1. Research Scholar: Prasad V. Vernekar
Research Supervisor: Dr. A. W.
Patwardhan
21st
September
2013

2. Motivation
 Separation of minor actinides from simulated
high level waste (SHLW) using Hollow fiber
supported liquid membrane (HFSLM) and Non-
dispersive solvent extraction (NDSX)
 Metal ion separations using HFSLM
 Scale up for industrial applications
 Various parameters affect the metal ion
permeation across the membranes
 Need for a Mathematical model to represent
transport mechanism in membranes
2

3. Objective
 Separation of metal ions/actinides using:
 Hollow fiber supported liquid membrane
(HFSLM) process
 Non-dispersive solvent extraction (NDSX) process
 Modeling and simulation of HFSLM process
 Extend the model to represent NDSX process
 The model should be able to estimate
separation efficiencies for different process
3

4. Overview
 What is Hollow fiber supported liquid
membrane (HFSLM) ?
 Study of different systems (5 cases)
 Experimental set up
 Transport mechanism
 Model Development
 Model Validation against experimental data
 Conclusions
4

5. What is HFSLM?
Carrier fluid
(extractant)
5

6. HFSLM Specifications
6
HFSLM module Liqui-Cel® X50 (2.5"x8")
Fiber type Polypropylene X50 fibers
Number of fibers (N) 9950
Fiber internal radius (ri), μm 120
Fiber outer radius (ro), μm 150
Effective module outer diameter (da),
cm
4.67
Effective module inner diameter (di),
cm
2.2
Effective pore size (rp), μm 0.03
Porosity (ε), % 40
Tortuosity (τ) 2.5
Effective fiber length (L), cm 15

7. Extraction of Nd3+ ions from aqueous
nitrate media using N,N,N’,N’-tetraoctyl
diglycolamide (TODGA) using HFSLM
CASE 17

8. System details
8
 Process  HFSLM
 Feed phase  Nd(NO3)3 in nitric acid media
 Extractant  N,N,N’,N’-tetraoctyl diglycolamide
(TODGA)
 Phase modifier  N,N-dihexyl octanamide
(DHOA)
 Diluent  n-dodecane

9. Complexation reactions
3
),(
3
)(3
)(
3
)(33
3
),(
3
)(3)(
3
)(33
][][
][
]3)([
tcoefficienonDistributi
][][][
]3)([
constantExtraction
freeorgaq
d
ex
aq
org
d
freeorgaqaq
org
ex
TODGANO
K
K
Nd
TODGANONd
K
TODGANONd
TODGANONd
K








Neodymium
Transport
Acid Transport
9
Nd3+
(aq) + 3NO3
-
(aq) + 3TODGA(org) Nd(NO3)3 ·3TODGA(org)
H+
(aq) + NO3
-
(aq) + TODGA(org) TODGA·HNO3(org)
(Source: Ansari et al., Ind. Eng. Chem. Res. 2009, 48, 8605–8612)
Kex
KH

10. Cf0
t
Feed
concentration
Experimental set-up
10
side...Strip)(
side...Feed)(
0
0
0
0
ssZs
s
s
ffZf
f
f
CCQ
dt
dC
V
CCQ
dt
dC
V


Cf0
CfZ
Cs0
CsZ
Qf
Qs
Cs0
t
Strip
concentration

11. Transport Mechanism
Membrane
phase
Source
phase
Receiver
phase
Feed
side
film
Strip
side
film
Cf
Cif
Cimf
Cims
Cis = Cs
Carrier: TODGA
Diluent: n-
dodecane
11

12. Danesi’s permeability based
model
Danesi’s equation for HFSLM
process
12
t
V
AP
C
Ct
1
ln
0 










NPLr
Q
i
T

 LNrA i2
Where,
A = Total effective surface area of hollow
fiber
P = Permeability coefficient
V = Total volume of the feed solution
N = Total number of fibers
Ф = Parameter of module
QT = Volumetric flow rate
y = 7.497E-02x
0 20 40 60 80
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Time (min)
ln[C0/Ct]
Assumption: Concentration of the complex species on the strip-side is zero
3.5M HNO3
(Source: Danesi, P. R., Journal of Membrane Science 1984, 20,

13. Danesi’s permeability based
model
2M HNO3
13
y = 5.887E-02x
0 20 40 60 80
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Time (min)
ln[C0/Ct]
y = 7.254E-03x
0 50 100 150 200
0
0.2
0.4
0.6
0.8
1
1.2
Time (min)
ln[C0/Ct]
1M HNO3
Feed phase : 1g/l Nd3+ in aqueous nitrate medium
Organic phase : 0.1M TODGA diluted with n-dodecane + 0.5M DHOA (phase
modifier)

14. Membrane diffusivity
14
so
i
mlm
i
f kr
r
Pr
r
kP

11
3
,
3
3
3
,
3
3
3
)(33
][][][][][
]3)([
orgfree
d
orgfree
org
ex
TODGANO
K
TODGANONd
TODGANONd
K




 
Where,
Pm = Membrane permeability = Kdkm
km = Membrane mass transfer coefficient
Assumption: Strip-side resistance is negligible
3
,
3
3 ][][
11
orgfreeexmlm
i
f TODGANOKkr
r
kP 
 
y = 16.014x + 39.958
0 20 40 60 80
0
200
400
600
800
1000
1200
1400
Kex[NO3]3[TODGA]3
1/P
m
mem
m
t
D
k 
Estimated values:
kf = 4.2 x 10-6 m/s
Dmem = 7.0 x 10-
10 m2/s

