 2
[IL
] /
(mo
l∙k
g-1
)
[Na2SO4] / (mol∙kg-1)
Biphasic
Region
Monophasic
Region
8
2.1. Critical Assessment of the Formation of IL-Based ABS in Acidic Media
Na2SO4 + H2O H2O
IL
+
H2O
Cloud point titration method
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[C2mim][CH3SO4]
[C4mim]Cl
[C4mim][CH3CO2]
[C4mim][HSO4]
[C4mim][DMP]
[C6mim]Cl
[amim][C2H5SO4]
[C4mpip]Cl
[C4mpy]Cl
[C4mpyr]Cl
Do not promote ABS
[C2mim][CF3SO3] [C4mim][CF3SO3]
[C4mim]Br [C4mim][N(CN)2] [C4mim][CH3SO4] [C4mim][C2H5SO4]
[C4mim][TOS][C4mim][SCN]
[C4mim][CF3CO2][C4mim][OctylSO4]
[C7mim]Cl[C7H7mim]Cl
[C7H7mim][C2H5SO4] [C8py][N(CN)2]
Able to promote ABS
ILs with anions or cations with more hydrophobic characteristics have a greater capacity to promote ABS
2.1. Critical Assessment of the Formation of IL-Based ABS in Acidic Media
9
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Evaluation of the IL Anion Influence
[CF3SO3]- > □ [OctylSO4]
- > [TOS]- ≈ + [SCN]- > ▲ [N(CN)2]- > ○ [C2H5SO4]
- > ■ [CF3CO2]- ≈
[CH3SO4]- > Br- (>> Cl- that do not forms ABS with Na2SO4 aqueous solutions with [C4mim]+)
N+
N
X-
Ionic liquid β
[C4mim][PF6] 0.21
[C4mim][NTf2] 0.24
[C4mim][BF4] 0.38
[C4mim][CF3SO3] 0.46
[C4mim][N(CN)2] 0.60
[C4mim][CH3SO4] 0.67
[C4mim][SCN] 0.71
[C4mim][CF3CO2] 0.74
[C4mim][OctylSO4] 0.77
[C4mim]Br 0.87
[C4mim]Cl 0.95
[C4mim][DMP] 1.12
[C4mim][CH3CO2] 1.20
Hydrogen- bonding basicity
10Ab Rani et al., Phys. Chem. Chem. Phys., 2011, 13, 16831-16840; Lungwitz et al., New J. Chem., 2008, 32, 392-394.
▬
2.1. Critical Assessment of the Formation of IL-Based ABS in Acidic Media
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[C4mim][OctylSO4] > [C4mim][C2H5SO4] > [C4mim][CH3SO4]
[C4mim][CF3SO3] > [C2mim][CF3SO3]
Pyridinium cation >> imidazolium cation
[C7H7mim]+ > [C7mim]+ [C7H7mim]+ > [C4mim]+
Low Hydrogen Bond Basicity
11
2.1. Critical Assessment of the Formation of IL-Based ABS in Acidic Media at 25 ºC
Figure 2.1.4: Ternary phase diagrams for selected ionic liquids at 25
ºC and atmospheric pressure (evaluation of the cation/anion alkyl
chain length influence):▬, [C4mim][CF3SO3]; , [C2mim][CF3SO3]; ○,
[C4mim][C2H5SO4]; , [C4mim][CH3SO4], □, [C4mim] [OctylSO4].
0
2
4
6
8
0.0 0.5 1.0 1.5 2.0
[IL]
/ (
mo
l∙kg
-1)
[Na2SO4] / (mol∙kg-1)
Biphasic Region
MonophasicRegion
0
2
4
6
0.0 0.5 1.0 1.5 2.0
[IL]
/ (
mo
l∙kg-1
)
[Na2SO4] / (mol∙kg-1)
Biphasic Region
MonophasicRegion
Evaluation of the
Ions Alkyl Chain
Length
Evaluation of the
Cation Core
Figure 2.1.5: Ternary phase diagrams for selected ionic liquids at 25
ºC and atmospheric pressure (evaluation of the cation core and
functionalized groups influence): ▬, [C8py][N(CN)2]; ▲,
[C4mim][C2H5SO4]; , [C4mim][N(CN)2]; □, [C7H7mim][C2H5SO4]; ,
[C7H7mim]Cl; , [C7mim]Cl.
