Post on 18-Nov-2019
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Development of a Solubility
Parameters Scale for Ionic Liquids
Marta Batista
Orientado por:João A. P. Coutinho
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Summary
Introduction
Biofuels
Ionic Liquids
Solubility Parameter
Estimation of the Solubility Parameter
Activity coefficients at infinite dilution
Viscosity
Experimental Section
Conclusion
Future work
Acknowlegdements
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Bioethanol & Biobutanol
Reneawable resources
Liquid transport fuels replacing the
usual fuels
Reduce emissions of hydrocarbon,
carbon monoxide
Improves the engine combustion
Introduction▸ Bioethanol and Biobutanol – Work context
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Introduction▸ Bioethanol and Biobutanol
The production of biofuels by fermentation requires a process for the
recovery of alcohol from the aqueous medium
DISTILLATION
The presence of water will form an azeotrope with the alcohol
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Azeotropic distillation
Liquid-liquid extraction
Pervaporation
Extractive distillation
Third component added to the mixture
– Change in the relative volatility of
compounds
- organic solvent- solid salt- mixture
-
Introduction▸ Extractive Distillation – Problem Resolution
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Introduction▸ Extractive Distillation with Ionic Liquids
IL as entrainer
Breaking of azeotropes
Less energy consumption
Lower costs
Lower capital investment
H.-J. Huang et al. / Separation and Purification Technology 62 (2008) 1–21
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Journal of Chemical & Engineering Data, Vol. 55, No. 4, 2010
Introduction▸ Extractive Distillation with Ionic Liquids
John Wiley, Biofuels, Bioprod. Bioref. 2:553–588 (2008)
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Introduction▸ Ionic Liquids
Molten salts, liquid at room
temperature
Bulky and Asymetric cation
Several types of anion
(halides, inorganic, organic)
Low melting point (<100ºC)
Non flammable
Negligible vapor pressure
Good thermal stability
Possibility of tune their properties for specific
task
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Introduction▸ Ionic Liquids
Task - specific
Properties are related to the cation and anion that built the Ionic Liquid:
Hydrophobicity
Viscosity
Density
Structure – Property relations
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Introduction▸ Ionic Liquids
Large number of potential ILs Unfeasibily to Study experimentaly
Normally used: Group contribution method
Predictive models
• Experimental Data• Theory
Ionic Liquid as entrainer
Extractive Distillation
Hildebrand solubility parameter
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1 Introduction▸ Solubility Parameter
Hildebrand
21
V
U
The Hildebrand theory was developed for
Regular Solutions:
• Systems with negligible excess volume and excess entropy
EE UG
Hildebrand and Scatchard equation for free Gibbs energy Relation with solubility parameter
2211
2
2121 VxVxUG EE
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1 Introduction▸ Solubility Parameter – estimation
i
vap
i
vap
iV
RTH
V
U
To estimate the solubility parameter they suggested that experimental data accordingto:
Maximum of solubility corresponds to the value of the overall solubility parameter for
the compound in study.
Or: using the mole fraction solubility
Peña M, Bustamante P, Chem Pharm. Bull. 48(2) 179-183 (2000)
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Introduction▸ Solubility Parameter
Bustamante.P, Chem & Pharm Bull, 1994. 42(5): p. 1129-1133
iif
CR
O
O H O
H O
C R
Chamaleonic effect
Defined by Hoy:
- Two different behaviours
accordingly to the solvents
present in the medium
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Introduction▸ Solubility Parameter
How does solubility parameter helps on the process of Extractive distillation?
