Focused Electric Field-Induced Ion Transport: Experiments and Modeling

Semichaevsky, Andrey; Johnson, Harley T.; Low, Khiam How; Paul, Dibyadeep; Chandra, Abhijit; Bastawros, Ashraf F.

doi:10.1149/1.3496405

Cited by 1 publication

(5 citation statements)

References 19 publications

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“…The transfer coefficient is α c = 1 / 2 for the rate-limiting transfer of 1 out of n = 2 electrons. , The data in Figure e is quantitatively consistent with the theory, R s = R res + R F (red curve), with a fitted prefactor of K 0 = 2.8 A/m 2 (for molar c 0 ). The measured exchange current I 0 = 3.9 A/m 2 at c 0 = 0.5 M is close to I 0 = 9.7 A/m 2 from recent experiments with CuSO 4 at neutral pH (which is below I 0 in strong acids , ). We are thus able to attribute the remaining voltage V in eq , which exhibits OLC (eq ), to the glass frit.…”

Section: Resultssupporting

confidence: 85%

“…The measured exchange current I 0 = 3.9 A/m 2 at c 0 = 0.5M is close to I 0 = 9.7 A/m 2 from recent experiments with CuSO 4 at neutral pH 60 (which is below I 0 in strong acids 55,56 ). We are thus able to attribute the remaining voltage V in Eq.…”

Section: Series Resistancesupporting

confidence: 85%

“…The frit is separated from a copper disk anode by an electrolyte reservoir ( L 0 = 3 mm thick). The electrolyte is aqueous copper sulfate (CuSO 4 ), so the well-studied copper deposition/dissolution reaction − , Cu 2 + + 2 normale − ↔ Cu is favored at both electrodes. Concentrated 1 M aqueous CuSO 4 solution is prepared by dissolving copper sulfate in the distilled water, and more dilute solutions are obtained by adding distilled water.…”

Section: Methodsmentioning

confidence: 99%

Section: Experiments Apparatusmentioning

confidence: 99%

“…The frit is separated from a copper disk anode by an electrolyte reservoir (L 0 = 3 mm thick). The electrolyte is aqueous copper sulfate (CuSO 4 ), so the well-studied copper deposition/dissolution reaction, [55][56][57]60 Cu 2+ + 2e − ←→ Cu, The Nafion membrane serves as the cation-selective surface in Figure 1, triggering salt depletion in the glass frit. In principle, the copper cathode could play this role by itself, but inserting the membrane better mimics theoretical models 18 and possible applications to water treatment below.…”

Section: Experiments Apparatusmentioning

confidence: 99%

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Overlimiting Current and Shock Electrodialysis in Porous Media

et al. 2013

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Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electroosmotic flow also contribute to ionic flux. In this article, we report experimental evidence for surface-driven overlimiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with a 500 nm mean pore size) in an aqueous electrolyte (CuSO4 or AgNO3) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electroosmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM to 1.0 M) after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water (≈10 μM) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow, bordering a depleted region that extends more than 0.5 mm across the outlet. The results suggest the feasibility of shock electrodialysis as a new approach to water desalination and other electrochemical separations.

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Section: Resultssupporting

confidence: 85%

Section: Series Resistancesupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Section: Experiments Apparatusmentioning

confidence: 99%

“…The frit is separated from a copper disk anode by an electrolyte reservoir (L 0 = 3 mm thick). The electrolyte is aqueous copper sulfate (CuSO 4 ), so the well-studied copper deposition/dissolution reaction, [55][56][57]60 Cu 2+ + 2e − ←→ Cu, The Nafion membrane serves as the cation-selective surface in Figure 1, triggering salt depletion in the glass frit. In principle, the copper cathode could play this role by itself, but inserting the membrane better mimics theoretical models 18 and possible applications to water treatment below.…”

Section: Experiments Apparatusmentioning

confidence: 99%

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