Concentration polarization and second-kind electrokinetic instability at an ion-selective surface admitting normal flow

2011 ◽  
Vol 23 (7) ◽  
pp. 072003 ◽  
Author(s):  
Aditya S. Khair
Keyword(s):  
Concentration Polarization ◽  
Normal Flow ◽  
Electrokinetic Instability

scholarly journals Investigation on the Stability of Random Vortices in an Ion Concentration Polarization Layer with Imposed Normal Fluid Flow

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 529
Author(s):  
Jihye Choi ◽  
Ali Mani ◽  
Hyomin Lee ◽  
Sung Jae Kim
Keyword(s):  
Fluid Flow ◽  
Space Charge ◽  
Concentration Polarization ◽  
Space Charge Layer ◽  
Ion Concentration ◽  
Maximum Point ◽  
Normal Flow ◽  
Normal Fluid ◽  
Charge Layer ◽  
Ion Concentration Polarization

While nanoscale electrokinetic studies based on ion concentration polarization has been actively researched recently, random vortices naturally occur, leading to significantly destabilize in laboratory experiments or practical applications. These random vortices agitate the fluid inside microchannels and let the sample molecules seriously leak out preventing them from being controlled. Therefore, several trials have been reported to regulate those uninvited fluctuations by fluid flow tangential to a nanoporous membrane. Indeed, the influence of normal flow should be studied since the mass transport happens in the normal direction to the membrane. Thus, in this work, the nonlinear influence of normal flow to the instability near ion-selective surface was investigated by fully-coupled direct numerical simulation using COMSOL Multiphysics. The investigation on the effect of normal flow revealed that a space charge layer plays a significant role in the onset and growth of instability. The normal flow from the reservoir into the ion-selective surface pushed the space charge layer and decreased the size of vortices. However, there existed a maximum point for the growth of instability. The squeeze of the space charge layer increased the gradient of ion concentration in the layer, which resulted in escalating the velocity of vortices. On the other hand, the normal flow from the ion-selective surface into the reservoir suppressed the instability by spreading ions in the expanding space charge layer, leading to the reduction of ion concentration delayed the onset of instability. These two different mechanisms rendered asymmetric transition of stability as a function of the Peclet number and applied voltage. Therefore, this investigation would help understand the growth of instability and control the inevitable random vortices for the inhibition of fluid-agitation and leakage.

Multi-vortical flow inducing electrokinetic instability in ion concentration polarization layer

Nanoscale ◽  
2012 ◽  
Vol 4 (23) ◽  
pp. 7406 ◽  
Author(s):  
Sung Jae Kim ◽  
Sung Hee Ko ◽  
Rhokyun Kwak ◽  
Jonathan D. Posner ◽  
Kwan Hyoung Kang ◽  
...  
Keyword(s):  
Concentration Polarization ◽  
Ion Concentration ◽  
Vortical Flow ◽  
Electrokinetic Instability ◽  
Ion Concentration Polarization ◽  
Concentration Polarization Layer

Effect of the membrane potential on the performance of ultrafiltration membranes

1986 ◽  
Vol 51 (3) ◽  
pp. 539-544 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Jaromír Lukáš ◽  
Jiří Vacík ◽  
Volker Gröbe
Keyword(s):  
Membrane Potential ◽  
Concentration Polarization ◽  
Ultrafiltration Membranes ◽  
Membrane Cleaning ◽  
Gel Layer ◽  
Charged Membrane ◽  
Protein Molecules ◽  
Polysulfone Membranes ◽  
Pressure Driven

In the pressure driven process the performance of membranes for ultrafiltration can be changed by incorporating charged groups into the membranes. sulfonation of polysulfone membranes the membrane potential is varied. On interaction of the negatively charged membrane with positively or negatively charged protein molecules the formation of a concentration polarization gel layer proceeds at different rate. Thus, the performance of the membrane can be controlled by the membrane potential. The dependence of the performance on the potential is discussed and procedures for membrane cleaning are suggested.

Concentration polarization formation in ultrafiltration of blood and plasma

1993 ◽  
Vol 84 (3) ◽  
pp. 293-301 ◽  
Author(s):  
L Ding
Keyword(s):  
Concentration Polarization

Enhancement of concentration polarization due to gel accumulated at membrane surface

2006 ◽  
Vol 285 (1-2) ◽  
pp. 96-101 ◽  
Author(s):  
Sergey P. Agashichev
Keyword(s):  
Concentration Polarization ◽  
Membrane Surface

CFD simulation of air-sparged slug flow in the flat-sheet membrane: A concentration polarization study

2021 ◽  
Vol 270 ◽  
pp. 118816
Author(s):  
Ahmad Golrokh Sani ◽  
Hamidreza Najafi ◽  
Seyedeh Shakiba Azimi
Keyword(s):  
Slug Flow ◽  
Concentration Polarization ◽  
Cfd Simulation ◽  
Flat Sheet ◽  
Polarization Study ◽  
Flat Sheet Membrane ◽  
Sheet Membrane
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