Quantum Chemical Evidence of a Fundamental  Difference Between Hydrations and Ion  Exchange Selectivities of Sodium  and Potassium Ions on Carboxylic  and Sulfonic Acid Cation Exchangers

Солдатов, В. С.; Kosandrovich, E. G.; Bezyazychnaya, T. V.

doi:10.1134/s0022476620120070

Cited by 2 publications

(5 citation statements)

References 20 publications

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“…The nonexistence of a direct bond between a fixed sulfonate group and a sodium ion due to the strong hydration of the ion described by Soldatov et al [ 27 ] agrees with the ab initio calculations of Shaposhnik and E. V. Butyrskaya [ 28 ]. These researchers found structures in which the sodium ion is connected to the sulfonate group through two intermediate water molecules.…”

Section: Introductionsupporting

confidence: 71%

“…Soldatov et al [ 29 ] also performed ab initio calculations and arrived at roughly similar structures as Badessa and Shaposhnik [ 27 ]. In all these cases, the counter-ions are directly or indirectly bonded to the fixed groups.…”

Section: Introductionmentioning

confidence: 80%

“…It is striking that much research has been carried out on cation exchange resins and cation exchange membranes while significantly less work has been performed on anion exchange systems. Many efforts in the field have been performed to explain the structure of exchangers [ 23 , 24 , 25 , 26 , 27 ]. In this sense, these works performed ab initio calculations of systems of various monovalent and divalent cations together with fixed anions and determined the spatial structure of fragments around these ions.…”

Section: Introductionmentioning

confidence: 99%

“…In this sense, these works performed ab initio calculations of systems of various monovalent and divalent cations together with fixed anions and determined the spatial structure of fragments around these ions. Soldatov et al [ 27 ] reported calculations of the interactions between the counter-ions Na + and K + and the fixed groups of the carboxylate group (~COO − ) and the sulfonate group (~SO 3 − ).…”

Section: Introductionmentioning

confidence: 99%

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Resistance of Ion Exchange Membranes in Aqueous Mixtures of Monovalent and Divalent Ions and the Effect on Reverse Electrodialysis

Veerman¹,

Gómez‐Coma

Ortiz

et al. 2023

Membranes

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Salinity gradient energy has gained attention in recent years as a renewable energy source, especially employing reverse electrodialysis technology (RED), which is based on the role of ion exchange membranes. In this context, many efforts have been developed by researchers from all over the world to advance the knowledge of this green source of energy. However, the influence of divalent ions on the performance of the technology has not been deeply studied. Basically, divalent ions are responsible for an increased membrane resistance and, therefore, for a decrease in voltage. This work focuses on the estimation of the resistance of the RED membrane working with water flows containing divalent ions, both theoretically by combining the one-thread model with the Donnan exclusion theory for the gel phase, as well as the experimental evaluation with Fumatech membranes FAS-50, FKS-50, FAS-PET-75, and FKS-PET-75. Furthermore, simulated results have been compared to data recently reported with different membranes. Besides, the influence of membrane resistance on the overall performance of reverse electrodialysis technology is evaluated to understand the impact of divalent ions in energy generation. Results reflect a minor effect of sulfate on the gross power in comparison to the effect of calcium and magnesium ions. Thus, this work takes a step forward in the knowledge of reverse electrodialysis technology and the extraction of salinity gradient energy by advancing the influence of divalent ions on energy recovery.

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Section: Introductionsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Resistance of Ion Exchange Membranes in Aqueous Mixtures of Monovalent and Divalent Ions and the Effect on Reverse Electrodialysis

Veerman¹,

Gómez‐Coma

Ortiz

et al. 2023

Membranes

View full text Add to dashboard Cite

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“…Moreover, because in such a way, a part of the fixed charges is neutralized, also a decrease of the permselectivity is expected. Soldatov et al [ 49 ] and Shaposhnik and Butyrskaya [ 50 ] performed ab initio calculations on the structure around a sulfonate group and an adjacent sodium ion. These data show that both ions are connected to each other via water molecules by means of hydrogen bonds.…”

Section: Effects Of Multivalent Ions On Red Powermentioning

confidence: 99%

Concepts and Misconceptions Concerning the Influence of Divalent Ions on the Performance of Reverse Electrodialysis Using Natural Waters

Veerman¹

2023

Membranes

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Divalent ions have a negative effect on the obtained power and efficiency of the reverse electrodialysis (RED) process when using natural waters. These effects can largely be attributed to the interaction between the various ions and the membranes, resulting in a decreased membrane voltage, an increased membrane resistance, and uphill transport of divalent ions. The aim of this study was to investigate the causes of these differences and, if possible, to find underlying causes. The approach mainly followed that in literature articles that specifically focused on the effect of divalent ions on RED. It transpired that seven publications were useful because the methodology was well described and sufficient data was published. I found two widely shared misconceptions. The first concerns the role of the stack voltage in uphill transport of divalent ions; itis often thought that the open circuit voltage (OCV) must be taken into account, but it is plausible that the voltage under working conditions is the critical factor. The second debatable point concerns the methodology used to make a series of solutions to study the effect of divalent ions. Typically, solutions with a constant number of moles of salt are used; however, it is better to make a series with a constant ratio of equivalents of those salts. Moreover, it is plausible that the decreased voltage can be explained by the inherently lower Donnan potential of multi-charged ions and that increased resistance is caused by the fact that divalent ions—with a lower mobility there than the monovalent ions—occupy relatively much of the available space in the gel phase of the membrane. While both resistance and voltage play a decisive role in RED and probably also in other membrane processes like electrodialysis (ED), it is remarkable that there are so few publications that focus on measurements on individual membranes. The implications of these results is that research on the effect of divalent ions in RED, ED and similar processes needs to be more structured in the future. Relatively simple procedures can be developed for the determination of membrane resistance in solutions of mixtures of mono- and divalent salts. The same applies to determining the membrane potential. The challenge is to arrive at a standard method for equipment, methodology, and the composition of the test solutions.

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Quantum Chemical Evidence of a Fundamental Difference Between Hydrations and Ion Exchange Selectivities of Sodium and Potassium Ions on Carboxylic and Sulfonic Acid Cation Exchangers

Cited by 2 publications

References 20 publications

Resistance of Ion Exchange Membranes in Aqueous Mixtures of Monovalent and Divalent Ions and the Effect on Reverse Electrodialysis

Resistance of Ion Exchange Membranes in Aqueous Mixtures of Monovalent and Divalent Ions and the Effect on Reverse Electrodialysis

Concepts and Misconceptions Concerning the Influence of Divalent Ions on the Performance of Reverse Electrodialysis Using Natural Waters

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