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

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 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.

scholarly journals Mass transfer across cation exchange membrane.

1989 ◽  
Vol 22 (4) ◽  
pp. 352-357 ◽  
Author(s):  
Katsuroku Takahashi ◽  
Katsumi Tsuboi ◽  
Hiroshi Takeuchi
Keyword(s):  
Mass Transfer ◽  
Cation Exchange ◽  
Cation Exchange Membrane ◽  
Exchange Membrane
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