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0.0
1.0
2.0
3.0
4.0
5.0
0.0 0.2 0.4 0.6 0.8 1.0
[C4m
im][
CF
3S
O3]
/ m
ol. k
g-1
[Salt] / mol.kg-1
K2HPO4pH≈9
K2HPO4/KH2PO4
pH=7
KH2PO4
pH≈5
2.2. Evaluation of the Impact of Phosphate Salts on the Formation of IL-Based ABS at 25 ºC
Decrease of pH
12
K3PO4
pH≈13
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Ionic liquid β
[C4mim][CF3SO3] 0.4948
[C4mim][N(CN)2] 0.6048
[C4mim][CH3SO4] 0.6648
[C4mim][CH3SO3] 0.8550
[C4mim]Br 0.8750
[C4mim]Cl 0.9550
[C4mim][DMP] 1.1248
[C4mim][CH3CO2] 1.2048
Salts Ability of [C4mim]-based ILs for ABS formation
K3PO4
[C4mim][CF3SO3]18 > [C4mim][N(CN)2]18 > [C4mim][TOS] >
[C4mim][CF3CO2]18 > [C4mim][C2H5SO4] > [C4mim]Br18 ≈ [C4mim][CH3SO4] >
[C4mim][DMP] > [C4mim][CH3SO3]18 > [C4mim]Cl18 > [C4mim][CH3CO2]18
K2HPO4
[C4mim][CF3SO3] > [C4mim][TOS] ≈ [C4mim][N(CN)2] > [C4mim][C2H5SO4] >
[C4mim][CF3CO2] ≈ [C4mim][CH3SO4] ≈ [C4mim][DMP] > [C4mim]Br >
[C4mim][CH3CO2] ≈ [C4mim][CH3SO3] > [C4mim]Cl
K2HPO4/
KH2PO4
[C4mim][CF3SO3]43 > [C4mim][TOS]43 [C4mim][N(CN)2]43 > [C4mim][CF3CO2] >
[C4mim][C2H5SO4]43 ≈ [C4mim][DMP] ≈ [C4mim][CH3SO4] >
[C4mim][CH3CO2]43 ≈ [C4mim]Br > [C4mim]Cl43> [C4mim][CH3SO3]43
KH2PO4 [C4mim][CF3SO3]
pH
18. Ventura et al., J. Phys. Chem. B, 2009, 113, 9304-9310. 43. Ventura et al, J. Chem. Eng. Data, 2012, 57, 507-512. 48. Ab Rani et al., Phys. Chem. Chem. Phys., 2011, 13, 16831-16840. 50. Lungwitz et al., New J. Chem., 2008, 32, 392-394.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
[IL]
/ (
mo
l.k
g-1
)
β parameter
[C4mim]Cl
[C4mim][CF3SO3]
[C4mim][N(CN)2]
[C4mim][CF3CO2] [C4mim]Br
[C4mim][CH3SO3]
[C4mim][CH3CO2]
0
1
2
3
4
0.0 0.5 1.0 1.5
[IL]
/ (
mo
l.kg-1
)
β parameter
[C4mim][CF3CO2]
[C4mim][CF3SO3]
[C4mim][N(CN)2][C4mim][CH3SO3]
[C4mim]Br
[C4mim]Cl[C4mim][CH3CO2]
0
1
2
3
4
0.0 0.5 1.0 1.5
[IL]
/ (
mo
l.kg-1
)
β parameter
[C4mim][CF3SO3]
[C4mim][N(CN)2]
[C4mim][SCN]
[C4mim]Br
[C4mim]Cl
[C4mim][CH3CO2]
K3PO4K2HPO4
K2HPO4/KH2PO4
2.2. Evaluation of the Impact of Phosphate Salts on the Formation of IL-Based ABS at 25 ºC
13
13
9
7
5
pH Ability to form ABS
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Kamlet-Taft dyesThe β value is a numerical description of the hydrogen-bond
basicity of ILs and describes the importance of the individual
ability of each IL anion to accept hydrogen bonds.
