scholarly journals Mathematical Modeling of the Phenomenon of Space-Charge Breakdown in the Galvanostatic Mode in the Section of the Electromembrane Desalination Channel

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 873
Author(s):  
Aminat Uzdenova ◽  
Makhamet Urtenov
Keyword(s):  
Space Charge ◽  
Onset Time ◽  
Membrane System ◽  
Anion Exchange Membranes ◽  
Ion Transfer ◽  
Membrane Systems ◽  
One Dimensional ◽  
Galvanostatic Mode ◽  
Extended Space ◽  
Electric Mode

One of the ways to increase the efficiency of the desalination process in membrane systems is to use intensive current modes. Recently, the phenomenon of space-charge breakdown was theoretically described for desalination under intensive current modes. The space-charge breakdown is a decrease in the magnitude and size of the extended space charge regions (SCRs) of opposite signs, formed at the cation- and anion-exchange membranes in the desalination channel, when they approach each other. Therefore, this phenomenon negatively affects the intensity of electroconvection and the efficiency of mass transfer in membrane systems. We report the results of the first theoretical analysis of the space-charge breakdown in the galvanostatic electric mode, which is generally used in the research and operation of membrane systems. For this purpose, a one-dimensional model of the ion transfer of the electrolyte solution in the section of the desalination channel at the direct current is developed. The regularities of changes in the extended SCRs in the galvanostatic mode are determined. A relation is obtained for the onset time of the space-charge breakdown, which makes it possible to determine the parameters of the effective operation of the membrane system.

scholarly journals Stationary model of salt ion transfer in two-dimensional electrodialysis desalting channel in galvanostatic mode

2019 ◽  
Vol 18 (4) ◽  
pp. 426-437
Author(s):  
A. M. Uzdenova ◽  
M. Kh. Urtenov
Keyword(s):  
Mathematical Model ◽  
Space Charge ◽  
Membrane System ◽  
Physicochemical Characteristics ◽  
Ion Transfer ◽  
Two Dimensional ◽  
Membrane Systems ◽  
Galvanostatic Mode ◽  
Salt Ions ◽  
Study Results

Introduction.The theoretical description of the ion transport in membrane systems in the galvanostatic mode is presented. A desalting channel of the electrodialysis apparatus is considered as a membrane system. The work objectives are the development and verification of a two-dimensional mathematical model of the stationary transport of salt ions in the desalting channel of the electrodialysis apparatus for the galvanostatic mode.Materials and Methods.A new model of ion transfer is proposed. It is based on the Nernst –Planck – Poisson equations for the electric potential and on the equation for the electric current stream function. A numerical solution to the boundary value model problem by the finite element method is obtained using the Comsol Multiphysics software package.Research Results.The developed mathematical model enables to describe the stationary transfer of binary salt ions in the desalting channel of the electrodialysis apparatus. Herewith, the violation of the solution electroneutrality and the formation of the dilated domain of space charge at overlimiting currents in the galvanostatic mode are considered. A good agreement between the physicochemical characteristics of the transfer calculated by the models for the galvanostatic and potentiostatic modes implies adequacy of the constructed model.Discussion and Conclusions.The developed model can interpret the experimental study results of ion transfer in membrane systems if this process takes place in the galvanostatic mode. Some electrokinetic processes are associated with the appearance of a dilated domain of space charge at overlimiting currents. When describing the formation of this domain, it is possible to find out how the processes dependent on it affect the ion transfer in the galvanostatic mode.

In situ construction of interconnected ion transfer channels in anion-exchange membranes for fuel cell application

2017 ◽  
Vol 5 (8) ◽  
pp. 4003-4010 ◽  
Author(s):  
Jiangju Si ◽  
Haining Wang ◽  
Shanfu Lu ◽  
Xin Xu ◽  
Sikan Peng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Anion Exchange ◽  
Anion Exchange Membranes ◽  
Ion Transfer ◽  
Trade Off ◽  
Fuel Cell Application ◽  
Transfer Channels

By modulating the amphiphilic architectures, 3D well-connected nano-channels are constructed and a trade-off between conductivity and stability in AEMs is achieved.