j
iijS
Selectivity is an indicator of a promising solvent for one specific mixture
22ln jiijj VRT
Regular Solution Theory Selectivity
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Introduction▸ Solubility Parameters Scale – Aim of the project
Establishment of a solubility parameters scale
Estimation of solubility parameters:
Density
Viscosity
Surface tensions
Lattice energy
Melting points
Activity Coefficients at infinite dilution
Choise of the best IL
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i
ii
E xRTG )ln(
One of the most important thermodynamic properties is the activity coefficientwhich is related to the excess free Gibbs energy by,
Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution
Combining:
- previous equation with the one obtained by Hildebrand for GE with solubility parameter
-Applying infinite dilution conditions, Φi=1 and γi = γ∞
2ln jijVRT 2
1
ln
j
jiV
RT
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Collected data
Chameleonic Effectx
1
0
1
2
3
4
5
6
7
15 25 35
γ∞
δ solvente / MPa1/2
[C4MIM][BF4]
0
1
2
3
4
5
6
7
15 20 25 30 35
γ∞
δ solvente / MPa1/2
[C4MIM][PF6]
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Collected data
0
1
2
3
4
5
6
7
15 20 25 30 35
γ∞
δ solvente / MPa1/2
[C4MIM][BF4]
0
1
2
3
4
5
6
7
15 20 25 30 35
γ∞
δ solvente / MPa1/2
[C4MIM][PF6]
47.929.62624.318.818.215.615.114.913.1
δ/ MPa1/2
Amphiphilic Characteristic of ILs
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Estimation for two solubility parameters:
δ NP – NONPOLAR families;
δ P – POLAR families
Temperature 298.15K
Data for δj and Vj were collected from literature at 298.15 K
Data for γ∞ were collected from available data published at different temperatures
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
20.0
21.0
22.0
23.0
24.0
25.0
26.0
0 2 4 6 8 10
δN
P/
MP
a1
/2
n
NTF2
BF4
PF6
CF3SO3
SCN
[CnMIM]+
Alkyl chain length effect
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
36.0
0 2 4 6 8 10 12 14 16 18
δP/
MP
a1
/2
n
NTF2
BF4
PF6
SCN
CF3SO3
[CnMIM]+
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Cation family effect
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
IM py pyR
δN
P/
MP
a1
/2
CF3SO3
NTF2
BF4
[C4Cation]+
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
IM py pyR
δP
/ M
Pa
1/2
NTF2
BF4
CF3SO3
[C4Cation]+
H
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Anion effect
19
20
21
22
23
24
25
OcOSO3 NTf2 PF6 CF3SO3 BF4 SCN
δ N
P/ M
Pa
1/2
C4MIM
19
20
21
22
23
24
25
26
δN
P / M
Pa1/
2
C2MIM
19
20
21
22
23
24
NTf2 PF6 CF3SO3 BF4 SCN
δN
P/M
Pa
1/2
C6MIM
19
20
21
22
23
NTf2 PF6 BF4 Cl
δN
P/M
Pa
1/2
C8MIM
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Anion effect
19
21
23
25
27
29
31
33
35
SCN MeSO4 CF3SO3 BF4 NTf2 PF6
δP/M
Pa1
/2
C4MIM
19
21
23
25
27
29
31
33
35
EtSO4 SCN CF3SO3 TCB NTf2 FAP
δP/M
Pa1
/2
C2MIM
19
21
23
25
27
29
31
33
35
37
SCN NTf2 PF6
δP/M
Pa1
/2
C6MIM
19
21
23
25
27
29
31
33
35
BF4 NTf2 PF6
δ P/M
Pa1/
2C8MIM
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Estimation of Solubility Parameters
▸ Activity Coefficients at infinite dilution - Results & Discussion
Anion effect
23
24
25
26
27
28
29
30
31
CF3SO3 NTf2 BF4
δP/
MP
a1
/2
BMpy
BMpyR
21
21.5
22
22.5
23
23.5
24
NTf2 CF3SO3 BF4
δN
P/M
Pa
1/2
BMpy
BMpyR
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Estimation of Solubility Parameters
▸ Viscosity
viscositywith
molar energy of activation
A
vishN
VRTG 10 ln
Kilaru, P.K. and P. Scovazzo, Industrial & Engineering Chemistry Research,2008. 47(3): p. 910-919.