This extended polarity scale of the ability of the IL anion to
hydrogen-bond can provide a priori information to select an
appropriate IL for a specific application before extensive and
time-consuming experiments.
2.3. Extended Scale for the Hydrogen-Bond Basicity of Ionic Liquids
14
The β parameter is widely used to support several IL features,
such as their solvation ability and phase behaviour.
Experimental
approach
Predictive model
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COSMO-RS is as a viable and expeditious tool to
estimate the hydrogen-bond basicity of ILs
Hydrogen-bonding interaction energy in the
equimolar cation-anion mixture obtained
from COSMO-RS
Hydrogen-bond acceptor ability of the IL anion.
Linear
Dependence
β = -0.0162 EHB (kJ.mol-1) + 0.3954R² = 0.7984
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-35 -25 -15 -5
β
EHB / (kJ.mol-1)
β = -0.0279 EHB (kJ.mol-1) + 0.0605R² = 0.9234
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-50 -40 -30 -20 -10 0
β
EHB / (kJ.mol-1)
a) b)
Lungwitz et al.Welton et al.
2.3. Extended Scale for the Hydrogen-Bond Basicity of Ionic Liquids
15
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0
1
2
3
4
5
0.0 0.2 0.4 0.6 0.8
[C4m
im][
CF 3S
O3]
/ m
ol.k
g-1
[Salt] / mol. kg-1
K3PO4
K2HPO4/KH2PO4 , pH=7
KH2PO4
K2HPO4
pH ≈6 pH ≈ 9
Applicability:Optimization of the extraction conditions for
added-value compounds
IL - RICH PHASE
SALT - RICH PHASE
GALLIC ACID + H2O + IL + SALT
IONIC LIQUID
KH2PO4/K2HPO4
GAGA
GA
GA GA
IONIC LIQUID
K3PO4
GA
GA
GA
GA
GA
GA
GAGA
GA
IONIC LIQUID
Na2SO4
GA
GA GA
GA
GA GA
GA
GAGA
GA
GA
Acidic
medium
Neutral medium
Alkaline
medium
back-extraction and recyclability routes for IL-
based ABS
??
??
Binodal caracterization
Different salts
and ILsDifferent
ABS
Different
pH
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5
[IL]
/ (
mo
l.k
g-1
)
β parameter
[C4mim]Cl
[C4mim][CF3SO3]
[C4mim][N(CN)2]
[C4mim][CF3CO2] [C4mim]Br
[C4mim][CH3SO3]
[C4mim][CH3CO2]
β caracterize IL behavior
16
Extractions using ABS andtheir Characterization
Initial investigations in order to evaluate the ability of IL and salts to promote ABS
Scope
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The IL anion has a higher impact on the extraction of L-tryptophan
Single-step extraction efficiencies
range between 72 % and 99 %.
17
2.4. Characterization of ABS Composed of IL and a Citrate-based Biodegradable Salt at 25ºC
71.85
95.25 97.02 96.19 96.85 96.93 98.62 99.06
0
20
40
60
80
100%EETrp
Extraction efficiencies in the order of 97-99 %
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2.5. Reversible pH-Triggered ABS
18
0
20
40
60
80
0 20 40 60
[C4m
im]C
l / (
wt
%)
[Salt] / (wt %)
Biphasic region
IL-rich phase
Salt- rich phase
Monophasic region
pH Ability to form ABS
Chapter 2.2
Why are these
systems
important?