15. Assumptions
 Fluid is Newtonian and isotropic
 Isothermal operation
 Fully developed laminar flow condition
 The overall mass transfer coefficient (K) is
constant over the length of hollow fiber module
 Mass transfer is modeled by Film Theory
 The Complexation/De-complexation reactions
are instantaneous
 The strip-side film offers negligible resistance
15

16. Equilibrium-based approach
……..……...Bulk of feed phase to the feed-membrane interface
....Feed-membrane interface to the strip-membrane
interface
………….…Strip-membrane interface to the bulk of strip phase
tcoefficientransfermassOverall
][][
][][
,
1
2
3
),(,
3
32
3
),(,
3
31






K
k
km
TODGANOK
C
C
k
TODGANOK
C
C
k
where
freeorgssex
is
ims
freeorgffex
if
imf
With steady state assumption we have,
Rate of mass transfer of metal ions (RT)
)(
)(
)(
sissT
imsimf
o
m
TCMT
ifffT
CCkR
CC
d
D
RR
CCkR



K
C
k
k
C
k
k
kkD
d
k
C
k
k
C
R
sf
sm
o
f
sf
T
1111
1
2
1
2
1
1
2



























)( sfT mCCKR 
16

17. Feed-side mass transfer coefficient
(kf)
3
1
2
3
1
64.1
64.1










LD
ud
D
kd
PeSh
fifi
Where,
di = Internal diameter (of fiber) = 2rif
uf = Velocity (of fluid in fiber)
L = Length (of hollow fiber module)
D = Diffusivity (of metal ion)
Leveque equation
17
(Source: Yang and Cussler, AIChE Journal, 1986, 32(11): 1910-1916)

18. Metal ion diffusivity
6.0
5.018
)(103.117
A
B
AB
v
TM
D




Where,
DAB = Diffusivity of solute ‘A’ through solvent ‘B’ (m2/s)
φ = Association factor for solvent
MB = Molecular weight of solvent ‘B’ (kg/kmol)
T = Temperature (K)
μ = Viscosity of solution (kg/(m.s))
vA = Solute molal volume at normal boiling point (m3/kmol)
Wilke-Chang Equation
18
(Source: Wilke and Chang (1955) AIChE Journal, 1(2): 264-270)

19. Strip-side mass transfer coefficient
(ks)
6.033.0
33.0
93.0
47.033.0
8.03
1
83.03
1
6.03
1
Re022.0
Re25.1
Re8.0
Re206.0
Re38.0
Re1.12
ScSh
Sc
L
d
Sh
ScSh
ScSh
ScSh
ScSh
e












Where,
de = Equivalent diameter (for shell-side
fluid)
us = Velocity (of fluid in shell)




se
es
ud
D
Sc
D
dk
Sh



Re
Correlations available in literature
19
… (Wakao & Kaquei,
1982)… (Tan et al, 2003)
… (Puigenne et al, 1997)
… (Pierre et al, 2001)
… (Yang & Cussler, 1986)
… (Knudsen & Katz, 1958)

20. Model Equations
Material balance across fiber at any location
(z) dzrNRdCQ ifTff   2
dz
ur
K
dC
mCC
dzmCCKdCur
fif
f
sf
sfffif


2
)(
1
2)(



Where,
ε = Porosity of hollow fiber module
N = Total number of fibers
Integrating over the module length we have,
 

dz
ur
K
dC
mCC fif
f
sf
2
)(
1
fiff urNQ
2
 
Therefore,
20
z + dz
Z
Fiber
Length
Feed
In
(Cf0)
Strip
out
(CsZ)
Feed out
(CfZ)
Strip in
(Cs0)
Direction of
Mass transfer
SLM
z

21. Model Equations (cont..)




























































s
f
fifs
f
s
f
fif
s
s
f
fifs
f
f
fZ
Q
Q
m
ur
KZ
Q
Q
m
Q
Q
m
ur
KZ
mC
Q
Q
m
ur
KZ
Q
Q
mC
C
1
2
exp1
1
2
exp11
2
exp1 00


Module exit concentrations for Nd3+ ions:
)( 00 fZf
s
f
ssZ CC
Q
Q
CC 
For feed phase…
For strip phase…
21

22. Model Equations (cont..)




























































s
f
h
fif
h
s
f
h
s
f
h
fif
h
hsh
s
f
h
fif
h
s
f
hhf
hfZ
Q
Q
m
ur
ZK
Q
Q
m
Q
Q
m
ur
ZK
Cm
Q
Q
m
ur
ZK
Q
Q
mC
C
1
2
exp1
1
2
exp11
2
exp1 00


Module exit concentrations for H+ ions:
)( 00 hfZhf
s
f
hshsZ CC
Q
Q
CC 
For feed phase…
For strip phase…
22
sideStrip...)(
sideFeed...)(
0
0
0
0
hshsZs
hs
s
hfhfZf
hf
f
CCQ
dt
dC
V
CCQ
dt
dC
V


Mass balance across reservoir for H+ ions

23. Problem Statement
3
0
3
3
0
3
0
3
3
)3(][
)()(
)3(][
imffif
imf
ex
imsimf
m
ifffT
imsss
ims
ex
CLNOC
C
K
CC
d
D
CCkR
CLNOC
C
K







)(][
)()(
)(][
03
0
03
himffhif
himf
H
himshimf
hm
hifhffhT
himsshs
hims
H
CLNOC
C
K
CC
d
D
CCkR
CLNOC
C
K







6 EQUATIONS
6 UNKNOWNS
Cif, Cimf, Cims
Chif, Chimf, Chims
H+
(aq) + NO3
-
(aq) + TODGA(org) TODGA·HNO3(org)
23
Nd3+
(aq) + 3NO3
-
(aq) + 3TODGA(org) Nd(NO3)3 ·3TODGA(org)
Gujar R.B. et al. (2009) Proceedings of the Nuclear and Radiochemistry Symposium, NUCAR-2009,
January 7-10, 2009
Kex =
1000
KH = 4.1
Ansari S.A. et al. (2005) Solvent Extraction and Ion Exchange, 23: 463–479
Kex
KH