energy of vaporizationwith
molar free energy of activation
0
visv
vap GKE
2/1
1
9
1
1
101ln
A
v
hN
V
V
RTK
Solubility parameter for pure Ionic Liquid
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Estimation of Solubility Parameters
▸ Viscosity - Results & Discussion
Alkyl chain length effect Cation family effect
20.0
22.0
24.0
26.0
28.0
30.0
32.0
0 2 4 6 8 10
δ/ M
Pa
1/2
n
PF6
BF4
NTF2
[CnMIM]+
20.0
22.0
24.0
26.0
28.0
30.0
32.0
IM py pyR
δ/ M
Pa
1/2
BF4
NTF2
[C4Cation]+
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Estimation of Solubility Parameters
▸ Viscosity - Results & Discussion
Anion effect
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
33.0
δ/ M
Pa
1/2
C4MIM
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
NTF2 CF3SO3 BF4
δ/ M
Pa
1/2
C2MIM
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
33.0
NTF2 BF4 PF6 Cl
δ/ M
Pa
1/2
C6MIM
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
NTF2 PF6 BF4 Cl NO3
δ/ M
Pa1/
2
C8MIM
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Estimation of Solubility Parameters
▸ Viscosity vs Activity coefficient at infinite dilution
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
IM py pyR
δ/M
Pa
1/2
BF4_visc
BF4_NP
BF4_Polar
20.0
22.0
24.0
26.0
28.0
30.0
32.0
0 2 4 6 8 10
δ/ M
Pa
1/2
n
BF4_visc
BF4_Polar
BF4_NP
[CnMIM][BF4][C4X][BF4]
20.0
22.0
24.0
26.0
28.0
30.0
32.0
0 2 4 6 8 10
δ/ M
Pa
1/2
n
BF4_visc
BF4_Polar
BF4_NP
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
IM py pyR
δ/M
Pa
1/2
BF4_visc
BF4_NP
BF4_Polar
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2 Estimation of Solubility Parameters
▸ Viscosity vs Activity coefficient
20.0
22.0
24.0
26.0
28.0
30.0
32.0
34.0
NTf2 PF6 BF4 CF3SO3
δ/M
Pa
1/2
C4MIM_visc
C4MIM_NP
C4MIM_Polar
The values obtained for viscosity are closer to the solubility parameters for polar family
The behavior is similar to solubility parameters for nonpolar family
[C4MIM][X]
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The regular solution theory, proposed by Hildebrand has proved to be useful to predict phase behaviour of solutions without detailing molecular polarity or specificinteractions
Hansen
2222
hpdt
Each interaction is accounted
Estimation of Solubility Parameters
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Experimental Section
Ionic Liquid in study: [C4MIM][PF6]
Determination of the solubility of this IL at mixtures with different
compositions namely,15, 30, 45, 60, 75 and 90% of 1-propanol and
water, 1-propanol and toluene.
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Experimental Section
UV
IL in water and 1-propanol
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Experimental Section
Gravimetric Method
IL in toluene and 1-propanol
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Experimental Section Results and discussion
iif
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
15 17 19 21 23 25
xIL
/ w
t%
δ / MPa1/2
IL in toluene and 1-propanol1-propanol / vv% δ / MPa1/2 x IL / wt%
85 19.115 0.140
70 20.03 0.513
55 20.945 Miscible
40 21.86 Miscible
25 22.775 0.149
10 23.69 0.782
0 18.2 0.098
δNP= 22.34 MPa1/2, δ=29.98 MPa1/2
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Experimental Section Results and discussion
iif
1-propanol / vv% δ / MPa1/2 x IL / wt%
0 47.9 1.875
15 44.36 2.556
30 40.82 11.202
45 37.28 12.030
60 33.74 23.204
85 27.84 17.435
90 26.66 2.787
100 24.3 0.600
IL in water and 1-propanol
0
5
10
15
20
25
20 25 30 35 40 45 50
x IL/
wt%
δ / MPa1/2
δP=32.4 MPa1/2, δ=29.98 MPa1/2
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Conclusions
An amphiphilic (Chamaleonic) behavior of the ILs is observed when
solubility parameters are estimated from activity coefficients at infinite dilution;
The use of viscosity to estimate the solubility parameter shows that pure ILs act
predominantly as a polar molecules. Values for solubility parameters
equivalent to those obtained in presence of polar solvents are obtained;
Solubility measurements confirm the behavior observed with infinite dilution
activity coefficients;
It is shown that the Hildebrand solubility parameters (unidimensional) cannot
adequately describe the ILs behavior; The use of the Hansen’s approach is
suggested.
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Given the complexity of interactions, for future work it would be interesting to work in
the solubility parameters through Hansen’s theory which takes accounts three different
contributions,
2222
hpdt
Future Work
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Acknowlegdements
Professor João A.P Coutinho
Path group