Effects of charge density on water splitting at cation-exchange membrane surface in the over-limiting current region

2004 ◽  
Vol 21 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Moon-Sung Kang ◽  
Yong-Jin Choi ◽  
Seung-Hyeon Moon
Keyword(s):  
Charge Density ◽  
Cation Exchange ◽  
Water Splitting ◽  
Membrane Surface ◽  
Cation Exchange Membrane ◽  
Limiting Current ◽  
Current Region ◽  
Exchange Membrane

scholarly journals Enhancing Ion Transfer in Overlimiting Electrodialysis of Dilute Solutions by Modifying the Surface of Heterogeneous Ion-Exchange Membranes

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Natalia Pismenskaya ◽  
Nadezhda Melnik ◽  
Ekaterina Nevakshenova ◽  
Kseniya Nebavskaya ◽  
Victor Nikonenko
Keyword(s):  
Mass Transfer ◽  
Surface Layer ◽  
Ion Exchange ◽  
Cation Exchange ◽  
Water Splitting ◽  
Anion Exchange ◽  
Membrane Surface ◽  
Anion Exchange Membrane ◽  
Cation Exchange Membrane ◽  
Exchange Membrane

The desalination of dilute NaCl solutions with heterogeneous Russian commercial and modified ion-exchange membranes was studied in a laboratory cell imitating desalination channels of large-scale electrodialysers. The modification was made by casting a thin film of a Nafion-type material on the surface of cation-exchange membrane, and by processing with a strong polyelectrolyte the surface of anion-exchange membrane. It was shown that the modifications resulted in an increase of mass transfer coefficient and in a decrease in water splitting rate, both by up to 2 times. The effect of mass transfer growth is explained by higher surface hydrophobicity of the modified membrane that enhances electroconvection. The decrease in water splitting rate in the case of cation-exchange membrane is due to homogenization of its surface layer. In the case of anion-exchange membrane the effect is due to grafting of quaternary ammonium bases onto the original membrane surface layer. The suppression of water splitting favors development of electroconvection. In turn, intensive electroconvection contributes to deliver salt ions to membrane surface and thus reduces water splitting.

scholarly journals Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
AHM Golam Hyder ◽  
Brian A. Morales ◽  
Malynda A. Cappelle ◽  
Stephen J. Percival ◽  
Leo J. Small ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Cation Exchange ◽  
Current Density ◽  
Feed Solution ◽  
Laboratory Scale ◽  
Cation Exchange Membrane ◽  
Limiting Current ◽  
Ion Exchange Membranes ◽  
Experimental Apparatus ◽  
Exchange Membrane

Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane.

scholarly journals The Development of Electroconvection at the Surface of a Heterogeneous Cation-Exchange Membrane Modified with Perfluorosulfonic Acid Polymer Film Containing Titanium Oxide

Membranes ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 125
Author(s):  
Violetta Gil ◽  
Mikhail Porozhnyy ◽  
Olesya Rybalkina ◽  
Dmitrii Butylskii ◽  
Natalia Pismenskaya
Keyword(s):  
Mass Transfer ◽  
Cation Exchange ◽  
Polymer Film ◽  
Tio2 Nanoparticles ◽  
Cation Exchange Membrane ◽  
Limiting Current ◽  
Perfluorosulfonic Acid ◽  
Heterogeneous Cation Exchange Membrane ◽  
Exchange Membrane ◽  
Stimulation Of

One way to enhance mass transfer and reduce fouling in wastewater electrodialysis is stimulation of electroconvective mixing of the solution adjoining membranes by modifying their surfaces. Several samples were prepared by casting the perfluorosulfonic acid (PFSA) polymer film doped with TiO2 nanoparticles onto the surface of the heterogeneous cation-exchange membrane MK-40. It is found that changes in surface characteristics conditioned by such modification lead to an increase in the limiting current density due to the stimulation of electroconvection, which develops according to the mechanism of electroosmosis of the first kind. The greatest increase in the current compared to the pristine membrane can be obtained by modification with the film being 20 μm thick and containing 3 wt% of TiO2. The sample containing 6 wt% of TiO2 provides higher mass transfer in overlimiting current modes due to the development of nonequilibrium electroconvection. A 1.5-fold increase in the thickness of the modifying film reduces the positive effect of introducing TiO2 nanoparticles due to (1) partial shielding of the nanoparticles on the surface of the modified membrane; (2) a decrease in the tangential component of the electric force, which affects the development of electroconvection.

Evolution with Time of Hydrophobicity and Microrelief of a Cation-Exchange Membrane Surface and Its Impact on Overlimiting Mass Transfer

2012 ◽  
Vol 116 (7) ◽  
pp. 2145-2161 ◽  
Author(s):  
Natalia D. Pismenskaya ◽  
Victor V. Nikonenko ◽  
Nadezhda A. Melnik ◽  
Kseniya A. Shevtsova ◽  
Elena I. Belova ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Cation Exchange ◽  
Membrane Surface ◽  
Cation Exchange Membrane ◽  
Exchange Membrane ◽  
Evolution With Time
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