Activity Coefficients at Infinite Dilution using the …...Activity Coefficients at Infinite...
Transcript of Activity Coefficients at Infinite Dilution using the …...Activity Coefficients at Infinite...
Activity Coefficients at Infinite DilutionActivity Coefficients at Infinite Dilutionusing the Dilutor Methodusing the Dilutor Method
Kyu-Jin Han, Jong-Hyeok Oh*, So-Jin Park†
Dept. of Chemical Engineering, Dept. of Chemical Engineering, Chungnam Chungnam National UniversityNational University* Korea Atomic Energy Research Institute* Korea Atomic Energy Research Institute
Introduction
Activity Coefficient (γ)
Definition : the ratio of Definition : the ratio of activityactivity to some convenient to some convenient measure of the measure of the concentrationconcentration in the liquid mixturein the liquid mixture
Important relation with Important relation with excess Gibbs energyexcess Gibbs energy
sii
i
ii
i
i
ii Px
Pyfxf
xa
==≡ 0γ
∑=i
iiE xRTg γln Binary
mixture 2211 lnln γγ xxRTg E
+=
Introduction
Activity Coefficient at Infinite dilution (γ∞)
Characterizing the behavior of a Characterizing the behavior of a single solute single solute
moleculemolecule completely surrounded by solventcompletely surrounded by solvent
A maximum nonA maximum non--ideality(excess property) : ideality(excess property) :
solutesolute--solvent interactionssolvent interactions in the absence of in the absence of
solutesolute--solute interactionssolute interactions
Prediction of the Prediction of the phase behavior of a mixturephase behavior of a mixture over over
the entire concentration rangethe entire concentration range
Separation factor in extractive distillation column : Separation factor in extractive distillation column :
used for the selection of selective solventsused for the selection of selective solvents
Introduction
Determination methods for γ∞
Indirect measurementIndirect measurement
Extrapolation of VLE data in whole or highly Extrapolation of VLE data in whole or highly
dilute composition regiondilute composition region
Dilutor methodDilutor method
Direct measurementDirect measurement
Differential Differential ebulliometryebulliometry methodmethod
Differential static techniqueDifferential static technique
In this work : In this work : Dilutor MethodDilutor Method
Based on the inert gas flow in the highly dilute Based on the inert gas flow in the highly dilute
solutionsolution
Possible to measure Possible to measure γγ∞∞ in solvent mixturesin solvent mixtures
Scope
Activity coefficients at infinite dilution for the solutes of Activity coefficients at infinite dilution for the solutes of nn--heptaneheptane
and benzene in the solvent of DMF and DMF/water mixtures(10 wt% and benzene in the solvent of DMF and DMF/water mixtures(10 wt%
of water) were measured with the help of the dilutor technique aof water) were measured with the help of the dilutor technique at the t the
temperature of 30, 40 and 50 temperature of 30, 40 and 50 °°C. C.
Activity coefficients at infinite dilution for methanol+Activity coefficients at infinite dilution for methanol+dimethyl dimethyl
cabonatecabonate(DMC), and the solutes of 1(DMC), and the solutes of 1--propanolpropanol and toluene in the and toluene in the
solvent of DMC were measured with the help of the dilutor technisolvent of DMC were measured with the help of the dilutor technique que
at the temperature of 20, 30, 40 and 50 at the temperature of 20, 30, 40 and 50 °°C.C.
The measured values for benzene in DMF were compared with the The measured values for benzene in DMF were compared with the
reference data, and all experimental data were compared with thereference data, and all experimental data were compared with the
estimated values using modified UNIFAC(Dortmund) at the same estimated values using modified UNIFAC(Dortmund) at the same
conditions.conditions.
Theory
Basic relation for the highly dilute componentBasic relation for the highly dilute component
Solute i :
Pure solvent :
PyPoyPx viii
si
siii ϕϕγ =
PyPoyPx vsssolvsolvsolvsolvsolvsolvsolv ϕϕγ =
At the condition of infinite dilution
( )
1
111
solv
solvsolv
solvsolv
≈
≈≈=
= ∞
v
si
ii
Poy
Poyx
ϕϕ
γγγ
PyP
PyPxs
is
isiii
solvsolv =
=∞ϕγ
TheoryCalculation of Calculation of γγ∞∞ in Dilutor methodin Dilutor method
( )t
AAa i 0/ln=Slope of decrease of solute :
From the material balance in the cells and thermodynamic relations
( )RTF
RTnVP
n
Pt
AAs
isii
si
siii in
solv
gsolv
0
1
/ln &
+
−=∞
∞
ϕγϕγ
( )
+
+−=∞
gsolvHe
solv
/1 Va
PPFP
RTns
si
si
i &ϕ
γ
Experiment
Figure. Picture of the dilutor system for measuring γ∞.
Experiment
Figure. Schematic diagram of the dilutor system.
A : carrier gas
B : elec. flowmeter
C : heating coil
D : saturation cell
E : equilibrium cell
F : septum
G : stirring motor
H : transfer line
I : sampling valve
J : GC
K : PC
L : bubble flowmeter
TH1, TH2 : thermostats
DMF (C3H7NO)
A : 7.10850
B : 1537.78
C : 210.390
Antoine Constants
0.9440 g/cm3Density (25 oC)
153 oCNormal Boiling Point
73.10 g/molMolecular Weight
Experiment
DMC (C3H6O3)
A : 7.09722
B : 1285.21
C : 214.536
Antoine Constants
1.0694 g/cm3Density (20 oC)
90.3 oCNormal Boiling Point
98.08 g/molMolecular Weight
Experiment
CH3H3CO O
C
O
Figure. Comparison of the experimental γ∞ values with the reference data* for n-heptane in DMF at various temperatures.