Separation of
compounds
pH ≈6 pH ≈ 9
Fractionation of value-added
compounds present in a complex
mixture or in an extract from
biomass
-100
-80
-60
-40
-20
0
20
40
60
80
100
1 2 3 4
EE (
%)
Sudan III PB27
IL- rich phase
Salt -rich phase
[C4mim]Cl [C4C1mim]Cl [C4mpy]Cl [C4mpip]Cl
Complete separation
Proof of concept
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Effect of Salts in Gallic Acid Partitioning
Na2SO4 >> K2HPO4/KH2PO4 > K3PO4
The pH of the aqueous solution plays the major role in the
extraction of gallic acid
KGA decreases in the following order of inorganic salts:
2.6. Optimization of the Gallic Acid Extraction using Ionic Liquid-Based Aqueous Biphasic Systems
Most lead to
acidic aqueous solutionspH in system depends on the
IL used
pH = 7
Alkaline pH
Na2SO4
KH2PO4/
K2HPO4
K3PO4
0
10
20
30KGA
19
IL - RICH PHASE
SALT - RICH PHASE
GALLIC ACID + H2O + IL + SALT
IONIC LIQUID
KH2PO4/K2HPO4
GAGA
GA
GA GA
IONIC LIQUID
K3PO4
GA
GA
GA
GA
GA
GA
GAGA
GA
IONIC LIQUID
Na2SO4
GA
GA GA
GA
GA GA
GA
GAGA
GA
GA
Acidic
medium
Neutral medium
Alkaline
medium
pH > pKa uncharged molecule
pH < pKa charged molecule
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20
2.7. Development of Back-Extraction and Recyclability Routes for IL-based ABS
IL - RICH PHASE
SALT - RICH PHASE
GALLIC ACID + H2O + IL+ SALT IONIC LIQUID
SALT
GA
GA
GA
GA
GA
GA
GAGA
GA
IONIC LIQUID
SALT
GA
GA GA
GA
GA GA
GA
GAGA
GA
GA
Inorganic-salt - rich phase
[C4C1im][CF3SO3] - rich phase93.33
98.29
95.49
99.23-100
-80
-60
-40
-20
0
20
40
60
80
100System:25 wt% of [C4C1im][CF3SO3] + 20 wt% of Na2SO4
System:20 wt% of [C4C1im][CF3SO3] + 10 wt% of Na2CO3
%EE20
40
60
80
100
93.12
72.43
96.70
78.71-100
-80
-60
-40
-20
0
20
40
60
80
100
Inorganic-salt - rich phase
[C4C1im][N(CN)2] - rich phase
System:25 wt% of [C4C1im][N(CN)2] + 20 wt% of Na2SO4
System:20 wt% of [C4C1im][N(CN)2] + 10 wt% of Na2CO3
%EE
20
40
60
80
100
Extraction efficiency values of GA ranging between 93-99%;
Regeneration of 95% of the IL and further reutilization.
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General Introduction
Extraction of Added-Value Products from Biomass using Ionic Liquids (ILs)
% w
t C
om
po
un
d 1
% wt Compound 2
Solid-Liquid Extraction from Biomass
Extraction using ABSand Caracterization
21
Chapter 1:
Scope
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22
Scope
Guarana seeds
Spent coffee
Biomolecule recovery
Solid-Liquid Extractionfrom Biomass
High %EE
0
20
40
60
80
100
% E
E (w
t %
)
Ionic Liquids
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Motivation
23Valorization of spent coffee
It is a residue with almost no
commercial value.
The amount of caffeine ranges
from 3.59 to 8.09 mg/g.
Wh
y
Sp
en
t C
off
ee?
Guaraná seeds contain
about two to three more
caffeine than coffee beans,
and are a huge source of
biomass, especially found in
Brazil.
Wh
y
Gu
ara
ná?
Presents antibacterial and antifungal properties.
Inte
rest
on
Caff
ein
e
Natural pesticide
Caffeine could be used as an alternative repellent/toxicant for the control
of pest on food crops.
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Solid-Liquid Extraction: Experimental section
24
To extract caffeine from guaraná seeds and spent coffee using
aqueous solutions of ionic liquids (ILs)
Filtration
under
vacuum
biomass ofweight
extracted caffeineofweight caffeine
(wt%)
Extraction
Grinded biomass
+ aqueous
solutions of ILs
Quantification
ILs chemical structure
Extraction temperature - T
Extraction time - t
Solid-liquid ratio - R
Particles diameter - d
Concentration of IL - C
Operational conditions optimized:
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[C4mim]Cl [C2mim]Cl
[C4mim][TOS]
[C4mpyrr]Cl
[OHC2mim]Cl
[C2mim][CH3CO2]
Ionic Liquids studied
T = 70 ºC
RS/L = 1:10
Fixed parameters
C = 0.5 M
t = 30 min
% extracted caffeine is similar for all ILs
extracted caffeine Particles diameter
Results
[C4mim][TOS]
3.86
5.06
6.48
5.31 5.23 5.20 5.11
6.01
7.64
0
2
4
6
8
Caf
fein
e yi
eld
/ (
wt%
) d < 0.4 mm 0.4 < d < 1 mm
25
ILs are good solvents for the extraction of
caffeine
3.1. Enhanced Extraction of Caffeine from Guaraná Seeds using Aqueous Solutions of ILs
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Response surface
plots and contour
plots
Response surface methodology:
factorial planning 23 (T, R, t )
Constant
parameters
d= [0.4;1.0] mm
[C4mim]Cl =1 M
T vs R t vs R T vs t
T = [65 , 85] ˚C;
RS/L;
t = [30 , 50] min.
