Influence of the convective term in the Nernst-Planck equation on properties of ion transport through a layer of solution or membrane

Nikonenko, Victor; Лебедев, К. А.; Suleimanov, Sh. Sh.

doi:10.1134/s1023193509020062

Cited by 12 publications

(5 citation statements)

References 20 publications

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“…Therefore, no limited diffusion regime is established for any of the ionic species involved in the MA electrochemical reactions. The ionic flux through a nanoporous membrane of porosity P and thickness L is given by the extended Nernst–Planck equation for the ionic transport (eq ). − where x represents the distance to the reaction interface, that is, to the pore bottom, D is the diffusion coefficient of the specific ion of interest, and C ( x ) corresponds to its concentration and z to its charge number. R and F are ideal gas and Faraday constants, respectively, V ( x ) is the electric potential inside the pores and υ eo is the solution velocity due to convection.…”

Section: Results and Discussionmentioning

confidence: 99%

Unveiling the Hard Anodization Regime of Aluminum: Insight into Nanopores Self-Organization and Growth Mechanism

Vega

Garcı́a

Montero-Moreno

et al. 2015

ACS Appl. Mater. Interfaces

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Pores growth mechanism and their self-ordering conditions are investigated for nanoporous alumina membranes synthesized by hard anodization (HA) of Al in a broad range of anodic conditions, covering oxalic acid electrolytes with concentrations from 0.300 M down to 0.075 M and potentiostatic anodization voltages between 120 and 225 V. The use of linear sweep voltammetry (LSV) and scanning and transmission electron microscopy, together with image analysis techniques allow one to characterize the intrinsic nature of the HA regime. HA of aluminum is explained on the basis of a phenomenological model taking into account the role of oxalate ions and their limited diffusion through alumina nanochannels from a bulk electrolyte. The depletion of oxalate ions at the bottom of the pores causes an increased growth of the alumina barrier layer at the oxide/electrolyte interface. Furthermore, an innovative method has been developed for the determination of the HA conditions leading to self-ordered pore growth in any given electrolyte, thus allowing one to extend the available range of interpore distances of the highly ordered hexagonal pore arrangement in a wide range of 240-507 nm, while keeping small pore diameters of 50-60 nm.

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Section: Results and Discussionmentioning

confidence: 99%

Unveiling the Hard Anodization Regime of Aluminum: Insight into Nanopores Self-Organization and Growth Mechanism

Vega

Garcı́a

Montero-Moreno

et al. 2015

ACS Appl. Mater. Interfaces

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“…The theoretical modeling of CBLs creation/destruction (concentration polarization phenomenon) is based, among others, on the Nernst–Planck, Poisson, Stokes, Fick, and/or Kedem–Katchalsky [5, 7, 9–12, 28–32] equations. To describe the concentration polarization of a system, we introduce the relative permeability coefficient ( ζ s ) for a system consisting of membrane and concentration boundary layers [1], also called the diffusive Katchalsky factor [33, 34] and propose the model equation for this coefficient and its dependence on different parameters [2].…”

Section: Introductionmentioning

confidence: 99%

Laser interferometric investigation of solute transport through membrane-concentration boundary layer system

et al. 2015

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We investigate diffusive transport in a membrane system with a horizontally mounted membrane under concentration polarization conditions performed by a laser interferometry method. The data obtained from two different theoretical models are compared to the experimental results of the substance flux. In the first model, the membrane is considered as infinitely thin, while in the second one as a wall of finite thickness. The theoretical calculations show sufficient correspondence with the experimental results. On the basis of interferometric measurements, the relative permeability coefficient (ζs) for the system, consisting of the membrane and concentration boundary layers, was also obtained. This coefficient reflects the concentration polarization of the membrane system. The obtained results indicate that the coefficient ζs of the membrane-concentration boundary layer system decreases in time and seems to be independent of the initial concentration of the solute.

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“…For the oxidation reaction to proceed at a steady state, OH – ions have to be transported from the cathode to the anode through the membrane. A limiting current can arise when OH – ions are consumed at the anode faster than they are transported through the membrane. , When the anolyte concentration was increased to 2.0 M KOH (0.5 M KOH catholyte) to provide an osmotic pressure to drive water from the catholyte to compensate for the electro-osmotic flow, the overpotential using the TFC-no PET was reduced from 0.48 V (0.5 M KOH anolyte and 0.5 M KOH catholyte) to 0.32 V (Figure ). The overpotential using the AEM was also changed, but only slightly by using the same concentrations of KOH (0.5 M) in both chambers (0.38 V) compared to a slightly lower overpotential using the 2 M anolyte (0.32 V) at the same current condition of 100 mA/cm 2 (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Thin-Film Composite Membranes for Hydrogen Evolution with a Saline Catholyte Water Feed

Shi,

Zhou,

Taylor

et al. 2024

Environ. Sci. Technol.

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Hydrogen gas evolution using an impure or saline water feed is a promising strategy to reduce overall energy consumption and investment costs for on-site, large-scale production using renewable energy sources. The chlorine evolution reaction is one of the biggest concerns in hydrogen evolution with impure water feeds. The "alkaline design criterion" in impure water electrolysis was examined here because water oxidation catalysts can exhibit a larger kinetic overpotential without interfering chlorine chemistry under alkaline conditions. Here, we demonstrated that relatively inexpensive thin-film composite (TFC) membranes, currently used for high-pressure reverse osmosis (RO) desalination applications, can have much higher rejection of Cl − (total crossover of 2.9 ± 0.9 mmol) than an anion-exchange membrane (AEM) (51.8 ± 2.3 mmol) with electrolytes of 0.5 M KOH for the anolyte and 0.5 M NaCl for the catholyte with a constant current (100 mA/cm 2 for 20 h). The membrane resistances, which were similar for the TFC membrane and the AEM based on electrochemical impedance spectroscopy (EIS) and Ohm's law methods, could be further reduced by increasing the electrolyte concentration or removal of the structural polyester supporting layer (TFC-no PET). TFC membranes could enable pressurized gas production, as this membrane was demonstrated to be mechanically stable with no change in permeate flux at 35 bar. These results show that TFC membranes provide a novel pathway for producing green hydrogen with a saline water feed at elevated pressures compared to systems using AEMs or porous diaphragms.

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Influence of the convective term in the Nernst-Planck equation on properties of ion transport through a layer of solution or membrane

Cited by 12 publications

References 20 publications

Unveiling the Hard Anodization Regime of Aluminum: Insight into Nanopores Self-Organization and Growth Mechanism

Unveiling the Hard Anodization Regime of Aluminum: Insight into Nanopores Self-Organization and Growth Mechanism

Laser interferometric investigation of solute transport through membrane-concentration boundary layer system

Thin-Film Composite Membranes for Hydrogen Evolution with a Saline Catholyte Water Feed

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