Elimination of Concentration Polarization Phenomenon and

Elimination of Concentration Polarization Phenomenon
and Facilitation of Counter Ion Transfer through Ion
Exchange Membrane in Electromembrane Processes.
Ridha Zerdoumi a,b, Kafia Oulmi a, Salah Benslimane a
a Laboratory of Chemistry and Environmental Chemistry, University of Batna,
05000 Batna, Algeria.
b Department of Chemistry, Faculty of Science, University of Biskra,
07000 Biskra, Algeria.
E-mail address: [email protected]
Ion exchange membranes (IEM) are polymeric ion conducting materials. They have
various applications such as fuel cell (PEMFC), electrochemical synthesis (Cl 2 / NaOH),
desalination, purification, separation and environment. Despite these applications, several
aspects are still unknown, such as the membrane structure, the conduction mechanisms and
concentration polarization. Concentration polarization is a common phenomenon to all
systems operating selective ionic transfers through an interface. This phenomenon arises
from the difference of ion mobility in the solution and in the membrane. It is the main
obstacle in electro-membrane progress. Therefore, the study of this phenomenon is
essential and very important. In this research we studied the effect of the ammonia buffer
(NH3/NH4+) on the counter-ion transfer through the anionic and the cationic exchange
membranes AMX and CMX respectively. The results show that the ammonia addition
facilitates the counter-ion transfer in both cases and gives a total elimination of the system
polarization, but with different behaviours of CMX and AMX membranes as shown
(Fig.1).
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0.013
0.012
0.011
0.011
0.010
0.010
0.009
0.009
0.008
0.008
0.007
0.007
0.006
0.006
0.005
0.005
0.004
(NH4)2SO4
(NH4)2SO4
(NH4)2SO4
(NH4)2SO4
(NH4)2SO4
0.003
0.002
0.001
0.05N MEC
0.05N+0.01N NH3
0.05N+0.05N NH3
0.05N+0.075N NH3
0.05N+0.1N NH3
0.000
0.0
0.5
1.0
1.5
2.0
E (V)
2.5
3.0
0.004
0.003
0.002
0.001
0.000
3.5
0.018
0.0
0.5
1.0
1.5
2.0
2.5
3.0
NH4Cl 0.05N MEA
0.016
NH4Cl 0.05N + 0.010N NH3
0.014
NH4Cl 0.05N + 0.025N NH3
0.012
NH4Cl 0.05N + 0.050N NH3
0.010
NH4Cl 0.05N + 0.100N NH3
0.018
0.016
NH4Cl 0.05N + 0.005N NH3
0.014
0.012
NH4Cl 0.05N + 0.075N NH3
2
0.0
0.012
J (A / Cm )
2
J (A/Cm )
0.013
0.010
0.008
0.008
0.006
0.006
0.004
0.004
0.002
0.002
0.000
0.000
0.0
0.5
1.0
1.5
2.0
2.5
3.0
E (V)
Figure 1. Effect of ammonia addition on the I-V curve: left: (NH4)2SO4 through CMX
cation exchange membrane; right: NH4Cl through AMX anion exchange membrane.
ise140656

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