Electro-osmotic slip and electroconvective instability

2007 ◽  
Vol 579 ◽  
pp. 173-226 ◽  
Author(s):  
B. ZALTZMAN ◽  
I. RUBINSTEIN
Keyword(s):  
Space Charge ◽  
Double Layer ◽  
Electric Double Layer ◽  
Equilibrium Structure ◽  
Stability Study ◽  
Quasi Equilibrium ◽  
Electric Conduction ◽  
Extended Space ◽  
Sequence Of Events ◽  
Non Equilibrium

Electric conduction from an electrolyte solution into a charge selective solid, such as ion exchange membrane or electrode, becomes unstable when the electrolyte concentration near the interface approaches zero owing to diffusion limitation. The sequence of events leading to instability is as follows: upon the decrease of the interface concentration, the electric double layer at the interface transforms from its common quasi-equilibrium structure to a different, non-equilibrium one. The key feature of this new structure is an extended space charge added to the usual one of the quasi-equilibrium electric double layer. The non-equilibrium electro-osmotic slip related to this extended space charge renders the quiescent conductance unstable. A unified asymptotic picture of the electric double-layer undercurrent, encompassing all regimes from quasi-equilibrium to the extreme non-equilibrium one, is developed and employed for derivation of a universal electro-osmotic slip formula. This formula is used for a linear stability study of quiescent electric conduction, yielding the precise parameter range of instability, compared with that in the full electroconvective formulation. The physical mechanism of instability is traced both kinematically, in terms of non-equilibrium electro-osmotic slip, and dynamically, in terms of forces acting in the electric double layer.

The polypeptides of rat liver nuclear envelope. II. Comparison of rat liver nuclear membrane polypeptides with those of the rough endoplasmic reticulum

1980 ◽  
Vol 43 (1) ◽  
pp. 269-277
Author(s):  
J.C. Richardson ◽  
A.H. Maddy
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Relative Proportion ◽  
Membrane System ◽  
Membrane Systems ◽  
Nuclear Membranes ◽  
Cytoplasmic Surface ◽  
Triton X

Nuclear envelopes are separated into pore-lamina and membrane sub-fractions by extraction in 2.0% Triton X-100 followed by pelleting of the pore-laminae. The polypeptides of these subfractions are then compared with those from isolated rough endoplasmic reticulum. The dispositions of individual polypeptides in the cytoplasmic surface of nuclear envelopes and rought endoplasmic reticulum were studied by lactoperoxidase-catalysed iodination. These studies show that although the nuclear membranes exhibit several homologies with the Triton-soluble polypeptides of the rough endoplasmic reticulum the relative proportion of individual polypeptides within the two systems are very largely different. The cytoplasmic surfaces of the 2 membrane systems show only 2 obvious homologies at 105 000 and 15 000 mol. wt and the overall impression is that, at least in rat liver, the outer nuclear membrane is very substantially differentiated from rough endoplasmic reticulum. It is concluded that the nuclear membranes may not be regarded as a mere continuum of the endoplasmic reticulum, but should be seen as a highly specialized membrane system in their own right.

Oxygen evolution sensitized by tin porphyrin in microheterogeneous system and membrane systems

2003 ◽  
Vol 07 (01) ◽  
pp. 37-41 ◽  
Author(s):  
Sheng Wang ◽  
Teruo Hori
Keyword(s):  
Visible Light ◽  
Oxygen Evolution ◽  
Visible Light Irradiation ◽  
Membrane System ◽  
Conventional System ◽  
Membrane Systems ◽  
Sem Images ◽  
Tin Porphyrin ◽  
Pvc Membranes ◽  
Evolution Systems

Tin porphyrin ( SnTPP ) was applied to two new types of photoinduced oxygen evolution systems by visible light irradiation. In microheterogeneous system, tin porphyrin was dispersed by a nonionic surfactant and the system could efficiently oxidize water to evolve oxygen when compared with the conventional system. In addition, two types of tin porphyrin fixed PVC membranes, porous and homogeneous, were prepared and applied to a photoinduced oxygen evolution membrane system. SEM images of two types of tin porphyrin fixed PVC membranes also show differences in both morphologies.

Sign in / Sign up

Export Citation Format

Share Document