24. Base case
24
Dm = 6.0 x 10-12 m2/s (Nd-TODGA
complex)
-10 2
Experimental conditions:
• Feed phase: 0.56 g/l Nd3+ at 3 M HNO3 (500 ml)
• Carrier: 0.1M TODGA + 0.5M DHOA in n-dodecane
• Strip phase: Distilled water (500 ml)
• Feed / strip phase flow rates: 200 ml/min
0
1
2
3
4
0 10 20 30 40 50 60 70
HNO3concentrationinfeedreservoir(M)
Time (min)
Experimental
Prediction
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+ionsLeftinthefeedreservoir
Time (min)
Experimental
Prediction
kf = 1.68 x 10-5 m/s
ks = 7.25 x 10-5 m/s

25. 0
20
40
60
80
100
0 30 60 90 120 150 180 210
%Nd3+
ionsLeftinfeedReservoir
Time (min)
Effect of feed phase acidity
25
0
20
40
60
80
100
0 30 60 90 120 150 180 210
%Nd3+ionLeftinfeedReservoir
Time (min)
0.5MHNO3-Exp 0.5MHNO3-Pred
2MHNO3-Exp 2MHNO3-Pred
3.5MHNO3-Exp 3.5MHNO3-Pred
0.01
0.1
1
10
100
0 30 60 90 120 150 180 210
k1
Time (min)
Experimental conditions:
• Feed phase: 0.83 g/l Nd3+ (at 0.5 M HNO3), 0.82 g/l
Nd3+
(at 2 M HNO3), 0.56 g/l Nd3+ (at 3.5 M HNO3) (500 ml)
• Carrier: 0.1M TODGA + 0.5M DHOA in n-dodecane
• Strip phase: distilled water (500 ml)

26. Effect of initial TODGA
concentration26
Experimental conditions:
• Feed phase: 0.56 g/l Nd3+ at
3.5 M HNO3 (500 ml)
• Carrier: TODGA + 0.5 M
DHOA in n-dodecane
• Strip phase: distilled water
(500 ml)
• Feed / strip phase flow
rates: 200 ml/min
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+
ionsleftinfeedReservoir
Time (min)
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+
ionsleftinfeedReservoir
Time (min)
0.05MTODGA-Exp 0.05MTODGA-Pred
0.1MTODGA-Exp 0.1MTODGA-Pred
0.15MTODGA-Exp 0.15MTODGA-Pred

27. Effect of initial feed concentration
27
Experimental conditions:
• Feed phase: Nd3+ at 3 M
HNO3 (500 ml)
• Carrier: 0.1M TODGA +
0.5M DHOA in n-dodecane
• Strip phase: distilled water
(500 ml)
• Feed / strip phase flow
rates: 200 ml/min
0
20
40
60
80
100
0 50 100 150 200
%Nd3+ionsleftinfeedreservoir
Time (min)
0
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
Time (min)
5.36g/l Nd-Exp 5.36g/l Nd-Pred
2.21g/l Nd-Exp 2.21g/l Nd-Pred
1g/l Nd-Exp 1g/l Nd-Pred
0.56g/l Nd-Exp 0.56g/l Nd-Pred

28. Effect of TODGA stoichiometry
28
Experimental conditions:
• Feed phase: 5.36 g/l Nd3+ at 3 M HNO3
(500 ml)
• Carrier: 0.1M TODGA + 0.5M DHOA in
n-dodecane
• Strip phase: distilled water (500 ml)
• Feed / strip phase flow rates: 200
ml/min
 Ansari et al (2005) Solvent Extraction and Ion Exchange, 23: 463–479
 Sasaki et al (2001) Solvent Extraction and Ion Exchange, 19(1): 91–103
Nd3+
(aq) + 3NO3
-
(aq) + 4TODGA(org) Nd(NO3)3 ·4TODGA(org)
0
20
40
60
80
100
0 50 100 150 200 250 300 350
%Nd3+ionsleftinfeedreservoir
Time (min)
5.36g/lNd-Exp
4TODGA (5.36g/lNd)-Pred

29. Effect of feed flow rates
29
Experimental conditions:
• Feed phase: 0.56 g/l Nd3+ at
3 M HNO3 (500 ml)
• Carrier: 0.1M TODGA +
0.5M DHOA in n-dodecane
• Strip phase: distilled water
(500 ml)
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+ionsleftinfeedreservoir
Time (min)
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+ionsleftinfeedreservoir
Time (min)
200 ml/min-Exp
200 ml/min-Pred
100 ml/min-Pred
50 ml/min-Pred

30. Conclusions
 The extraction of Nd3+ ions does not exhibit simple 1st order
behavior
 HNO3 plays a significant role in complexation of Nd3+ ions with
TODGA and needs to be investigated
 The proposed model also hints that ‘n’ may be in the range of
3 < n < 4 for more than 1 g/l Nd3+ concentrations
 Model predictions suggest that extraction of Nd3+ ions is
independent of flow rates for Reynolds number greater than
1.8
 With HFSLM process, 100% extraction of solute ions is
possible with minimal extractant/solvent inventory
 HFSLM would be the preferred choice for extraction (or
selective removal) of acids, pharmaceutical species or anions
30

