Accurate Determination of Electrical Potential on Ion Exchange Membranes in Reverse Electrodialysis

Reverse electrodialysis is a promising membrane technology to generate energy from controlled mixing of water streams of different salinities. Electrical potentials generate on the ion exchange membranes (IEMs) when selective transport of cations and anions across the membranes driven by concentration difference. The accurate determination of the potentials developed on the IEMs is critical to fairly assess the feasibility of the technology. The Nernst–Planck–Poisson (NPP) equations for IEMs (the membranes with fixed charge) were solved numerically with the boundary updating scheme. The validity of this numerical method was verified by the identical values of Donnan potential obtained with the well-established analytical methods. The suitability and applicability of the classic Teorell–Meyer–Siever (TMS) model were assessed by comparison to the simulation results from the numerical method.

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Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19921905 ◽

1992 ◽

Vol 57 (9) ◽

pp. 1905-1914

Author(s):

Miroslav Bleha ◽

Věra Šumberová

Keyword(s):

Experimental Data ◽

Ion Exchange ◽

Total Content ◽

Distribution Coefficients ◽

Exchange Capacity ◽

Ion Exchange Membranes ◽

Ion Exchange Capacity ◽

Equilibrium Sorption ◽

Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

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The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate

Membranes ◽

10.3390/membranes11020135 ◽

2021 ◽

Vol 11 (2) ◽

pp. 135

Author(s):

Yash Dharmendra Raka ◽

Robert Bock ◽

Håvard Karoliussen ◽

Øivind Wilhelmsen ◽

Odne Stokke Burheim

Keyword(s):

Ion Exchange ◽

Waste Heat ◽

Ammonium Bicarbonate ◽

Operating Efficiency ◽

Membrane Thickness ◽

Ion Exchange Membranes ◽

Reverse Electrodialysis ◽

Ohmic Resistance ◽

Production Of Hydrogen ◽

The Impact

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10−7 kg mmem−2s−1 with a waste heat requirement of 344 kWh kg−1 hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kgH2−1.

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