scholarly journals In-Situ Combination of Bipolar Membrane Electrodialysis with Monovalent Selective Anion-Exchange Membrane for the Valorization of Mixed Salts into Relatively High-Purity Monoprotic and Diprotic Acids

Membranes ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 135 ◽  
Author(s):  
Haiyang Yan ◽  
Wei Li ◽  
Yongming Zhou ◽  
Muhammad Irfan ◽  
Yaoming Wang ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Current Density ◽  
High Purity ◽  
Anion Exchange Membrane ◽  
Discharge Process ◽  
Bipolar Membrane ◽  
Liquid Discharge ◽  
Bipolar Membrane Electrodialysis ◽  
Mixed Salts ◽  
Exchange Membrane

The crystalized mixed salts from the zero liquid discharge process are a hazardous threat to the environment. In this study, we developed a novel electrodialysis (SBMED) method by assembling the monovalent selective anion-exchange membrane (MSAEM) into the bipolar membrane electrodialysis (BMED) stack. By taking the advantages of water splitting in the bipolar membrane and high perm-selectivity of MSAEM for the Cl− ions against the SO42− ions, this combination allows the concurrent separation of Cl−/SO42− and conversion of mixed salts into relatively high-purity monoprotic and diprotic acids. The current density has a significant impact on the acid purity. Both the monoprotic and diprotic acid purities were higher than 80% at a low current density of 10 mA/cm2. The purities of the monoprotic acids decreased with an increase in the current density, indicating that the perm-selectivity of MSAEM decreases with increasing current density. An increase in the ratio of monovalent to divalent anions in the feed was beneficial to increase the purity of monoprotic acids. High-purity monoprotic acids in the range of 93.9–96.1% were obtained using this novel SBMED stack for treating simulated seawater. Therefore, it is feasible for SBMED to valorize the mixed salts into relatively high-purity monoprotic and diprotic acids in one step.

scholarly journals Investigation of NiFe-Based Catalysts for Oxygen Evolution in Anion-Exchange Membrane Electrolysis

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1720
Author(s):  
Sabrina Campagna Zignani ◽  
Massimiliano Lo Faro ◽  
Stefano Trocino ◽  
Antonino Salvatore Aricò
Keyword(s):  
Single Cell ◽  
Anion Exchange ◽  
Oxygen Evolution ◽  
Current Density ◽  
Electrochemical Behaviour ◽  
Stress Test ◽  
Supporting Electrolyte ◽  
Anion Exchange Membrane ◽  
Operating Conditions ◽  
Exchange Membrane

NiFe electrodes are developed for the oxygen evolution reaction (OER) in an alkaline electrolyser based on an anion exchange membrane (AEM) separator and fed with diluted KOH solution as supporting electrolyte. This study reports on the electrochemical behaviour of two different NiFe-oxide compositions (i.e., Ni1Fe1-oxide and Ni1Fe2-oxide) prepared by the oxalate method. These catalysts are assessed for single-cell operation in an MEA including a Sustainion™ anion-exchange membrane. The electrochemical polarization shows a current density of 650 mA cm−2 at 2 V and 50 °C for the Ni1Fe1 anode composition. A durability test of 500 h is carried out using potential cycling as an accelerated stress-test. This shows a decrease in current density of 150 mA cm−2 mainly during the first 400 h. The performance achieved for the anion-exchange membrane electrolyser single-cell based on the NiFeOx catalyst appears promising. However, further improvements are required to enhance the stability under these operating conditions.

scholarly journals The Novel Strategy for Increasing the Efficiency and Yield of the Bipolar Membrane Electrodialysis by the Double Conjugate Salts Stress

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 343 ◽  
Author(s):  
Dong Wang ◽  
Wenqiao Meng ◽  
Yunna Lei ◽  
Chunxu Li ◽  
Jiaji Cheng ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cation Exchange ◽  
Ammonium Sulfate ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Anion Exchange Membrane ◽  
Ammonium Sulfate Solution ◽  
Bipolar Membrane ◽  
Bipolar Membrane Electrodialysis ◽  
Exchange Membrane

To improve sulfuric acid recovery from sodium sulfate wastewater, a lab-scale bipolar membrane electrodialysis (BMED) process was used for the treatment of simulated sodium sulfate wastewater. In order to increase the concentration of sulfuric acid (H2SO4) generated during the process, a certain concentration of ammonium sulfate solution was added into the feed compartment. To study the influencing factors of sulfuric acid yield, we prepared different concentrations of ammonium sulfate solution, different feed solution volumes, and different membrane configurations in this experiment. As it can be seen from the results, when adding 8% (NH4)2SO4 into 15% Na2SO4 under the experimental conditions where the current density was 50 mA/cm2, the concentration of H2SO4 increased from 0.89 to 1.215 mol/L, and the current efficiency and energy consumption could be up to 60.12% and 2.59 kWh/kg, respectively. Furthermore, with the increase of the volume of the feed compartment, the concentration of H2SO4 also increased. At the same time, the configuration also affects the final concentration of the sulfuric acid; in the BP-A-C-BP (“BP” means bipolar membrane, “A” means anion exchange membrane, and “C” means cation exchange membrane; “BP-A-C-BP” means that two bipolar membranes, an anion exchange membrane, and a cation exchange membrane are alternately arranged to form a repeating unit of the membrane stack) configuration, a higher H2SO4 concentration was generated and less energy was consumed. The results show that the addition of the double conjugate salt is an effective method to increase the concentration of acid produced in the BMED process.

scholarly journals High carbonate ion conductance of a robust PiperION membrane allows industrial current density and conversion in a zero-gap carbon dioxide electrolyzer cell

2020 ◽  
Vol 13 (11) ◽  
pp. 4098-4105
Author(s):  
B. Endrődi ◽  
E. Kecsenovity ◽  
A. Samu ◽  
T. Halmágyi ◽  
S. Rojas-Carbonell ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Anion Exchange ◽  
Current Density ◽  
Anion Exchange Membrane ◽  
Ion Conductance ◽  
Carbonate Ion ◽  
High Carbonate ◽  
Current Densities ◽  
Exchange Membrane ◽  
Partial Current

A new anion exchange membrane (PiperION) in conjunction with a tailored zero-gap electrolyzer cell allows unprecedented partial current densities.

High-performance anion exchange membrane water electrolyzers with a current density of 7.68 A cm-2 and durability of 1000 h

2021 ◽  
Author(s):  
Nanjun Chen ◽  
Sae Yane Baek ◽  
Ju Yeon Lee ◽  
Jong Hyeong Park ◽  
So Young Lee ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Current Density ◽  
High Performance ◽  
Low Cost ◽  
New Technology ◽  
Anion Exchange Membrane ◽  
Proton Exchange ◽  
Exchange Membrane ◽  
A Current ◽  
High Purity Hydrogen

Low-cost anion exchange membrane (AEM) water electrolyzers (AEMWEs) are a new technology to produce high-purity hydrogen; however, their current density and durability are far lower than those of proton exchange...

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