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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

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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

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

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.

Figure 2 schematic representation of mass transfer through a liquid membrane

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.

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

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.

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

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)

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.

(7)( , ) ( , ) ( ( , )f f Af

f Af f Af f Af Af f

A D Cq 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 ( )wf

w Nd

M TD

2

f iA N r

( , )n

Af Ex Afr k C x t (8)

(9)

(10)

3 3

f,in f,out

3

f,in

Nd NdExtraction(%) 100

Nd

3 3

exp

3

exp

Nd NdAbsolute error (%) = 100

Nd

cal

(11)

(12)

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

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

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

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%.