This presentation was done in June 2014 by one of our participants in ICST and ICBELSH conferences.

1. 1
Presented by
Wasamon Konaem
Simulation for synergistic extraction of
neodymium ions with hollow fiber supported
liquid membrane
Department of Chemical Engineering
Faculty of Engineering, Chulalongkorn University

2. 2
Neodymium is the raw material used in high-strength permanent
magnets (Nd–B–Fe)
Rare earth elements (REEs) have similar chemical and physical
properties. Separation of individual REE was a difficult.
The high value of REE depends on their effective separation
into high purity compounds
HFSLM is an effective method to treat a very low concentration
of metal ions

3.  Inside that shell, there are many thin fibers running the length
of the shell, all in nice, neat rows
 The HFSLM system composed of feed phase, liquid phase and
stripping phase.
 Feed and stripping phase are separated by a membrane
embedded with extractant.
Figure 1 HFSLM module

4. 1.Very small and low release of extractant.
2.Extraction and stripping can be carried
out simultaneously in one equipment.
3.High contact surface are a per unit
extract or volume.
4.Independent control of process flow
rates eliminating loading and flooding.
5.Lower capital and operating costs.
6.Lower energy consumption.

5. Figure 2 schematic representation of mass transfer through a liquid membrane

6. Co-operative effect of two (or
more) extractants where the efficiency
for the combination is greater than the
largest individual distribution.
The first, is major extractant and
the other is donor electron.

7. Feed : Nd(III) 100 mg/L in nitric acid
solution, pH = 4.5, on tube side
Extractants :
Acidic extractant was 0.5 M D2EHPA
(A)
Neutral donor was 0.5 M TOPO (B)
Stripping : 1 M H2SO4, on shell side
Mode : Once through, countercurrent
flow
Figure 3 schematic representation of the counter
current flow diagram in HFSLM
Figure 4 The molecular structure of extractants (A)
D2EHPA and (B) TOPO

8. Step 1: Nd(III) ion in the feed
solution is transport to feed-
membrane interface.
Nd(III) ion is reacted with
D2EHPA and TOPO yields a
stable complex compound
(1)
(2)
(3)
Figure 5 Schematic of Nd(III) transport across HFSLM.

9. Step 2: neodymium complex
compound diffuses from
membrane phase to stripping
phase.
Step 3: neodymium complex react
with stripping solution (H2SO4)
at the membrane-stripping
interface

10. Step 4: Nd3+is transferred into the stripping
solution the extractant diffuses back to the
feed phase to react again with Nd3+ In feed
solution
(4)
(5)
(6)

11. Assumption :
 The physical properties in feed phase are constant.
 The concentration of neodymium ions in the radial
direction is constant because the inside diameter of
hollow fiber is very small. Therefore means that the
diffusion fluxes of neodymium ions in the feed phase exist
only in the axial direction.
 Perfect mixing occur in the small cross sectional area of
the inner tube. Therefore the concentration of neodymium
ions in the radial direction is constant.
 Only complex species, not neodymium ions, are transport
through the liquid membrane phase.
 The forwards reaction is dominant.

12. (7)( , ) ( , ) ( ( , )
f f Af
f Af f Af f Af Af f
A D C
q C x t q C x x t xA r C x x t xA
x t

          
 
3
8 0.5
0.6
7.4 10 ( )w
f
w Nd
M T
D

  



2
f iA N r 
( , )n
Af Ex Afr k C x t (8)
(9)
(10)

13. 3 3
f,in f,out
3
f,in
Nd Nd
Extraction(%) 100
Nd
 

      
 
  
3 3
exp
3
exp
Nd Nd
Absolute error (%) = 100
Nd
cal
 

      

  
(11)
(12)

14. Figure 6 Experimental and model of concentration of Nd(III) in feed solution

15. Figure 7 Experimental and model of percentage extraction of Nd(III) in feed solution

16. Figure 8 Effect of volumetric flowrate in feed solution on percentage extraction of Nd(III)

17.  A hollow fiber supported liquid membrane
system using 0.5M D2EHPA and 0.5M TOPO
mixtures as the synergistic extractant
 Simulation results of the developed models
are in good agreement with the experimental
data reported.
 The average percentage of absolute error is
8.95%.