[* Popescu, R. et al., Rev.Roum.Chim., 18, 746 (1967)]
Results
1000/T
2.9 3.0 3.1 3.2 3.3 3.4
2.1
2.4
2.7
3.0
3.3
experimental datareference data*modified UNIFAC(Dortmund)
y=1.2365x-1.0503r2=0.9999
1000/T
2.9 3.0 3.1 3.2 3.3 3.4
2.1
2.4
2.7
3.0
3.3
experimental datareference data*modified UNIFAC(Dortmund)
y=1.2365x-1.0503r2=0.9999
∞γln∞γln
Figure. Activity coefficients at infinite dilution for benzene as a function of temperature in DMF.
Results
1000/T
3.0 3.1 3.2 3.3 3.40.0
0.2
0.4
0.6
0.8
experimental datamodified UNIFAC(Dortmund)modified UNIFAC(Dortmund-Unpublished)
y=0.1473x+0.0199r2=0.9893
1000/T
3.0 3.1 3.2 3.3 3.40.0
0.2
0.4
0.6
0.8
experimental datamodified UNIFAC(Dortmund)modified UNIFAC(Dortmund-Unpublished)
y=0.1473x+0.0199r2=0.9893
∞γln∞γln
Figure. Activity coefficients at infinite dilution for n-heptane as a function of temperature in the solvent mixture DMF/water(10wt%).
Results
∞γln∞γln
1000/T
3.0 3.1 3.2 3.3 3.43.0
3.5
4.0
4.5
5.0
experimental datamodified UNIFAC(Dortmund)
y=1.5227x-0.4592r2=0.9651
1000/T
3.0 3.1 3.2 3.3 3.43.0
3.5
4.0
4.5
5.0
experimental datamodified UNIFAC(Dortmund)
y=1.5227x-0.4592r2=0.9651
Results
∞γln∞γln
Figure. Activity coefficients at infinite dilution for benzene as a function of temperature in the solvent mixture DMF/water(10wt%).
1000/T
3.0 3.1 3.2 3.3 3.40.6
0.9
1.2
1.5
1.8
experimental datamodified UNIFAC(Dortmund)
y=0.3935x+0.0996r2=0.9990
1000/T
3.0 3.1 3.2 3.3 3.40.6
0.9
1.2
1.5
1.8
experimental datamodified UNIFAC(Dortmund)
y=0.3935x+0.0996r2=0.9990
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.350.6
0.9
1.2
1.5
1.8
2.1
experimental datamodified UNIFAC(Dortmund)
y = 0.9989x + 1.839r2 = 0.9994
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.350.6
0.9
1.2
1.5
1.8
2.1
experimental datamodified UNIFAC(Dortmund)
y = 0.9989x + 1.839r2 = 0.9994
∞γln∞γln
Figure. Activity coefficients at infinite dilution for methanol as a function of temperature in DMC.
Results
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35
1.6
1.8
2.0
2.2
2.4y = -1.2997x + 6.2507r2 = 0.9959
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35
1.6
1.8
2.0
2.2
2.4y = -1.2997x + 6.2507r2 = 0.9959
∞γln∞γln
Figure. Activity coefficients at infinite dilution for DMC as a function of temperature in methanol.
Results
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45
2.0
2.2
2.4
2.6
2.8
y = 1.1537x -1.5089r2 = 0.9025
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45
2.0
2.2
2.4
2.6
2.8
y = 1.1537x -1.5089r2 = 0.9025
∞γln∞γln
Figure. Activity coefficients at infinite dilution for 1-propanol as a function of temperature in DMC.
Results
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45
0.4
0.6
0.8
1.0
1.2y = 0.8615x -2.0186r2 = 0.9965
1000/T
3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45
0.4
0.6
0.8
1.0
1.2y = 0.8615x -2.0186r2 = 0.9965
∞γln∞γln
Figure. Activity coefficients at infinite dilution for toluene as a function of temperature in DMC.
Results
Conclusions
Activity coefficients at infinite dilution for the solutes of Activity coefficients at infinite dilution for the solutes of nn--heptaneheptane
and benzene in the solvent of DMF and DMF/water mixtures(10 wt% and benzene in the solvent of DMF and DMF/water mixtures(10 wt%
of water) were determined experimentally using the dilutor methoof water) were determined experimentally using the dilutor method d
at various temperatures. And the at various temperatures. And the γγ∞∞ data were measured for the data were measured for the
system of methanol+DMC and the solutes of 1system of methanol+DMC and the solutes of 1--propanolpropanol and and
toluene in the solvent of DMC at the same conditionstoluene in the solvent of DMC at the same conditions
The experimental results show good agreements with the referenceThe experimental results show good agreements with the reference
data and the calculated values using modified UNIFAC(Dortmund).data and the calculated values using modified UNIFAC(Dortmund).
The dilutor method is excellently suitable for the measurement oThe dilutor method is excellently suitable for the measurement of f
activity coefficients at infinite dilution not only in pure solvactivity coefficients at infinite dilution not only in pure solvent but ent but
also in solvent mixture.also in solvent mixture.