Molecular Dynamics Study of Crystalline Swelling of Montmorillonite as Affected by Interlayer Cation Hydration

Li, Hongliang; Song, Shaoxian; Dong, Xianshu; Min, Fanfei; Zhao, Yunliang; Peng, Chenliang; Nahmad, Yuri

doi:10.1007/s11837-017-2666-2

Cited by 32 publications

(9 citation statements)

References 28 publications

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“…The hydration structure of interlayer water surrounding various cations and the coordination environments have been represented by molecular simulation studies. − These studies have indicated that interfacial interactions among clay surfaces, interlayer exchangeable cations, and interlayer water generate different hydration structures and diffusions of water and cations in the clay framework, resulting in different swelling abilities. For example, the larger hydration energies of kosmotropes such as Ca 2+ ions relative to borderline ions such as Na + induce more pronounced association of water molecules with Ca 2+ ions.…”

Section: Resultsmentioning

confidence: 99%

Effect of Cations on Interlayer Water Dynamics in Cation-Exchanged Montmorillonites Studied by Nuclear Magnetic Resonance and X-ray Diffraction Techniques

Rongwei

Tsukahara

2020

ACS Earth Space Chem.

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To ensure the safety of geological disposal of radioactive wastes, understanding the migration behavior of radioactive species in montmorillonite clays has become increasingly important. However, there are still many indeterminate aspects about the influence of cation species and humidity on the interlayer water dynamics and swelling properties of montmorillonite clays. In this work, by using X-ray diffraction (XRD) and proton nuclear magnetic resonance spin–lattice relaxation rate (1/T 1) techniques, we aimed to clarify the relation between water layer thickness and molecular dynamics in various cation-exchanged montmorillonites (M n+-MMTs; M n+ = Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, La3+, Sm3+, and Lu3+) in the temperature range of −40 to 50 °C. XRD measurements showed that layer thickness in M n+-MMTs increased with increasing hydrated water according to the order of structure-breaking chaotropic K+, Rb+, and Cs+ ions, structure-making kosmotropic and borderline Li+, Na+, and Ba2+ ions, divalent ions, and trivalent lanthanide ions. It was found that the 1/T 1 values are linearly correlated with d 001 basal spacing and increase in the interlayer thickness induces acceleration of the motion of the interlayer water molecules. The temperature dependence of the 1/T 1 values verified that interparticle water and interlayer water, regardless of whether it was frozen or unfrozen, coexist above approximately −5 °C, but only unfrozen interlayer water with poor hydrogen bonding rearrangement properties exists below −5 °C. Moreover, the T 1-distribution results suggest that motions of the water molecules in the M n+-MMTs can be uniquely characterized by a value of about 0.2 ms under supercooled environments because of dominant water–surface interactions.

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Section: Resultsmentioning

confidence: 99%

Effect of Cations on Interlayer Water Dynamics in Cation-Exchanged Montmorillonites Studied by Nuclear Magnetic Resonance and X-ray Diffraction Techniques

Rongwei

Tsukahara

2020

ACS Earth Space Chem.

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“…Its general formula can be written as (Na,Ca) 0.33 (Al,Mg) 2 (Si 4 O 10 )(OH) 2 •nH 2 O. In contact with water, it can reversibly swell up to 15 times of its original volume, forming gelatinous colloidal suspensions or plastic films [6]. Subordinate minerals can be cristobalite, tridymite, feldspar, halloysite, kaolinite [7,8].…”

Section: Introductionmentioning

confidence: 99%

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Damian

Szakács

et al. 2021

Minerals

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The objective of this study is to describe the mineralogical composition and chemical properties of the Oraşu Nou bentonite, from northwestern Romania. For mineralogical determinations, the following were used: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FR-IR), thermogravimetric analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The chemical compositions and physical properties of the bentonites and bentonitized rocks were also determined. Calcium type montmorillonite is the predominant mineral in this deposit. Its average mass fraction is between 35% and 75%, reaching up to 95%. A small amount of halloysite and very fine cristobalite were also identified in the fine fraction. Quartz, feldspar, and kaolinite were identified as impurities. The average pH of natural bentonite is 6.2. Its cation exchange capacity (CEC) is in the lower-middle range for smectites at 45.89 cmol/kg, absorption capacity 43.58 mL/g, swelling degree 9.41%. Because of the high amounts and purity of montmorillonite, the valuable component mineral, the way is open to an easy refinement of this important resource. This way very high-quality colloidal suspensions can be obtained which can be used in the most modern applications of micro- and nanostructured materials.

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“…Kaolinite is a nonswelling clay and montmorillonite is a swelling clay [15]. The swelling properties and water-clay interaction have received extensive attention and are considered to be the most influential factors affecting the dewatering of clay-related materials [16][17][18][19][20]. Foster [21] investigated the relationship of composition and swelling in clays.…”

Section: Introductionmentioning

confidence: 99%

Impact of Clay Minerals on the Dewatering of Coal Slurry: An Experimental and Molecular-Simulation Study

Fan

Dong

et al. 2018

Minerals

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The cleaning process of coals is challenging due to the existence of clay minerals. The overall objective of this study is to investigate how the dewatering of coal slurry is impacted by the presence of clay minerals, i.e., kaolinite and montmorillonite. Filtration tests were first conducted to investigate the effect of kaolinite and montmorillonite on the dewatering efficiency of coal. Specifically, we measured the filtration velocity, moisture, average specific resistance, and porosity of filter cakes for six slurry samples, in which different amounts of kaolinite and montmorillonite were contained. Filtration tests show that a small amount of kaolinite and montmorillonite leads to a significant reduction in the filtration velocity and porosity, and a big increase in the average specific resistance and the moisture of the filter cake. We observe that most kaolinite existed in the top and middle layers of the filter cake, while most montmorillonite existed in the top layer; on the contrary, little montmorillonite is observed in the middle and bottom layers of the filter cake. Montmorillonite results in a much more deteriorative effect than kaolinite. Considering that the interactions between clay minerals and water may play a key role, we then further investigate the effect of such interactions using molecular simulations. Simulation results show that water molecules could hardly diffuse into kaolinite from the edge, while they could readily penetrate into the montmorillonite layers from the edge surface. This result can be explained by the hydrated cation in montmorillonite. The adsorption density of water on the octahedral surface of kaolinite is higher than that of water on the tetrahedral surface of kaolinite. Furthermore, the adsorption density of water on the double surfaces of kaolinite is higher than that of water on the montmorillonite surface. This research is expected to provide benefits or contributions to the dewatering of clay-rich coal tailings.

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Molecular Dynamics Study of Crystalline Swelling of Montmorillonite as Affected by Interlayer Cation Hydration

Cited by 32 publications

References 28 publications

Effect of Cations on Interlayer Water Dynamics in Cation-Exchanged Montmorillonites Studied by Nuclear Magnetic Resonance and X-ray Diffraction Techniques

Effect of Cations on Interlayer Water Dynamics in Cation-Exchanged Montmorillonites Studied by Nuclear Magnetic Resonance and X-ray Diffraction Techniques

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Impact of Clay Minerals on the Dewatering of Coal Slurry: An Experimental and Molecular-Simulation Study

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