Thermodynamics of ion exchange coupled with swelling reactions in hydrated clay minerals

Subramanian, Nithya; Lammers, Laura N.

doi:10.1016/j.jcis.2021.09.106

Cited by 14 publications

(5 citation statements)

References 44 publications

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“…This unexpected salt uptake in the adsorbed film as liquid water content decreases is likely associated with two phenomena: first, thinning of the water meniscus enhances salinity in the bulk-liquid phase because of salt exclusion from the water–air interface, ,, and second, a lower dielectric constant in the thin film may promote ion pairing with decreasing film thickness. , Overall, our results show that the ion distribution between the bulk liquid and clay regions depends on the water content and salinity because of competition between salt exclusion from the water–air interface and anion exclusion from the negatively charged clay surface. This observation is consistent with previous studies reporting a sensitivity of cation exchange to water content and salinity for smectite particles. − …”

Section: Resultssupporting

confidence: 93%

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Hygroscopic Growth of Adsorbed Water Films on Smectite Clay Particles

Li,

Bourg

2024

Environ. Sci. Technol.

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Hygroscopic growth of adsorbed water films on clay particles underlies a number of environmental science questions, from the air quality and climate impacts of mineral dust aerosols to the hydrology and mechanics of unsaturated soils and sedimentary rocks. Here, we use molecular dynamics (MD) simulations to establish the relation between adsorbed water film thickness (h) and relative humidity (RH) or disjoining pressure (Π), which has long been uncertain due to factors including sensitivity to particle shape, surface roughness, and aqueous chemistry. We present a new MD simulation approach that enables precise quantification of Π in films up to six water monolayers thick. We find that the hygroscopicity of phyllosilicate mineral surfaces increases in the order mica < K-smectite < Na-smectite. The relationship between Π and h on clay surfaces follows a double exponential decay with e-folding lengths of 2.3 and 7.5 Å. The two decay length scales are attributed to hydration repulsion and osmotic phenomena in the electrical double layer (EDL) at the clay−water interface.

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Section: Resultssupporting

confidence: 93%

“…This observation is consistent with previous studies reporting a sensitivity of cation exchange to water content and salinity for smectite particles. 92 − 94 …”

Section: Resultsmentioning

confidence: 99%

Hygroscopic Growth of Adsorbed Water Films on Smectite Clay Particles

Li,

Bourg

2024

Environ. Sci. Technol.

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“…This is probably because the calcinated ore comprised mainly muscovite, quartz and corundum phases, which cannot react with oxalic acid during the leaching process. Also, it could indicate that, during the leaching process, the dissociated H + from oxalic acid engaged in ion exchange with the Li + present in the layered silicates [24]. The surface morphology of the raw ore, calcinated ore, and the leaching residue was investigated, and the results are shown in Figure 11.…”

Section: Lithium Extraction Mechanismmentioning

confidence: 99%

Lithium Extraction from Lithium-Bearing Clay Minerals by Calcination-Leaching Method

Liu,

Xu,

Sun

et al. 2024

Minerals

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Lithium is a significant energy metal. This study focuses on the extraction of lithium from lithium-bearing clay minerals utilizing calcination combined with oxalic acid leaching. The relevant important parameters, leaching kinetics analysis, and the lithium extraction mechanism were deeply investigated. The results demonstrate that a high lithium recovery of 91.35% could be achieved under the optimal conditions of calcination temperature of 600 °C, calcination time of 60 min, leaching temperature of 80 °C, leaching time of 180 min, oxalic acid concentration of 1.2 M, and liquid-to-solid ratio of 8:1. According to the shrinkage core model, the leaching kinetics of lithium using oxalic acid followed a chemical reaction-controlled process. XRD, TG, and SEM analysis showed that the kaolinite, boehmite, and diaspore phases in raw ore transformed into corundum, quartz, and muscovite phase in calcination products when the calcination temperature was higher than 600 °C. Moreover, the expansion of the interlayer spacing of minerals during the calcination process could promote the lithium release. During the leaching process, lithium present in the layered silicates was efficiently recovered through ion exchange with the dissociated H+ from oxalic acid. This study could provide a promising guide for lithium extraction from lithium-bearing clay minerals.

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“…Similarly, the clay mineral models used in MD to simulate the performance of clay minerals in aqueous environments is either undoped or only partially doped with interlayer ions or impurity atoms. Liao et al [94] used pure kaolinite as the skeleton to study the decomposition behavior of hydrate in the pure water flow system by MD method. Subramanian and Lammers [95] investigated the thermodynamics of ion exchange (Na + and K + ) focusing on a water-layer hydration state via MD simulations.…”

Section: Computational Model Idealizationmentioning

confidence: 99%

Molecular simulation in surface hydration of clay minerals: a review of theory and applications

Min¹,

Wang²,

Liu³

et al. 2022

Miner Miner Mater

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Clay minerals, which are prevalent gangue minerals, are found in tailings and beneficiation effluent after the extraction of valuable minerals. The surface of clay mineral particles is easy to hydrate, which makes it the main factor restricting tailings separation and wastewater treatment. However, the microscopic mechanism of clay mineral particle surface hydration is not yet systematic. In recent years, with the development of molecular simulation theory and the improvement of computational efficiency, density functional theory (DFT) and molecular dynamics (MD) have gradually become a powerful tool for studying the surface hydration of clay mineral particles, which provides new insight into the interaction between the crystal structures of clay minerals and the interfacial interaction in surface hydration of clay mineral particles at the molecular or atomic levels. This article first reviews the basic theory of DFT and MD, then reviews the research progress on clay mineral surface hydration. From the perspective of molecular simulation, a comprehensive discussion of the clay mineral phase structure, the establishment of the supercell surface model, the clay-water interface interaction and the limitations of molecular simulation was conducted. Water molecules can adsorb with different mineral surfaces in slime water through hydrogen bond, which is the basis of surface hydration mechanism. The hydration layer is composed of three water layers with different densities, with a thickness of about 8-10 Å. Water and ions form hydrate cations, which are adsorbed on the surface of clay minerals, change the structure of water layer on the surface of minerals. This article ends with a brief discussion of conclusions and perspectives.

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Thermodynamics of ion exchange coupled with swelling reactions in hydrated clay minerals

Cited by 14 publications

References 44 publications

Hygroscopic Growth of Adsorbed Water Films on Smectite Clay Particles

Hygroscopic Growth of Adsorbed Water Films on Smectite Clay Particles

Lithium Extraction from Lithium-Bearing Clay Minerals by Calcination-Leaching Method

Molecular simulation in surface hydration of clay minerals: a review of theory and applications

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