Impact of ion exchange membrane surface charge and hydrophobicity on electroconvection at underlimiting and overlimiting currents

Nebavskaya, K. A.; Сарапулова, В. В.; Sabbatovskiy, Konstantin G; Соболев, В. Д.; Pismenskaya, Natalia; Sistat, Philippe; Cretin, Marc; Nikonenko, Victor

doi:10.1016/j.memsci.2016.09.038

Cited by 81 publications

(52 citation statements)

References 66 publications

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“…Nanometer‐thick micrometer‐sized polyelectrolyte patterns transferred through microcontact printing on top of a membrane have the same effect on the emergence of electroosmotic induced fluid instabilities . Other works have shown that also hydrophobic surfaces lead to an intensified evolution of electroconvective vortices mixing the diffusion boundary layer . Through direct numerical simulations, we have recently discovered a complex chaotic mixing behavior induced by impermeable patches .…”

Section: Introductionmentioning

confidence: 77%

“…A drawback of the Sand equation is that it only takes the diffusive ion transport into account. It was already mathematically and experimentally shown that experimentally determined transition times are always larger than the ones obtained by the Sand equation . Thus, electroconvective flows may already promote the ion transfer even before the membrane surface is fully depleted.…”

Section: Methodsmentioning

confidence: 93%

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2D Patterned Ion‐Exchange Membranes Induce Electroconvection

Roghmans

Evdochenko

Stockmeier

et al. 2018

Adv Materials Inter

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Concentration polarization is a diffusion‐limited phenomenon for ion transport in electrodialysis based desalination processes. Once a so‐called limiting current is reached, the resistance of the system rises notably manifested as a plateau region in the current–voltage curves. For long it is hypothesized that altering the surface properties of the membrane can overcome the diffusional transport limitation by the induction of electroconvective vortices mixing the laminar boundary layer. To systematically investigate the influence of geometrical and chemical membrane surface topology on the evolution of electroconvection, circular patterns of polystyrene, poly(2‐vinylpyridine) (P2VP), and P2VP microgels are inkjet printed on cation‐exchange membranes. All types of patterns cause an insignificant increase in membrane resistance but they reduce the plateau lengths indicating the desired accelerated onset of electroconvection. In case of polystyrene (PS) patterns, the drop in plateau length results in a small reduction in transport resistance for overlimiting currents. However, membranes modified with linear P2VP and P2VP microgel patterns do exhibit a significantly decreased resistance in this region at a simultaneous increase of the limiting current density. Direct numerical simulations support the interpretation that the surface charge of the printed patterns influences the direction of the vortices being advantageous during ion transport toward the membrane.

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Section: Introductionmentioning

confidence: 77%

Section: Methodsmentioning

confidence: 93%

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

Roghmans

Evdochenko

Stockmeier

et al. 2018

Adv Materials Inter

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“…The properties of the IEM surface, which affect the EC intensity and the rate of H + and OHion generation, include the electrical and geometric heterogeneity of the surface [12], the degree of its hydrophobicity/hydrophilicity [12], and the surface charge [23]. The membrane bulk properties do not influence electroconvection.…”

Section: Introductionmentioning

confidence: 99%

How Electrical Heterogeneity Parameters of Ion-Exchange Membrane Surface Affect the Mass Transfer and Water Splitting Rate in Electrodialysis

Zyryanova

Mareev

Gil

et al. 2020

IJMS

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Electrodialysis (ED) has been demonstrated as an effective membrane method for desalination, concentration, and separation. Electroconvection (EC) is a phenomenon which can essentially increase the mass transfer rate and reduce the undesirable water splitting effect. Efforts by a number of researchers are ongoing to create conditions for developing EC, in particular, through the formation of electrical heterogeneity on the membrane surface. We attempt, for the first time, to optimize the parameters of surface electrical heterogeneity for ion-exchange membranes used in a laboratory ED cell. Thirteen different patterns on the surface of two Neosepta anion-exchange membranes, AMX and AMX-Sb, were tested. Low-conductive fluoropolymer spots were formed on the membrane surface using the electrospinning technique. Spots in the form of squares, rectangles, and circles with different sizes and distances between them were applied. We found that the spots’ shape did not have a visible effect. The best effect, i.e., the maximum mass transfer rate and the minimum water splitting rate, was found when the spots’ size was close to that of the diffusion layer thickness, δ (about 250 μm in the experimental conditions), and the distance between the spots was slightly larger than δ, such that the fraction of the screened surface was about 20%.

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“…Introducing ion-conducting and topographic heterogeneity on the membranes' surface is the most investigated method for enhancing electroconvection [11,12]. In addition to membrane surface properties, the type of electrolyte has been also demonstrated to be an influencing parameter in the early onset and intensification of electroconvection.…”

Section: Introductionmentioning

confidence: 99%

Mass Transfer Phenomena during Electrodialysis of Multivalent Ions: Chemical Equilibria and Overlimiting Currents

2018

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Electrodialysis is utilized for the deionization of saline streams, usually formed by strong electrolytes. Recently, interest in new applications involving the transport of weak electrolytes through ion-exchange membranes has increased. Clear examples of such applications are the recovery of valuable metal ions from industrial effluents, such as electronic wastes or mining industries. Weak electrolytes give rise to a variety of ions with different valence, charge sign and transport properties. Moreover, development of concentration polarization under the application of an electric field promotes changes in the chemical equilibrium, thus making more complex understanding of mass transfer phenomena in such systems. This investigation presents a set of experiments conducted with salts of multivalent metals with the aim to provide better understanding on the involved mass transfer phenomena. Chronopotentiometric experiments and current-voltage characteristics confirm that shifts in chemical equilibria can take place simultaneous to the activation of overlimiting mass transfer mechanisms, that is, electroconvection and water dissociation. Electroconvection has been proven to affect the type of precipitates formed at the membrane surface thus suppressing the simultaneous dissociation of water. For some electrolytes, shifts in the chemical equilibria forced by an imposed electric field generate new charge carriers at specific current regimes, thus reducing the system resistance.

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Impact of ion exchange membrane surface charge and hydrophobicity on electroconvection at underlimiting and overlimiting currents

Cited by 81 publications

References 66 publications

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

How Electrical Heterogeneity Parameters of Ion-Exchange Membrane Surface Affect the Mass Transfer and Water Splitting Rate in Electrodialysis

Mass Transfer Phenomena during Electrodialysis of Multivalent Ions: Chemical Equilibria and Overlimiting Currents

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