Electrochemical impedance spectroscopy fingerprints the ion selectivity of microgel functionalized ion-exchange membranes

Roghmans, Florian; Martí-Calatayud, M.C.; Abdu, Said; Femmer, Robert; Tiwari, Rahul; Walther, Andreas; Weßling, Matthias

doi:10.1016/j.elecom.2016.09.009

Cited by 25 publications

(18 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the recent past, we have presented confluent monolayers of P2VP microgels coated on Nafion membranes via inclined plane self‐assembly to investigate the influence of the microgels on the ohmic resistance. In case of these homogeneously covered membranes, the ohmic resistance only increases about 6% compared to a bare membrane.…”

Section: Resultsmentioning

confidence: 99%

“…All chemicals were purchased from Sigma‐Aldrich. P2VP microgels were synthesized via surfactant free emulsion polymerization with a crosslinking degree of 1:100. Absorbed on a surface, the microgels have a thickness of 300 nm in swollen state.…”

Section: Methodsmentioning

confidence: 99%

“…The potential of microgels to influence ion transport in electrochemical deionization processes is relevant as well. Their effect on monovalent ion selectivity was investigated in our recent paper . Moreover, their ability to exhibit distinct properties under the effect of external stimuli opens a variety of possibilities to reversibly tune ion transport according to the needs of a specific electro‐membrane process.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

Roghmans

Evdochenko

Stockmeier

et al. 2018

Adv Materials Inter

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

Roghmans

Evdochenko

Stockmeier

et al. 2018

Adv Materials Inter

View full text Add to dashboard Cite

show abstract

“…The limiting current densities of an IEMelectrolyte system (Figure 1 (a)) should be determined first for appropriate ED experimental conditions in the selectivity measurements, because other complicating phenomena set in when the current density is above the limiting value [28,35] and these phenomena will alter the ion selectivity [5]. Figure 2 shows illustratively a sixcompartment cell used for the polarization I-V curve determination [10,35], as well as for the selectivity measurement [34,36]. The anode is a mixed-metal-oxide coated titanium mesh, and the cathode is a stainless steel plate.…”

Section: Ion Selectivity Measurements By Electrodialysismentioning

confidence: 99%

Ion mobility and partition determine the counter-ion selectivity of ion exchange membranes

Luo

Roghmans

Weßling

2020

Journal of Membrane Science

View full text Add to dashboard Cite

Ion (perm)selectivity and conductivity are the two most essential properties of an ion exchange membrane, yet no quantitative relation between them has been suggested. In this work, the selectivity between two different counter-ions is correlated to the membrane conductivity. We show that the counter-ion selectivity measured by conventional electrodialysis (ED) can be expressed by the product of two parameters: (a) the mobility ratio between these two different counter-ions in the membrane and (b) their partition coefficient between the solution and the membrane. This is reminiscent of the classical solution-diffusion model. Via the counter-ion mobility in the membrane, the selectivity could be simply expressed with the membrane conductivity and dimensional swelling degree at pure counter-ion forms and at mixed counter-ion form when the membrane has been equilibrated with 1:1 equivalence ratio of the two counter-ions in the solution. This correlation is validated experimentally for the ion selectivity of K + /Na + in two commercial hydrocarbon-based cation exchange membranes (CEMs). For K + /Na + in a commercial perfluorosulfonic CEM, and for Mg 2+ /Na + in all the three types of CEMs, the correlation could predict the counter-ion partition very well; but there is an underestimation of the K + /Na + and Mg 2+ /Na + mobility ratios afforded by this correlation, which might be due to simplification of the cation activity coefficients in CEMs. This work offers a convenient method to decouple experimentally the effect of partition and mobility in controlling the membrane selectivity, and also proposes a new perspective to study the selectivity as well as conductivity of ion exchange membranes.

show abstract

“…An additional high-frequency capacitive arc is obtained only for the nanocone membranes, and is attributable to the concentration polarization effects at the PA NI-sPPO interface (PSI). [19] Thec hange in pore size from the surface of the PA NI layer to the PSI is correlated by constant phase elements (Q)w here the Q index (n), which hereby varies between 0-1 (0 < n < 1) is inversely related to the membrane surface roughness/pore size. [20] As mall value of n EDLs (0.372) and large n PSI (0.894) is indicative of ad ecreasing pore diameter from the PA NI surface to the interior PSI (open nanopores at the (P 12 ) NCM surface support-ed by the nanoporous sponge,F igure 2).…”

Section: Angewandte Chemiementioning

confidence: 99%

Biomimetic Nanocones that Enable High Ion Permselectivity

et al. 2019

View full text Add to dashboard Cite

Artificial counterparts of conical-shaped transmembrane protein channelsa re of interest in biomedical sciences for biomolecule detection and selective ion permeation based on ionic sizea nd/or charge differences.H owever,i ndustrialscale applications such as seawater desalination, separation of mono-from divalent cations,a nd treatment of highly-saline industrial waste effluents are still big challenges for such biomimetic channels.Asimple monomer seeding experimental approach is used to grow ionically conductive biomimetic charged nanocone pores at the surface of an acid-functionalized membrane.T hese readily scalable nanocone membranes enable ultra-fast cation permeation (Na + = 8.4 vs.M g 2+ = 1.4 )a nd high ion charge selectivity (Na + /Mg 2+ = 6 )c ompared to the commercial state-of-the-art permselective membrane (CSO,S elemion, Japan) owingt on egligible surface resistance and positively charged conical pore walls.

show abstract

Electrochemical impedance spectroscopy fingerprints the ion selectivity of microgel functionalized ion-exchange membranes

Cited by 25 publications

References 31 publications

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

2D Patterned Ion‐Exchange Membranes Induce Electroconvection

Ion mobility and partition determine the counter-ion selectivity of ion exchange membranes

Biomimetic Nanocones that Enable High Ion Permselectivity

Contact Info

Product

Resources

About