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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