26
Resu
lts
Caffeine
extraction
3.1. Enhanced Extraction of Caffeine from Guaraná Seeds using Aqueous Solutions of ILs
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T = 70ºC
t = 30 min
Re
su
lts
R = 1:10
[C4mim]Cl = 2.34 M
d < 0.4mm
Response surface methodology:
Factorial planning 23 (T, R, C )
Constant
parameters
t = 30 min
d < 0.4 mm
T vs R C vs R C vs T
Optimized
point for the
caffeine
extraction
27
3.1. Enhanced Extraction of Caffeine from Guaraná Seeds using Aqueous Solutions of ILs
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Effect of butanol on
IL solutions?
21.93
0.09
13.75
20.99
18.92
1.92
16.89
7.24
17.68 17.69
0
5
10
15
20
25
[Caf
fein
e] /
(g.
L-1)
Recyclability
Improved re-extraction solvents:
Chloroform;
Methylene chloride.
Butanol can be a good candidate to re-extract caffeine .
The IL solutions do not lose their
extraction efficiency after the re-
extraction with butanol.substitute
Aim
R
es
ult
s
28
Selection of an organic solvent
(non-miscible with water) capable
of re-extracting caffeine from the IL
medium.Concentration of caffeine after the liquid-liquid extraction
Reusability (by cycles)
Res
ult
s
3.1. Enhanced Extraction of Caffeine from Guaraná Seeds using Aqueous Solutions of ILs
8.56
17.41
25.63
0
10
20
30
1st extraction 2nd extraction 3rd extraction
[Caf
fein
e]
(g.L
-1) 8.41
8.85
(……)
11 times
(94 g/L)
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3.2. Extraction of caffeine from spent coffee using
aqueous solutions of ILs
29
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3D Surf ace Plot of % caf ext against T(K) and R
Spreadsheet7 11v *20c
% caf ext = -6,9579+0,0372*x+6,7361*y -3,635E-5*x*x-0,0336*x*y +15,2727*y *y
> 1,6
< 1,55
< 1,45
< 1,35
< 1,25
< 1,15
< 1,05
< 0,95
< 0,85
310
320
330
340
350
360
370
T(K)
0,040,06
0,080,10
0,120,14
0 ,16
R
0,9
1,0
1,1
1,2
1,3
1,4
1,5
1,6
1,7
% caf ext
3D Contour Plot of % caf ext against T(K) and R
Spreadsheet7 11v*20c
% caf ext = Distance Weighted Least Squares
> 1,5
< 1,475
< 1,375
< 1,275
< 1,175
< 1,075
< 0,975
310 320 330 340 350 360 370
T(K)
0,04
0,06
0,08
0,10
0,12
0,14
0,16
R
3D Surf ace Plot of % caf ext against T(K) and t(min)
Spreadsheet7 11v *20c
% caf ext = -8,4016+0,0501*x-0,0368*y -6,5155E-5*x*x+0,0001*x*y -6,1331E-5*y *y
> 1,5
< 1,425
< 1,325
< 1,225
< 1,125
< 1,025
< 0,925
< 0,825
< 0,725
310
320
330
340
350
360
370
T(K)
0
10
20
30
40
50
60
t(min)
0,7
0,8
0,9
1,0
1,1
1,2
1,3
1,4
1,5
1,6
% caf ext
3D Surf ace Plot of % caf ext against R and t(min)
Spreadsheet7 11v *20c
% caf ext = 1,203-2,0108*x+0,0103*y +12,3536*x*x-0,0752*x*y -2,0457E-5*y *y
> 1,5
< 1,425
< 1,325
< 1,225
< 1,125
< 1,025
0,04
0,06
0,08
0,10
0,12
0,14
0,16
R
0
10
20
30
40
50
60
t(min)
1,0
1,1
1,2
1,3
1,4
1,5
1,6
% c
af e
xt
3.2. Extraction of caffeine from spent coffee using
aqueous solutions of ILs
Re
su
lts
Response surface methodology:
Factorial planning 23 (T, R, t )
Solvent: WATER
Response
surface and
contour plots
Caffeine
extraction
T = [80, 90] ˚C;
R;
t > 40 min.