31. Role of cations H+ and Na+ on the
transport of Nd3+ ions using HFSLM
CASE 231

32. System details
32
 Process  HFSLM
 Feed phase  Nd(NO3)3 in (HNO3+ NaNO3)
media
 Extractant  N,N,N’,N’-tetraoctyl diglycolamide
(TODGA)
 Phase modifier  N,N-dihexyl octanamide
(DHOA)
 Diluent  n-dodecane

33. Equilibration experiment results
33
Sr. No
[HNO3]
(M)
[NaNO3]
(M)
Kd
(for Nd3+
ions)
Kex
1 3 - 140 10042
2 2.5 0.5 110 7816
3 2 1 71 5162
4 1.5 1.5 71 5140
5 1 2 45 3238
6 0.5 2.5 25 1789
7 - 3 5 315
3
),(
3
)(3 ][][ freeorgaq
d
ex
TODGANO
K
K 

[Nd3+]initial = 1 g/l
[TODGA]initial = 0.1 M
Total nitrate ion (NO3
-) concentration is kept constant at 3M

34. HFSLM experimental data
34
Experimental conditions:
• Feed phase: 1 g/l Nd3+ (500
ml)
• Carrier: 0.1M TODGA + 0.5M
DHOA in NPH
• Strip phase: distilled water
(500 ml)
• Feed / strip phase flow
rates: 170 ml/min0
20
40
60
80
100
0 10 20 30 40 50 60
%Nd3+ionsleftinfeedReservoir
Time (min)
0
20
40
60
80
100
0 10 20 30 40 50 60
%Nd3+ionsleftinfeedReservoir
Time (min)
0MNaNO3-3MHNO3-exp
1.5MNaNO3-1.5MHNO3-Exp
3MNaNO3-0MHNO3-Exp

35. HFSLM experimental data
(contd…)35
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0 10 20 30 40 50 60 70
HNO3concentrationinstripreservoir(M)
Time (min)
0.35
0.4
0.45
ervoir(M)
3MHNO3 2MHNO3-1MNaNO3
1.5MHNO3-1.5MNaNO3 0.5MHNO3-2.5MNaNO3
66.88
79.56 80.16
88.29 86.07 84 81.8
0
20
40
60
80
100
0 0.5 1 1.5 2 2.5 3
%ExtractionofNd3+
ions
HNO3 concentration(M) →
←NaNO3 concentration(M)
At the end of 30 minutes
of extraction run
Acid transport to the
strip phase

36. Model Predictions
36
Dm = 6.0 x 10-12 m2/s (Nd-TODGA
complex)
Dhm = 1.2 x 10-10 m2/s (Acid-TODGA
0
20
40
60
80
100
0 30 60 90 120 150
%Nd3+ionsLeftinfeedReservoir
Time (min)
3MHNO3-Exp 3MHNO3-Pred
1.5MHNO3-1.5MNaNO3-Exp 1.5MHNO3-1.5MNaNO3-Pred
3MNaNO3-Exp 3MNaNO3-Pred
0
10
20
30
40
50
60
0 30 60 90 120 150
k1
Time (min)

37. Model Predictions (cont…)
37
0
20
40
60
80
100
0 50 100 150 200%Nd3+
ionsLeftinfeedReservoir
Time (min)
40
60
80
100
d3+ionsLeftinfeedReservoir
3MHNO3-Exp 3MHNO3-Pred
0.5MHNO3-2.5MNaNO3-Exp 0.5MHNO3-2.5MNaNO3-Pred
0.5MHNO3-Exp 0.5MHNO3-Pred
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Nd3+ionsLeftinfeedReservoir
Time (min)
3MHNO3-Exp 3MHNO3-Pred
2MHNO3-1MNaNO3-Exp 2MHNO3-1MNaNO3-Pred
2MHNO3-Exp 2MHNO3-Pred

38. Conclusions
 A very high value of 10042 was observed for Kex
when only HNO3 was used in comparison with
315 for the case of NaNO3 only.
 Extraction of Nd3+ ions is slow in absence of
HNO3 (i.e. only NaNO3 present)
 There is possible participation of H+ ions (HNO3)
in TODGA complexation reactions with trivalent
metal ions
 Highest rate of extraction was achieved with
equimolar concentrations of HNO3 and NaNO3
38

39. Role of cations H+ and Na+ on the
transport of Nd3+ ions using non-
dispersive solvent extraction (NDSX)
and its comparison with HFSLM
CASE 339

40. System details
40
 Process  NDSX and its comparison with
HFSLM
 Feed phase  Nd(NO3)3 in (HNO3+ NaNO3)
media
 Extractant  N,N,N’,N’-tetraoctyl diglycolamide
(TODGA)
 Phase modifier  N,N-dihexyl octanamide
(DHOA)

41. Experimental set-up
41
Cf0
CmsZ
CfZ
Cms0
Feed
reservoir
Organic
reservoir

42. Transport Mechanism
Membrane
phase
Source
phase
Bulk organic
phase
Feed
side
film
Organic
side
film
Cf
Cif
Cimf
Cims
Carrier: TODGA
Diluent: n-
dodecane
42
Cms

43. Equilibrium-based approach
mss
freeorgfex
if
imf
CC
k
m
k
TODGANOK
C
C
k
where



 
1
2
3
),(
3
31
1
1
][][
,
Rate of mass transfer of metal ions (RT)




















1
2
1
1
2
111
k
k
kkD
d
k
C
k
k
C
R
sm
o
f
sf
T
43
)(
1
)3(][
)()(
00
3
0
3
3
0
imsimf
m
sm
msimf
imffex
imf
if
imsimf
m
ifffT
CC
d
D
kD
d
CC
CLNOK
C
C
CC
d
D
CCkR













