Salt concentration dependence of ionic conductivity in ion exchange membranes

Kamcev, Jovan; Sujanani, Rahul; Jang, Eui Soung; Yan, Ni; Moe, Neil E.; Paul, Donald R; Freeman, Benny D.

doi:10.1016/j.memsci.2017.10.024

Cited by 141 publications

(117 citation statements)

References 56 publications

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“…To aid visual interpretation, the data points are interconnected by solid lines for experiments performed with alternating current (AC) and dotted lines for experiments performed with direct current (DC). An exception is the dashed lines in the CMX and AMX plots from the experiments of Kamcev et al [21], who used a short dip with the membranes in concentrated NaCl (5 M) before the measurement to prevent depletion layers between the electrodes and the membrane. Apart from these two datasets, the membrane resistance increased at lower concentrations in all cases of these five selected membranes.…”

Section: Resultsmentioning

confidence: 99%

“…Comparisons between AC and DC methods for measuring membrane resistance and general comparisons between different measurement techniques are discussed by Galama et al [1,20], Karpenko et al [22], Kamcev et al [21], Nouri et al [15], and Zabolotsky et al [40].…”

Section: Model Equation Parametersmentioning

confidence: 99%

“…In most cases, membranes are equilibrated some hours in the bulk solution before measurement. One exception is the experiments by Kamcev et al, where membranes were dipped briefly in a 5 M NaCl solution to improve the contact (and expel an adjacent water layer) between the metal electrodes and the membrane [21]. Another example of different conditioning techniques is reported by Berezina et al [34].…”

mentioning

confidence: 99%

“…With alternating current superimposed on a direct current, the pure membrane resistance can be found at real operating conditions presumed that the fluid velocity and current density are the same in the both cases. Kamcev et al used this combination [21]. However, they used different ratios DC/AC throughout their measurements.…”

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confidence: 99%

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The Effect of the NaCl Bulk Concentration on the Resistance of Ion Exchange Membranes—Measuring and Modeling

Veerman¹

2020

Energies

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Ion exchange membranes are used in different fields of energy and separation technology such as electrodialysis, reverse electrodialysis, and fuel cells. Important aspects are permselectivity, resistance, and water transport. In this paper, we focus on the effect of the bulk NaCl concentration on the membrane resistance. Data from 36 publications containing 145 datasets using 6 different methods for measuring membrane resistance were compared. This study showed that the membrane resistance is dependent on the method of measuring. Two probable causes are identified: the application of reference electrodes and the presence of direct electrode-membrane contact. In addition, three physical and three phenomenological membrane models were tested by fitting these to the datasets. First, fits in the resistance domain were compared with fits in the conductivity domain. Resistance fits are sensitive to fluctuations in low concentrations, whereas fits in the conductivity domain are subject to nonlinear responses at high concentration. Resistance fits resulted in higher coefficients of determination (R 2 ). Then, the six models were compared. The 1-thread model with two fit parameters was in almost all cases a good start. More improvements were difficult to test due to the restricted number of data points in most of the used publications, although this study shows that the so-called Gierke model (with 4 parameters) fits better than the 3-thread model. Phenomenological models were also tested, but they did not lead to much better fits.

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Section: Resultsmentioning

confidence: 99%

Section: Model Equation Parametersmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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The Effect of the NaCl Bulk Concentration on the Resistance of Ion Exchange Membranes—Measuring and Modeling

Veerman¹

2020

Energies

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“…For the given design, elevating the feeding concentrations of reactants will increase the reactant concentrations in the catalyst layer, which is called local concentrations. Within a certain increase range, the anodic reaction kinetics will be enhanced due to the increase of local reactant concentrations, the internal resistance will be lowered as the increase of ionic conductivity of the membrane, and the energy capacity will be increased due to an increase of the fuel amount. However, the previous investigations on liquid fuel cells have demonstrated that too high concentration will lead to some drawbacks due to (1) species crossover, meaning that formate and alkali can pass through the membrane and reach the cathode, resulting in the mixed potential and a waste of species, as well as lowering the cathodic kinetics; (2) competitive adsorption, meaning that when one reactant is excessive, the adsorption of the other on active sites will be limited; and (3) higher solution viscosity, increasing transport resistances of various reactants .…”

Section: Resultsmentioning

confidence: 99%

Performance characteristics of a passive direct formate fuel cell

Pan

2019

Int J Energy Res

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Summary A passive direct formate fuel cell using ambient air is designed, fabricated, and tested. This fuel cell does not use any auxiliary devices such as pumps, gas compressors, and gas blowers. The simple and compact structure well fits the need of portable applications. In this fuel cell, a solution having formate and alkali is anode fuel, while ambient oxygen is used as cathode oxidant, and a cation exchange membrane serves as an ionic conductor between two electrodes. Our performance tests have shown that a peak power density of 16.6 mW cm−2 as well as an open‐circuit voltage of 0.97 V are achieved by the present fuel cell at 60 °C, when running on anode fuel containing 5.0 M sodium formate and 3.0 M sodium hydroxide. This performance is even 31.7% higher than that achieved by an active direct formate fuel cell reported in the open literature (12.6 mW cm−2), which also uses a cation exchange membrane. The effects of the operating parameters are also investigated, including the concentrations of fuel and alkali as well as the operating temperature. The fuel solution at low concentrations results in an inadequate local concentration of reactants, so that the anodic kinetics becomes sluggish. Although increasing the sodium hydroxide concentration enhances the anodic formate oxidation kinetics, too high concentration of sodium hydroxide leads to too many active sites being covered by hydroxide ions and thus adsorption and reaction of formate ions being limited. Moreover, too high concentration of sodium hydroxide or sodium formate also leads to the fuel solution being highly viscous, hindering the motion of various ions, as well as thus increasing both concentration loss and the ohmic loss. The compromise between benefits and the drawbacks of using high‐concentration reactants results in an optimal composition of the fuel solution, which contains 5.0 M sodium formate and 3.0 M sodium hydroxide. Furthermore, the present fuel cell delivers a voltage around 0.6 V for 20 hours at 4.0 mA cm−2.

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Ion‐Conducting Hydrogels and Their Applications in Bioelectronics

Dechiraju

Jia

Luo

et al. 2021

Advanced Sustainable Systems

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Bioelectronics focuses on the interface between biological systems and electronics. Most biological systems are soft and wet, while electronics are typically hard and dry. Information in the form of charge is carried by electrons and holes in electronics, while ions and charged molecules are the charge carriers in biological systems. As such, finding the right material for the bioelectronic interface is challenging. Hydrogels are water swollen porous polymer networks and, similarly to biological systems, hydrogels are wet, soft, and ion conducting. These properties make hydrogels an ideal choice for the bioelectronic interface between electronics and biological systems. This review focuses on polyelectrolyte hydrogels, a class of hydrogels that has fixed charges as part of the polymer network. In order to maintain charge neutrality, these charges attract mobile ions of the opposite charge in the water swollen pores. These mobile ions give the hydrogels selective ionic conductivity. Here, it is discussed brief fundamentals of hydrogels, ionic conduction mechanism and optimization of the conductivity, and applications in bioelectronic sensors and mechanical actuators.

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Salt concentration dependence of ionic conductivity in ion exchange membranes

Cited by 141 publications

References 56 publications

The Effect of the NaCl Bulk Concentration on the Resistance of Ion Exchange Membranes—Measuring and Modeling

The Effect of the NaCl Bulk Concentration on the Resistance of Ion Exchange Membranes—Measuring and Modeling

Performance characteristics of a passive direct formate fuel cell

Ion‐Conducting Hydrogels and Their Applications in Bioelectronics

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