Transition to electrokinetic instability near imperfect charge-selective membranes

2018 ◽  
Vol 30 (8) ◽  
pp. 082006 ◽  
Author(s):  
E. A. Demekhin ◽  
G. S. Ganchenko ◽  
E. N. Kalaydin
Keyword(s):  
Electrokinetic Instability ◽  
Selective Membranes

scholarly journals Transitions and Instabilities in Imperfect Ion-Selective Membranes

2020 ◽  
Vol 21 (18) ◽  
pp. 6526
Author(s):  
Jarrod Schiffbauer ◽  
Evgeny Demekhin ◽  
Georgy Ganchenko
Keyword(s):  
Electrolyte Solutions ◽  
Darcy Number ◽  
Porous Membrane ◽  
Quiescent State ◽  
System Of Equations ◽  
High Concentration ◽  
Electrokinetic Instability ◽  
The One ◽  
Overlimiting Current ◽  
Selective Membranes

Numerical investigation of the underlimiting, limiting, and overlimiting current modes and their transitions in imperfect ion-selective membranes with fluid flow through permitted through the membrane is presented. The system is treated as a three layer composite system of electrolyte-porous membrane-electrolyte where the Nernst–Planck–Poisson–Stokes system of equations is used in the electrolyte, and the Darcy–Brinkman approach is employed in the nanoporous membrane. In order to resolve thin Debye and Darcy layers, quasi-spectral methods are applied using Chebyshev polynomials for their accumulation of zeros and, hence, best resolution in the layers. The boundary between underlimiting and overlimiting current regimes is subject of linear stability analysis, where the transition to overlimiting current is assumed due to the electrokinetic instability of the one-dimensional quiescent state. However, the well-developed overlimiting current is inherently a problem of nonlinear stability and is subject of the direct numerical simulation of the full system of equations. Both high and low fixed charge density membranes (low- and high concentration electrolyte solutions), acting respectively as (nearly) perfect or imperfect membranes, are considered. The perfect membrane is adequately described by a one-layer model while the imperfect membrane has a more sophisticated response. In particular, the direct transition from underlimiting to overlimiting currents, bypassing the limiting currents, is found to be possible for imperfect membranes (high-concentration electrolyte). The transition to the overlimiting currents for the low-concentration electrolyte solutions is monotonic, while for the high-concentration solutions it is oscillatory. Despite the fact that velocities in the porous membrane are much smaller than in the electrolyte region, it is further demonstrated that they can dramatically influence the nature and transition to the overlimiting regimes. A map of the bifurcations, transitions, and regimes is constructed in coordinates of the fixed membrane charge and the Darcy number.

Thermoelectric Response of Ion‐Selective Membranes: Modelling and Experimental Studies

2021 ◽  
Vol 8 (3) ◽  
pp. 585-591
Author(s):  
Rongjie Yang ◽  
Shanshan Liu ◽  
Lin Zhou ◽  
Xingyu Lin ◽  
Bin Su
Keyword(s):  
Experimental Studies ◽  
Selective Membranes

Designing Ion‐Selective Membranes for Vanadium Redox Flow Batteries

2021 ◽  
pp. 2001308
Author(s):  
Hamid Amiri ◽  
Mohsen Khosravi ◽  
Mojtaba Ejeian ◽  
Amir Razmjou
Keyword(s):  
Redox Flow Batteries ◽  
Flow Batteries ◽  
Vanadium Redox ◽  
Selective Membranes

Hierarchical selective membranes combining carbonaceous nanoparticles and commercial permeable substrates for oil/water separation

2020 ◽  
Vol 234 ◽  
pp. 116053 ◽  
Author(s):  
Federico Trupp ◽  
Nicolás Torasso ◽  
Diana Grondona ◽  
Gerardo H. Rubiolo ◽  
Silvia Goyanes
Keyword(s):  
Water Separation ◽  
Oil Water Separation ◽  
Oil Water ◽  
Selective Membranes
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