3
EQUATIO
NS
3 UNKNOWNS Cif, Cimf , Cims

44. Equilibration experiment results
44
Sr. No
[Nd3+
]
(g/l)
[HNO3]
(M)
[TODGA]
(M)
DNd Kex
1 1 3 0.05 2.2 32590
2 1 3 0.15 16.8 2812
3 1 3 0.1 7.1 10042
4 2 3 0.1 2.1 7063
5 3 3 0.1 1.6 5540
6 4 3 0.1 1.1 5447
7 5 3 0.1 1.15 5272
8 1 2 0.1 9.18 8615
9 1 1 0.1 3.24 4388

45. Effect of feed acidity
45
NOTE: Data is at the end of 30 minutes of
extraction run
85.28 83
88.9 90.9
95.37 92.9 95.34
0
20
40
60
80
100
120
0 0.5 1 1.5 2 2.5 3
%ExtractionofNd3+ions
HNO3 concentration(M) →
←NaNO3 concentration(M)

46. Acid balance for NDSX runs
46
Case
Initial aqueous phase
concentrations (M)
Final aqueous phase
concentration of
HNO3 (M)
Drop in HNO3
concentration
(M)HNO3 NaNO3
1 1 - 0.91 0.09
2 2 - 1.8 0.2
3 3 - 2.6 0.4
4 2.5 0.5 2.3 0.2
5 2 1 1.77 0.23
6 1.5 1.5 1.31 0.19
7 1 2 0.88 0.12
8 0.5 2.5 0.44 0.06
9 - 3 Not applicable Not applicable
Experimental
conditions
• Feed phase: 1 g/l Nd3+ (500 ml)
• Extractant: 0.1M TODGA + 0.5M DHOA in NPH
(500 ml)
• Feed / organic phase flow rates: 170 ml/min

47. Effect of acidity
47
0
20
40
60
80
100
0 50 100 150 200
%Nd3+ionsleftinfeedreservoir
Time (min)
3MHNO3-Exp 3MHNO3-Pred
1.5MHNO3-1.5MNaNO3-Exp 1.5MHNO3-1.5MNaNO3-Pred
3MNaNO3-Exp 3MNaNO3-Pred
Dm = 9.0 x 10-12 m2/s (Nd-TODGA
complex)
Dhm = 1.2 x 10-10 m2/s (Acid-TODGA
0
20
40
60
80
100
0 50 100 150 200
k1
Time (min)
For 3M HNO3 case:
• Aqueous-film resistance varies from
7% to 63% during NDSX process
For 3M NaNO3 case:
• Diffusion resistance varies from 96%
to 92% during NDSX process

48. Effect of acidity
48
1MHNO3 only-Exp 1MHNO3 only-Pred
1MHNO3-2MNaNO3-Exp 1MHNO3-2MNaNO3-Pred
0
20
40
60
80
100
0 50 100 150
%Nd3+ionsLeftinfeedReservoir
Time (min)
0
10
20
30
40
50
0 50 100 150
k1
Time (min)
For 1M HNO3 case:
• Diffusion resistance varies from 97%
to 95% during NDSX process
For 1M HNO3-2M NaNO3case:
• Aqueous-film resistance varies from
6% to 44% during NDSX process

49. Comparison of HFSLM with
NDSX49
Experimental conditions:
• Feed phase: 1 g/l Nd3+ (500 ml)
• Extractant: 0.1M TODGA + 0.5M DHOA in n-dodecane (500 ml)
• Feed / organic phase flow rates: 170 ml/min
0
20
40
60
80
100
0 10 20 30 40 50 60
%Nd3+ionsLeftinfeedReservoir
Time (min)
NDSX-Exp NDSX-Pred
HFSLM-Exp HFSLM-Pred
3M HNO3
0
20
40
60
80
100
0 10 20 30 40 50 60
k1
Time (min)
NDSX-Pred
HFSLM-Pred

50. Comparison of HFSLM with
NDSX50
Experimental conditions:
• Feed phase: 1 g/l Nd3+ (500 ml)
• Extractant: 0.1M TODGA + 0.5M DHOA in n-dodecane (500 ml)
• Feed / organic phase flow rates: 170 ml/min
0
20
40
60
80
100
0 10 20 30 40 50 60
%Nd3+ionsLeftinfeedReservoir
Time (min)
NDSX-Exp NDSX-Pred
HFSLM-Exp HFSLM-Pred
1.5M HNO3 - 1.5M NaNO3
0
10
20
30
40
50
60
70
0 10 20 30 40 50 60
k1
Time (min)
NDSX-Pred
HFSLM-Pred

51. Comparison of HFSLM with
NDSX51
Experimental conditions:
• Feed phase: 1 g/l Nd3+ (500 ml)
• Extractant: 0.1M TODGA + 0.5M DHOA in n-dodecane (500 ml)
• Feed / organic phase flow rates: 170 ml/min
0
20
40
60
80
100
0 50 100 150 200
%Nd3+
ionsLeftinfeedReservoir
Time (min)
NDSX-Exp NDSX-Pred
HFSLM-Exp HFSLM-Pred
3M NaNO3
0
2
4
6
8
10
0 50 100 150 200
k1
Time (min)
NDSX-Pred
HFSLM-Pred

52. Conclusions
 For 3M HNO3 case, controlling resistance changes from diffusion
control to aqueous-film resistance control during NDSX run
 For 3M NaNO3 case, diffusion step is predominantly mass transfer
controlling throughout the extraction run
 NDSX is relatively faster than HFSLM extraction under identical
operating conditions (Exception: absence of H+ ions)
 With just NaNO3 present, acid transport is absent hence there is an
enhanced stripping at the strip-organic interface for HFSLM process
and hence HFSLM gives better % extraction
 With just HNO3 present, acid transport to the strip side is
considerable. This suppresses the stripping reaction at the strip-
organic interface for HFSLM and hence NDSX gives comparatively
better % extraction
 NDSX is similar to solvent extraction technique but with large value of
interfacial mass transfer area
52