R vs T t vs T t vs R Constants
parameters
d < 0.4 mm
30
http://path.web.ua.pt
1.752.15
3.57
2.43
1.39
0.0
1.0
2.0
3.0
4.0
5.0
[EA][Ac] [DEA][Ac] [TEA][Ac] [C4mim][Ac] H2O
% c
af (
w/w
)
OH
Ionic Liquids studied
T = 85 ºC
R = 1:10
Fixed parameters
C = 2.0 M
t = 45 min
Cations: Anions:
[C4mim]+
[Ac]-
> number of -OH groups
> amount of extracted caffeineResu
lts
31
3.2. Recovery of caffeine from spent coffee using
aqueous IL solutions
http://path.web.ua.pt
3.3. ILs as hydrotropes: A study on the enhanced solubility of biomolecules in water
32
0
50
100
150
200
250
0 5 10 15 20 25
[Vanillin] /
g.L-1
[IL] in water / wt %
11
Solubilityup to
18-fold
Only water
HO
HO
HO
O
OH
gallic acidO
N
N
NN
O
caffeine
HO
O
O
vanillin
23 ILs
6 conventional
salts
at different
concentrations
and temperature
IL display a
Hydrotrope role
Molecules that are constituted by a hydrophilic and a hydrophobic group, and thus, dramatically
increase the solubility of sparingly soluble organic compounds in water.
M.L.S. Batista, C.M.S.S. Neves, P.J. Carvalho, R. Gani and J.A.P. Coutinho, J. Phys. Chem. B, 2011, 115, 12879-12888.
http://path.web.ua.pt
3.3. ILs as hydrotropes: A study on the enhanced solubility of biomolecules in water
Increase of 40-fold regarding the
solubility of vanillin in a 1.5 M
[C4mim][TOS] aqueous solution
(compared to pure water)
A synergetic effect
of the two solvents
0
10
20
30
40
50
0 1 2 3 4 5 6
S/S0
Bio
mo
lecu
le
[IL]/ mol.L-1
Maximum
33
Effect of the IL concentration
Figure 3.3.3: Influence of the ILs concentration in the solubility of gallic acid in
aqueous solutions of , [C4C1im][N(CN)2] and , [C4C1im]Cl; and vanillin in
aqueous solutions of , [C2C1im][N(CN)2], ▲, [C4C1im][TOS], ×, [C4C1im]Cl,
caffeine in aqueous solutions of □, [C4C1im][N(CN)2] at 303 K. Lines have no
scientific meaning and are only guides for the eye.
