development of a solubility parameters scale for ionic...

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Development of a Solubility

Parameters Scale for Ionic Liquids

Marta Batista

Orientado por:João A. P. Coutinho


Summary

Introduction

Biofuels

Ionic Liquids

Solubility Parameter

Estimation of the Solubility Parameter

Activity coefficients at infinite dilution

Viscosity

Experimental Section

Conclusion

Future work

Acknowlegdements


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


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


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


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


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)


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



Task - specific

Properties are related to the cation and anion that built the Ionic Liquid:

Hydrophobicity

Viscosity

Density

Structure – Property relations



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


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


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)


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


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


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


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



▸ 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∞


[C4MIM][PF6]




Collected data

0

1

2

3

4

5

6

7

15 20 25 30 35

γ∞


[C4MIM][BF4]

0

1

2

3

4

5

6

7

15 20 25 30 35

γ∞


[C4MIM][PF6]

47.929.62624.318.818.215.615.114.913.1

δ/ MPa1/2

Amphiphilic Characteristic of ILs




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




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]+




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




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




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




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



▸ 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



▸ 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]+



▸ 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



▸ 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


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]


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




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.



UV

IL in water and 1-propanol



Gravimetric Method

IL in toluene and 1-propanol


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


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


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.


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


Acknowlegdements

Professor João A.P Coutinho

Path group

development of a solubility parameters scale for ionic...

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