53. Study of competitive transport of Nd3+
and U6+ ions across HFSLM
CASE 453

54. System details
54
 Process  HFSLM
 Feed phase  Nd(NO3)3 and UO2(NO3)2 in HNO3
media
 Extractant  N,N,N’,N’-tetraoctyl diglycolamide
(TODGA)
 Phase modifier  isodecanol

55. Experimental set-up
55
side...Strip)(
side...Feed)(
011
01
011
01
ssZs
s
s
ffZf
f
f
CCQ
dt
dC
V
CCQ
dt
dC
V

 Cs0
t
Cf0
CfZ
Cs0
CsZ
Qf
Qs
Cf0
t
Cf02
(U6+)
Cf01
(Nd3+)
Cs02
(U6+)
Cs01
(Nd3+)Nd3+ ions
side...Strip)(
side...Feed)(
022
02
022
02
ssZs
s
s
ffZf
f
f
CCQ
dt
dC
V
CCQ
dt
dC
V


U6+ ions

56. Complexation reactions
Neodymium
Transport
Acid Transport
56
Nd3+
(aq) + 3NO3
-
(aq) + 3TODGA(org) Nd(NO3)3 ·3TODGA(org)
H+
(aq) + NO3
-
(aq) + TODGA(org) TODGA·HNO3(org)
Uranium Transport
UO2
2+
(aq) + 2NO3
-
(aq) + nTODGA(org) UO2(NO3)2 ·nTODGA(org)
])()([])()([3][][ 232333 nfreeinitial TODGANOUOnTODGANONdTODGATODGA 
TODGA balance
}{}{2}{3][][ )(0)0(0)(02)0(02)(01)0(01)0(,3)(,3 tthfthfttftfttftftfttf CCCCCCNONO 




Nitrate ion
balance

57. Transport Mechanism
Membrane
phase
Source
phase
Receiver
phase
Feed
side
film
Strip
side
film
Carrier: TODGA
Diluent: n-
dodecane
57
Cf1
Cif1
Cimf1
Cims1
Cis1 = Cs1
Cf2 Cfmf2
Cims2
Cis2 = Cs2
Cif2
Neodymium
ionsUranium

58. Module exit concentrations




























































s
f
fifs
f
s
f
fif
s
s
f
fifs
f
f
fZ
Q
Q
m
ur
ZK
Q
Q
m
Q
Q
m
ur
ZK
Cm
Q
Q
m
ur
ZK
Q
Q
mC
C
1
1
1
1
1
0111
1
101
1
1
2
exp1
1
2
exp11
2
exp1


Nd3+ ions
)( 101011 fZf
s
f
ssZ CC
Q
Q
CC 
58




























































s
f
fifs
f
s
f
fif
s
s
f
fifs
f
f
fZ
Q
Q
m
ur
ZK
Q
Q
m
Q
Q
m
ur
ZK
Cm
Q
Q
m
ur
ZK
Q
Q
mC
C
2
2
2
2
2
0222
2
202
2
1
2
exp1
1
2
exp11
2
exp1


)( 202022 fZf
s
f
ssZ CC
Q
Q
CC 
UO2
2+ ions

59. Problem Statement
3
210
3
31
1
1
11
0
1
111
3
210
3
31
1
1
)3(][
)()(
)3(][
imfimffif
imf
ex
imsimf
m
ifffT
imsimsss
ims
ex
nCCLNOC
C
K
CC
d
D
CCkR
nCCLNOC
C
K







)(][
)()(
)(][
03
0
03
himffhif
himf
H
himshimf
hm
hifhffhT
himsshs
hims
H
CLNOC
C
K
CC
d
D
CCkR
CLNOC
C
K







9 EQUATIONS
9 UNKNOWNS
Cif1, Cimf1, Cims1
Cif2, Cimf2, Cims2
Chif, Chimf, Chims
59
n
imfimffif
imf
ex
imsimf
m
ifffT
n
imsimsss
ims
ex
nCCLNOC
C
K
CC
d
D
CCkR
nCCLNOC
C
K
)3(][
)()(
)3(][
210
3
32
2
2
22
0
2
222
210
3
32
2
2








60. TODGA stoichiometry
60
[HNO3] n Major extracted species Log Kex
1 M 1.74 UO2(NO3)2·(TODGA)2 2.14
3 M 1.18 UO2(NO3)2·(TODGA) 1.03
(Source: Panja et al., Journal of Membrane Science, 337 (2009) 274–
281)
For Uranyl nitrate - TODGA complexation
The value of Kex for 2M HNO3 system was estimated by
interpolation of the data in the above table and found to be Log
(Kex) = 1.6

61. Model validation for 3M HNO3
61
• Feed phase: 1 g/l Nd3+ ions + 1g/l
UO2
2+ ions at 3M HNO3 (500 ml)
• Carrier: 0.1M TODGA + 5% (v/v)
isodecanol in n-dodecane
• Strip phase: distilled water (500 ml)
• Feed / strip phase flow rates: 170
Dm1 = 1.1 x 10-11 m2/s (Nd-TODGA complex)
Dm2 = 4 x 10-12 m2/s (U-TODGA complex)
Dhm = 1.2 x 10-10 m2/s (HNO3-TODGA
complex)
0
10
20
30
40
50
0 10 20 30 40 50 60 70 80
k1
Time (min)
Nd-Predicted
U-Predicted
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Metalionsleftinfeedreservoir
Time (min)
Nd-Exp Nd-Pred
U-Exp U-Pred