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3.3. ILs as hydrotropes: A study on the enhanced solubility of biomolecules in water
HydrotropeKHyd (molbiomolecule.mol-1hydrotrope)
Vanillin Gallic acid Caffeine
[C2C1im]Cl 0.163 ± 0.006
[C4C1im]Cl 0.424 ± 0.014 0.556 ± 0.041 0.181 ± 0.002[C6C1im]Cl 0.866 ± 0.031[C8C1im]Cl 1.422 ± 0.042 0.6141 ± 0.013[C10C1im]Cl 1.127 ± 0.064[C12C1im]Cl 1.099 ± 0.038[C14C1im]Cl 0.997 ± 0.023[C4C1im]Br 0.311 ± 0.012 0.080 ± 0.002
[C4C1im][SCN] 0.376 ± 0.017 0.460 ± 0.016 0.465 ± 0.006[C4C1im][TOS] 1.164 ± 0.053 0.633 ± 0.048 0.463 ± 0.015
[C4C1im][CH3SO4] 0.438 ± 0.031 0.115 ± 0.014[C4C1im][CF3SO3] 0.414 ± 0.024 0.319 ± 0.034[C4C1im][N(CN)2] 0.656 ± 0.021 0.844 ± 0.049 0.541 ± 0.029[C2C1im][N(CN)2] 0.584 ± 0.039[C4C1py][N(CN)2] 1.284 ± 0.036* 1.533 ± 0.023 0.715 ± 0.031
[C4C1py]Cl 0.603 ± 0.058 0.612 ± 0.036 0.034 ± 0.003[C4C1pip]Cl 0.893 ± 0.037 0.501 ± 0.015 -0.021 ± 0.008[C4C1pyrr]Cl 0.420 ± 0.023 0.444 ± 0.042 -0.017 ± 0.003[N1112OH]Cl 0.129 ± 0.011 -0.049 ± 0.001
[N4444]Cl 1.077 ± 0.009 -0.107 ± 0.002 0.130 ± 0.004[P4444]Cl 0.879 ± 0.007* -0.103 ± 0.001 0.103 ± 0.002
[Na][SCN] 0.030 ± 0.002 -0.005 ± 0.001 0.374 ± 0.026Na[C7H5O2] 0.270 ± 0.003 0.083 ± 0.003 0.660 ± 0.056Na[C6H5O7] -0.059 ± 0.008 0.238 ± 0.004 -0.162 ± 0.003
NaCl -0.016 ± 0.002 -0.013 ± 0.002Na[TOS] 0.444 ± 0.034 0.218 ± 0.025
[N4444][TOS] 0.414 ± 0.065* 0.706 ± 0.096*[P4441][TOS] 1.029 ± 0.098* 0.932 ± 0.035*Na[N(CN)2] 0.325 ± 0.069 0.640 ± 0.049
A complex
phenomenon
occurs
Common salts do not increase the solubility of biomolecules
The capability of individual hydrotropes to improve the
solubility of each biomolecule is different
HydHyd0 KSS
The IL cation and
anion largely
influence the
solubility of
biomolecules in
water
1 M aqueous solutions of Ils may enhance the solubility of
the studied biomolecules up to 20-fold
*Form two-phases when IL aqueous solution have concentration above 10 wt % .
34
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
[Va
nil
lin
] /
mo
l.L-1
[hyd] / mol.L-1
Figure 3.3.4: Influence of ionic liquids concentration [hyd] in the vanillin solubility in water at
303 K: + [C2C1im]Cl, [C4C1im]Cl, [C6C1im]Cl, [C8C1im]Cl, ○ [C10C1im]Cl, + [C12C1im]Cl,
[C14C1im]Cl, [C2C1im][N(CN)2], [C4C1im][N(CN)2], [C4C1im][TOS], [C4C1im][SCN], □
[C4C1py]Cl, Na[C7H5O2], Na[SCN], ▬ Na[C6H5O7], NaCl, [N4444]Cl, Na[TOS],
[P4444]Cl, [N4441][TOS], [C4C1pyrr]Cl. Black dashed line is solubility in water ()
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Inherent Interest:
Important in the extraction and purification
of added-value products from a complex
mixture/solution.
The recovery of vanillin from the
hydrotrope solution can be attained by a
simple dilution with water
3.3. ILs as hydrotropes: A study on the enhanced solubility of biomolecules in water
Anti-solvent
35
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4. Conclusions
36
Compared with traditional extraction methods this new
strategy proved to be selective towards caffeine and
capable of providing high extraction yields. The
recovery and reusability of the ILs were successfully
demonstrated supporting the economic viability and low
environmental footprint of the proposed methodology.
Hydrotropy given by IL is of utmost important, since
molecules can be recovered from the solution by a
simple dilution with water
IL-based ABS are new approaches to perform
selective separations of added-value products and may
be further used for recycling or concentrating
hydrophilic ionic liquids from aqueous solutions.
Linear correlations between β vs EHB, providing an
extended polarity scale capable of characterizing the
IL anions’ abilities to hydrogen-bond when acting as
solvent media.
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Extend this type of extractions, followed by purification, to other high-value
products, for instance triterpenic compounds from Portuguese agroflorestry
biomass (residues of the cork, pulp and olive industries);
4. Future work
37
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Thank you for your attention!