Cation Selectivity in Capacitive Deionization: Elucidating the Role of Pore Size, Electrode Potential, and Ion Dehydration

Cerón, Maira R.; Aydin, Fikret; Hawks, Steven A.; Oyarzun, Diego I.; Loeb, Colin K.; Deinhart, Amanda; Zhan, Cheng; Pham, Tuan Anh; Stadermann, Michael; Campbell, Patrick G.

doi:10.1021/acsami.0c07903

Cited by 48 publications

(23 citation statements)

References 67 publications

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“…For example, small changes in the synthesis of hierarchical carbon aerogel monolith led to different ion selectivity; the monoliths were activated for 1 and 3 h, where activation refers to the preferential removal of the most reactive carbon atoms through a reaction with CO 2 at 950°C. For low activated cells (smaller mass loss during activation, and pore size distribution skewed toward smaller pores), Na + was removed, whereas no Ca 2+ was adsorbed (selectivity coefficient >>1), whereas for the highly activated cells (higher mass loss during activation, and pore size distribution skewed toward bigger pores) Ca 2+ was preferred over Na + (selectivity coefficient of 6.6 at 0.6 V, unexpectedly decreasing to 2.2 at 1.2 V) ( Ceron et al., 2020 ).…”

Section: Electrochemical Separations For Selective Recoverymentioning

confidence: 99%

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

Kim¹,

Candeago²,

Rim³

et al. 2021

iScience

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Summary Critical minerals are essential for the ever-increasing urban and industrial activities in modern society. The shift to cost-efficient and ecofriendly urban mining can be an avenue to replace the traditional linear flow of virgin-mined materials. Electrochemical separation technologies provide a sustainable approach to metal recovery, through possible integration with renewable energy, the minimization of external chemical input, as well as reducing secondary pollution. In this review, recent advances in electrochemically mediated technologies for metal recovery are discussed, with a focus on rare earth elements and other key critical materials for the modern circular economy. Given the extreme heterogeneity of hydrometallurgically-derived media of complex feedstocks, we focus on the nature of molecular selectivity in various electrochemically assisted recovery techniques. Finally, we provide a perspective on the challenges and opportunities for process intensification in critical materials recycling, especially through combining electrochemical and hydrometallurgical separation steps.

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Section: Electrochemical Separations For Selective Recoverymentioning

confidence: 99%

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

Kim¹,

Candeago²,

Rim³

et al. 2021

iScience

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“…For more than a decade, extensive molecular dynamics (MD) simulations have been carried out to understand the behavior of confined aqueous solutions and solid/water interfaces. ,− For instance, Köhler et al reviewed the role of interactions between the nanotube walls and water molecules and the degree of confinement on the dynamical and structural properties of fluids . The study discusses the changes in the behavior of confined water because of the competition between the hydrophobic and hydrophilic interactions and suggests that the polarity of the nanotube wall plays a critical role in the formation of high flow rates.…”

Section: Introductionmentioning

confidence: 99%

Ion Solvation and Transport in Narrow Carbon Nanotubes: Effects of Polarizability, Cation−π Interaction, and Confinement

Aydin

Moradzadeh

Bilodeau

et al. 2021

J. Chem. Theory Comput.

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Understanding ion solvation and transport under confinement is critical for a wide range of emerging technologies, including water desalination and energy storage. While molecular dynamics (MD) simulations have been widely used to study the behavior of confined ions, considerable deviations between simulation results depending on the specific treatment of intermolecular interactions remain. In the following, we present a systematic investigation of the structure and dynamics of two representative solutions, that is, KCl and LiCl, confined in narrow carbon nanotubes (CNTs) with a diameter of 1.1 and 1.5 nm, using a combination of first-principles and classical MD simulations. Our simulations show that the inclusion of both polarization and cation−π interactions is essential for the description of ion solvation under confinement, particularly for large ions with weak hydration energies. Beyond the variation in ion solvation, we find that cation−π interactions can significantly influence the transport properties of ions in CNTs, particularly for KCl, where our simulations point to a strong correlation between ion dehydration and diffusion. Our study highlights the complex interplay between nanoconfinement and specific intermolecular interactions that strongly control the solvation and transport properties of ions.

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“…Cerón et al (2020) studied the selectivity of Na + over Ca2 + by a small change in synthesis procedure to adjust pore size distribution of hierarchical carbon aerogel monoliths (HCAM). The procedure involved activation at 950° C while the change in time period of activation, one for 1 h (low‐activated) and another for 3 h (high‐activated).…”

Section: Factors Affecting Electrosorption Performancementioning

confidence: 99%

Recent progress in materials and architectures for capacitive deionization: A comprehensive review

Datar

Mane

Jha

2022

Water Environment Research

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Capacitive deionization is an emerging and rapidly developing electrochemical technique for water desalination across the globe with exponential growth in publications. There are various architectures and materials being explored to obtain utmost electrosorption performance. The symmetric architectures consist of the same material on both electrodes, while asymmetric architectures have electrodes loaded with different materials. Asymmetric architectures possess higher electrosorption performance as compared with that of symmetric architectures owing to the inclusion of either faradaic materials, redox‐active electrolytes, or ion specific pre‐intercalation material. With the materials perspective, faradaic materials have higher electrosorption performance than carbon‐based materials owing to the occurrence of faradaic reactions for electrosorption. Moreover, the architecture and material may be tailored in order to obtain desired selectivity of the target component and heavy metal present in feed water. In this review, we describe recent developments in architectures and materials for capacitive deionization and summarize the characteristics and salt removal performances. Further, we discuss recently reported architectures and materials for the removal of heavy metals and radioactive materials. The factors that affect the electrosorption performance including the synthesis procedure for electrode materials, incorporation of additives, operational modes, and organic foulants are further illustrated. This review concludes with several perspectives to provide directions for further development in the subject of capacitive deionization. Practitioner Points Capacitive deionization (CDI) is a rapidly developing electrochemical water desalination technique with exponential growth in publications. Faradaic materials have higher salt removal capacity (SAC) because of reversible redox reactions or ion‐intercalation processes. Combination of CDI with other techniques exhibits improved selectivity and removal of heavy metals. Operational parameters and materials properties affect SAC. In future, comprehensive experimentation is needed to have better understanding of the performance of CDI architectures and materials.

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Cation Selectivity in Capacitive Deionization: Elucidating the Role of Pore Size, Electrode Potential, and Ion Dehydration

Cited by 48 publications

References 67 publications

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

Ion Solvation and Transport in Narrow Carbon Nanotubes: Effects of Polarizability, Cation−π Interaction, and Confinement

Recent progress in materials and architectures for capacitive deionization: A comprehensive review

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