62. Model validation for 3M HNO3
62
0
20
40
60
80
100
0 20 40 60 80 100
%Metalionsleftinfeedreservoir
Time (min)
Nd-Exp Nd-Pred
U-Exp U-Pred
0
20
40
60
80
100
0 20 40 60 80 100
%Metalionsleftinfeedreservoir
Time (min)
Nd-Exp Nd-Pred
U-Exp U-Pred
[UO2
2+]initial = 2 g/l [UO2
2+]initial = 3 g/l

63. Model validation for 2M HNO3
63
0
20
40
60
80
100
0 30 60 90 120 150
%Metalionsleftinfeedreservoir
Time (min)
Nd-Exp Nd-Pred
U-Exp U-Pred
0
20
40
60
80
100
0 30 60 90 120 150
%Metalionsleftinfeedreservoir
Time (min)
Nd-Exp Nd-Pred
U-Exp U-Pred
1
TODG
A
2
TODG
A

64. Conclusions
64
 TODGA provokes competition between Nd3+ and
UO2
2+ ions
 There is significant transport of both the Nd3+ and
UO2
2+ ions
 The rate of extraction of Nd3+ ions is approximately
six times than that of UO2
2+ ions
 100% extraction of Nd3+ ions takes place in almost
30 minutes even with high concentration of UO2
2+
ions
 There is an enhancement in the rate of extraction of
UO2
2+ ions once 100% extraction of Nd3+ ions has
been completed

65. Extraction of Co2+ ions using bis(2-
ethylhexyl) phosphoric acid (D2EHPA)
in HFSLM
CASE 565

66. System details
66
 Process  HFSLM
 Feed phase  CoSO4 7H2O solution (dissolved in a
buffer of sodium acetate and acetic acid)
 Extractant  di-2-ethylhexyl phosphoric acid
(D2EHPA)
 Diluent  Kerosene

67. Complexation reaction
Co2+
(aq) + 2(HR)2(org) CoR2·2(HR)(org) + 2H+
2
)(2
)(
)(
2
)(2
2
)(2)(
2
2
)()(2
])[(
][
][
)](2[
tcoefficienonDistributi
])[(][
][)](2[
constantExtraction

















org
aq
dex
aq
org
d
orgaq
aqorg
ex
HR
H
KK
Cu
HRCuR
K
HRCu
HHRCuR
K
Metal Transport
67
(D2EHPA) (metal
complex)

68. Transport Mechanism
Membrane
phase
Source
phase
Receiver
phase
Feed
side
film
Strip
side
film
Cf
Cif
Cimf
Cims
Cis
Carrier: D2EHPA
Diluent: Kerosene
68
Chf
Chif
Chis
Chs
Cs
[(HR)2]free,s
[(HR)2]free,f

69. Equilibrium-based approach
69
1
2
2
),(2
2
2
),(2
1
][
])[(
][
])[(
k
k
m
H
HR
K
C
C
k
H
HR
K
C
C
k
s
freeorg
ex
is
ims
f
freeorg
ex
if
imf



















With steady state assumption we have,
K
C
k
k
C
k
k
kkD
d
k
C
k
k
C
R
sf
sm
o
f
sf
T
1111
1
2
1
2
1
1
2



























Co2+ transfer rate
)(
)(
)(
sissT
imsimf
o
m
TCMT
ifffT
CCkR
CC
d
D
RR
CCkR



H+ transfer rate
)(2
)(
)(
imsimf
o
m
hT
hishsshT
hfhiffhT
CC
d
D
R
CCkR
CCkR



)( sfT mCCKR 

70. Model Equations (cont..)




























































s
f
fifs
f
s
f
fif
s
s
f
fifs
f
f
fZ
Q
Q
m
ur
KZ
Q
Q
m
Q
Q
m
ur
KZ
mC
Q
Q
m
ur
KZ
Q
Q
mC
C
1
2
exp1
1
2
exp11
2
exp1 00


Module exit concentrations:
)( 00 fZf
s
f
ssZ CC
Q
Q
CC 
For feed phase…
For strip phase…
70

71. Problem Statement
6 EQUATIONS
6 UNKNOWNS
Cif, Cimf, Cims
Cis, Chif, Chis
71
Co2+
(aq) + 2(HR)2(org) CoR2·2(HR)(org) + 2H+
)(2)(
)()(
)2(
0
0
2
0
2
imsimf
m
hfhiff
imsimf
m
fiff
imfif
hifimf
ex
CC
d
D
CCk
CC
d
D
CCk
CLC
CC
K




)(2)(
)()(
)2(
0
0
2
0
2
imsimf
m
hishss
imsimf
m
siss
imsis
hisims
ex
CC
d
D
CCk
CC
d
D
CCk
CLC
CC
K





72. Equilibration data
72
Aqueous
[Co2+
]initial
mM
D2EHPA
conc
%(v/v)
Organic
[(HR)2]initial
mM
Aqueous
[Co2+
]eqm
mM
Organic
[(HR)2]eqm
mM
Organic
[CoR2(HR)2]eqm
mM
Aqueous
[H+
]eqm
mM
Kex
1 15 445.807 0.796 445.399 0.204 0.409 2.16 x 10-7
1 20 594.410 0.608 593.625 0.392 0.785 1.13 x 10-6
3 10 297.205 2.685 296.575 0.315 0.630 5.29 x 10-7
3 15 445.807 2.225 444.258 0.775 1.549 4.23 x 10-6
3 20 594.410 1.790 591.990 1.210 2.420 1.13 x 10-5
2
)(2)(
2
2
)()(2
])[(][
][)](2[
orgaq
aqorg
ex
HRCu
HHRCuR
K 




