The interactions between fine particles of coal and kaolinite in aqueous, insights from experiments and molecular simulations

Chen, Jun; Min, Fanfei; Liu, Ling-yun

doi:10.1016/j.apsusc.2018.10.130

Cited by 52 publications

(20 citation statements)

References 31 publications

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“…The comprehensive analysis of adsorption configurations and charge transfer shows that the adsorption mechanism of the carbon impurities on coal-associated kaolinite surface is the comprehensive result of hydrogen-bond formation between the O-containing functional groups in carbon impurities and kaolinite surfaces, as well as the electrostatic attraction between the aromatic rings on the surface of the carbon impurity and the kaolinite surfaces. This result is similar to the interaction mechanism between coal structural units [29] or amine/ammonium salts [10,11] and kaolinite surface in previous publications, the difference is that the electrostatic attraction and hydrogen bonding contribute differently to the interaction in different systems.…”

Section: Electric Charge Analysissupporting

confidence: 90%

“…Both figures reveal that the O-containing functional groups of the two carbon structural units could form hydrogen bonds with the kaolinite surface; furthermore, the benzene ring in the Ph-OH unit lay approximately parallel to the surface after it achieved optimum adsorption on the kaolinite surface. This indicates that the benzene ring interacts with the kaolinite surface, a conclusion consistent with those of previous studies [29,30]. In contrast, the carbon ring of the C-OH unit adopted an approximately perpendicular orientation relative to the surface at its point of optimum adsorption on the kaolinite surface.…”

Section: Analysis Of Adsorption Configurations and Adsorption Energiessupporting

confidence: 89%

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Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Liu

Min

et al. 2019

Processes

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Kaolinite is a difficult-to-float clay existing in coal slurries which negatively impacts coal flotation. A better understanding of its adsorption behavior would improve coal-slurry processing. Carbon impurities in the kaolinite can affect this behavior. The appearance and elemental surface composition of the carbon impurities precipitated by kaolinite oxidative treatment were microscopically analyzed, and their chemical speciation and relative C and O contents were probed. The mechanisms of adsorption on the main kaolinite cleavage planes ((001) and (001) surfaces) for two carbon-impurity structural models, a phenolic hydroxyl unit (Ph–OH) and carbon hydroxyl unit (C–OH), were considered using density functional theory methods. The carbon impurities consisted mainly of C and O, with C present mostly as C–C, C–H, and C–O species, and O existing mainly in –OH and C–O structures. Both Ph–OH and C–OH units adsorbed stably on the kaolinite (001) and (001) surfaces through hydrogen bonding between the hydroxyl groups and surfaces. A strong electrostatic attraction occurred between the Ph–OH benzene ring and kaolinite surfaces, whereas the carbon ring in C–OH did not interact with either surface. Finally, for both units, adsorption on the kaolinite (001) surface was more stable than on the (001) surface.

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Section: Electric Charge Analysissupporting

confidence: 90%

Section: Analysis Of Adsorption Configurations and Adsorption Energiessupporting

confidence: 89%

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Liu

Min

et al. 2019

Processes

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“…The periodic boundary condition was applied for the above models. Molecular dynamics simulation was carried out using the Forcite module in Materials Studio 2017 R2 . The parameters for dynamics simulation were as follows: the universal force field was selected, the temperature was set at 298 K with Nose thermostat, and 4 ns NVT ensemble dynamic relaxation was set to equilibrate the above models.…”

Section: Calculation Detailsmentioning

confidence: 99%

“…Molecular dynamics simulation was carried out using the Forcite module in Materials Studio 2017 R2. 30 The parameters for dynamics simulation were as follows: the universal force field 31 was selected, the temperature was set at 298 K with Nose thermostat, and 4 ns NVT ensemble dynamic relaxation was set to equilibrate the above models. The methods of electrostatic interaction and van der Waals were both Ewald with the cutoff radius of 18.5 Å.…”

Section: Calculation Detailsmentioning

confidence: 99%

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism

Zheng

Chen

et al. 2019

J. Phys. Chem. A

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Heavy metal pollution in farmland soil reduces crop yield and quality and also potentially causes the crisis to human health. Formerly, the fact that silicon fertilizer could effectively reduce the residual concentration of heavy metal in crops has been identified at the tissue level. In this paper, molecular dynamics simulation was employed to investigate the effects of the degree of silicification of silicic acids [namely, the molar ratio of Si(OH) 4 and SiO 2 ] on the Cd(II) bound in the aspect of radial distribution functions and mean square displacements. The results demonstrated that Si(OH) 4 attracted Cd(II) through the coordination, while SiO 2 attracted Cd(II) by the adsorption. In particular, when the degree of silicification was 0, both the bound Cd(II) amount and strength were the maximum value, indicating that the silicon fertilizer had the best efficiency of Cd(II) bound as Si(OH) 4 . By comparing the adsorption energy and electronic transfer of Cd(II) and Si(OH) 4 adsorption onto the SiO 2 surface through the quantum chemical simulation, we concluded that Cd(II) adsorption onto the SiO 2 surface was chemisorption, while the Si(OH) 4 adsorption onto SiO 2 surface was physisorption. Consequently, the adsorption capacity of Cd(II) on the SiO 2 surface was higher than that of Si(OH) 4 adsorption on the SiO 2 surface. Moreover, the compact hydration layers around Cd(II) prevented the process of Cd(II) adsorption on the SiO 2 surface; even so, the counterion Cl − in the system promoted the adsorption process. The mechanism of silicon fertilizer binding heavy metal Cd(II) was investigated and revealed at the molecular and electronic level. This work has expanded the possibility of theoretical guidance for the design of silicon fertilizer.

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“…Many researchers have utilized the simulation method to get a deep understanding of coal structure and reactivity based on the constructed coal molecular models. In these cases, the pore structure, , adsorption mechanism, , and coal effective separation , were mainly explored. For example, the relationship between coal’s deformation structure and methane adsorption at different temperatures and pressures was studied by Pan, who revealed that different deformations of coal showed different adsorption capacities and adsorption isotherms.…”

Section: Introductionmentioning

confidence: 99%

Molecular Model Construction of the Dense Medium Component Scaffold in Coal for Molecular Aggregate Simulation

Lian

Qin

et al. 2020

ACS Omega

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Coal as an important fossil energy has been comprehensively studied in terms of its structure, reactivity, and application. However, there are few publications reported about the formation mechanism of coal. In order to explore the molecular mechanism of the formation of the dense medium component (DMC) aggregate, which is extracted from coal, the molecular model of the DMC scaffold (DMC-S) was constructed based on a number of X-ray photoelectron spectroscopy, 13 C NMR, and ultimate analysis. Then, DMC-S was further optimized, and the periodic boundary condition was added for molecular mechanics and molecular dynamics simulation. The DMC-S molecule model with a density of 1.05 g/cm 3 and a different number of unit cells was obtained after the aforementioned experiments and simulations. When the unit cell contained 12 DMC-S molecules, the absolute value of electrostatic energy significantly increased and the peripheral branch chains in DMC-S interlaced with each other, forming a compact aggregate. The density and macrosize calculated values are all slightly lower than the true relative values because the presence of minerals or small molecules was not included in the model construction. Despite some unavoidable defects, the comparison between the simulated and experimental results validates the DMC-S aggregate model and lays a solid foundation for an in-depth study of DMC and its reactivity.

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The interactions between fine particles of coal and kaolinite in aqueous, insights from experiments and molecular simulations

Cited by 52 publications

References 31 publications

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism

Molecular Model Construction of the Dense Medium Component Scaffold in Coal for Molecular Aggregate Simulation

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