73. Why buffer the feed phase?
73
0
20
40
60
80
100
0 10 20 30 40 50 60
%Extractionofcobaltions
Time (min)
0
20
40
60
80
100
0 40 80 120 160
%Extractionofcobaltions
Time (min)
Buffered feed (4.5 pH) Non-buffered feed
Operating conditions:
Feed = 3mM Co2+ ions
Extractant = 20% (v/v) D2EHPA
in kerosene
Strip acid = 2M H2SO4
Dm = 1.5 x 10-10 m2/s (Cobalt-D2EHPA
complex)

74. Effect of feed pH
74
Operating conditions:
Feed = 3mM Co2+ ions
Ligand = 20% (v/v)
D2EHPA
Flow rate = 100
ml/min (both)
Strip acid = 2M H2SO4
0
20
40
60
0 10 20 30 40 50 60 70
%Extractionofcobalti
Time (min)
6pH-Exp 6pH-Pred
4.5pH-Exp 4.5pH-Pred
3.5pH-Exp 3.5pH-Pred
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Extractionofcobaltion
Time (min)

75. Effect of initial feed concentration
75
Operating conditions:
Feed = Buffer (4.5 pH)
Ligand = 20% (v/v) D2EHPA
Flow rate = 100
ml/min (both)
3mMCo-Exp 3mMCo-Pred
2mMCo-Exp 2mMCo-Pred
1mMCo-Exp 1mMCo-Pred
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Extractionofcobaltions
Time (min)
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60 70
Concentrationofcobaltions
instripreservoir(mM)
Time (min)

76. Effect of initial D2EHPA
concentration76
Operating conditions:
Feed = 3mM Co2+ ions
Buffer (4.5 pH)
Flow rate = 100
ml/min (both)
Strip acid = 2M H2SO4
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Extractionofcobaltions
Time (min)
0
20
40
60
0 10 20 30 40 50 60 70
%Extractionofcobalti
Time (min)
10%D2EHPA-Exp 10%D2EHPA-Pred
20%D2EHPA-Exp 20%D2EHPA-Pred
30%D2EHPA-Exp 30%D2EHPA-Pred

77. Effect of strip phase acidity
77
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Extractionofcobaltions
Time (min)
Operating conditions:
Feed = 3mM Co2+ ions
Buffer (4.5 pH)
Ligand = 20% (v/v) D2EHPA
Flow rate = 100
ml/min (both)
0
20
40
60
0 10 20 30 40 50 60 7
%Extractionofcobaltions
Time (min)
3MH2SO4-Exp 3MH2SO4-Pred
2MH2SO4-Exp 2MH2SO4-Pred
1MH2SO4-Exp 1MH2SO4-Pred
0.5MH2SO4-Exp 0.5MH2SO4-Pred

78. Effect of flow rates
78
0
20
40
60
80
100
0 10 20 30 40 50 60 70
%Extractionofcobaltions
Time (min)
Operating conditions:
Feed = 3mM Co2+ ions
Buffer (4.5 pH)
Ligand = 20% (v/v) D2EHPA
Strip acid = 2M H2SO4
0
20
40
60
80
0 10 20 30 40 50 60 70
%Extractionofcobaltions
Time (min)
100 ml/min-Exp 100 ml/min-Pred
200 ml/min-Exp 200 ml/min-Pred
300 ml/min-Exp 300 ml/min-Pred
400 ml/min-Exp 400 ml/min-Pred

79. Conclusions
 The counter-ions (H+) transport across the HFSLM affects the
transport of Co2+ ions. Hence, buffer is added to the feed
phase
 Higher the feed phase pH higher is the rate of extraction of
Co2+ ions
 The strip acidity has no effect on the transport of Co2+ ions in
the range of 0.5-3M H2SO4
 Increase in D2EHPA concentration yields in higher rates of
extraction of Co2+ ions
 The % transport of Co2+ ions is independent of flow rates
Reynolds number greater than 3.5
 The increase in flow rate results in increased feed-side mass
transfer coefficient (kf); it increases from 2 x 10-5 m/s at 100
79

80. Publications
80

81. Publications (cont…)
81

82. Publications (cont…)
82

83. Publications (Under peer review)
Submitted to Separation Science and Technology
 P. V. Vernekar, Y. D. Jagdale, A. W. Patwardhan , A.
V. Patwardhan , S. A. Ansari , P. K. Mohapatra & V.
K. Manchanda, Non-dispersive solvent extraction of
Neodymium using N,N,N',N'-tetraoctyl diglycolamide
(TODGA).
Submitted to Separation Science and Technology
 P. V. Vernekar, Y. D. Jagdale, A. W. Patwardhan , A.
V. Patwardhan , S. A. Ansari , P. K. Mohapatra & V.
K. Manchanda, Simultaneous extraction of Neodymium
and Uranium using hollow fiber supported liquid
membrane.
83

84. Conferences
84
 P. V. Vernekar, Y. D. Jagdale, A. W. Patwardhan , A. V.
Patwardhan , S. A. Ansari , P. K. Mohapatra & V. K.
Manchanda, Mathematical model for the extraction of metal
ions using hollow fiber supported liquid membrane operated in
a recycling mode, DAE-BRNS Symposium on Emerging
Trends in Separation Science and Technology (SESTEC-
2012), February 27 - March 01, 2012, SVKM’s Mithibai
College, Vile Parle, Mumbai – 400 056, India. (Oral
Presentation)
 P. V. Vernekar, Y. D. Jagdale, Mathematical modelling for
liquid membrane separation processes in hollow fibre
membrane Contactors, International Conference on Advances
in Chemical Engineering (ACE-2013), February 22-24, 2013,
IIT Roorkee, India. (Oral Presentation)

85. Thank You
85