New insight into surface wetting of coal with varying coalification degree: An experimental and molecular dynamics simulation study

Zhang, Rui; Xing, Yaowen; Xia, Yangchao; Luo, Jun; Tan, Jinlong; Rong, Guoqiang; Gui, Xiahui

doi:10.1016/j.apsusc.2020.145610

Cited by 105 publications

(36 citation statements)

References 37 publications

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“…This result is consistent with the previous findings and the law of surface wettability of coal. 22 The BC surface has a large contact angle and strong hydrophobicity, 28 , 29 allowing the nitrogen gas bubbles to easily attach to the hydrophobic surface, whereas the attachment rate of the nitrogen gas bubbles is the slowest for the LRC surface owing to the smallest contact area and the poorest hydrophobicity.…”

Section: Resultsmentioning

confidence: 99%

“…Li 21 et al calculated for the first time the wetting process of water droplets on a smooth mineral surface. Similarly, Zhang 22 et al used MDS to calculate the water contact angle of a coal surface with different degrees of coalification and compared the experimental results. They found that the simulated contact angle was consistent with the experimental test results.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the previous study about water droplet spreading on the coal surface with different degrees of coalification in air, 22 the dynamics of bubble attachment on different hydrophobic coal surfaces in water were further examined in this work, and the results were compared with the experimental contact angles. During the simulation process, the bubble attachment efficiency of different hydrophobic coal surfaces was considered, and it was verified that the bubble attachment rate was fast on a large hydrophobic coal surface, and it is slow on a weak hydrophobic coal surface.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulation Study of Bubble Attachment at the Coal Surface with Varying Coalification Degrees

et al. 2020

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Establishing the dynamics of wetting film thinning and rupture during the bubbles attached on the coal surface is extremely important for flotation. However, studying the dynamics of bubble attachment from the molecular level using molecular dynamics simulation (MDS) has rarely been reported. In this work, the dynamics of bubble attachment at three different coal [low-rank coal (LRC), bituminous coal (BC), and anthracite coal (AC)] surfaces with varying degrees of coalification were studied using MDS. In the bubble attachment process, the wetting film between the bubble and coal surface gradually become thinner until it ruptures. By comparing the bubble attachment dynamics on three different coal surfaces, the results indicate that the bubble attachment rate on the surface with strong hydrophobicity is faster than that on the surface with weak hydrophobicity. Besides, the number of hydrogen bonds between the molecules of the wetting film is decreased with the attachment of bubbles; however, it is sharply decreased on the BC surface and slowly reduces on the LRC surface before the film rupture. At the same time, the radial distribution functions (RDFs) of hydrogen bonds in the wetting film at the moment of bubble attachment on the coal surface are analyzed, indicating that the peak intensity of the RDF decreases at the time of bubble attachment. The findings in this study may help to better comprehend the dynamics of bubble attachment, which is valuable for future design in practical applications.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulation Study of Bubble Attachment at the Coal Surface with Varying Coalification Degrees

et al. 2020

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“…[1][2][3][4]. However, since a large number of hydrophilic oxygen-containing functional groups and pores exist on the low-rank coal, a stable hydration layer can be formed on the surface during the flotation process [5][6][7][8][9]. Therefore, the traditional oil flotation collector is difficult to adsorb on its surface, which ultimately leads to low flotation efficiency of low-rank coal [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, with the rapid development of computer simulation technology, molecular simulation has become an effective means for investigating adsorption processes and the interfacial interaction in flotation [5,[23][24][25][26]. Xia et al carried out molecular dynamics simulations (MD) to study the adsorption process of dodecane on low-rank coal in the presence of DTAB.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydration Layer on the Adsorption of Dodecane Collector on Low-Rank Coal: A Molecular Dynamics Simulation Study

et al. 2020

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The hydration layer has a significant effect on the adsorption behavior of reagents during the flotation process of low-rank coal. Understanding the effect of hydration layer on the adsorption of common collectors on low-rank coal is a prerequisite for proposing a new enhanced coal floatation method. In this study, a smooth low-rank coal surface model with a density of 1.2 g/cm3 was constructed and compared with the XPS results. Three different systems, coal-water, coal-collector, and coal-water-collector, were constructed. Molecular dynamics method was applied to study the adsorption behaviors of water and dodecane molecules. Simulation results revealed that a stable hydration layer with a thickness of about 5 Å was formed due to the strong attraction of coal surface. The negative value of interaction energy (IE) indicated that dodecane molecules could spontaneously adsorb on the coal surface. Dodecane molecules were successfully adsorbed on the coal surface when it was located inside the hydration layer. While the dodecane molecule was outside the hydration layer, it could not pass through the hydration layer on the surface of low-rank coal.

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Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Zhao,

Liu

2023

Int J of Quantum Chemistry

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Flotation of fine coal particles usually uses oil collectors, but the micromechanisms need to be more refined due to the complex structure and abundant functional groups on the surface of coal bodies. The adsorption spreading behavior and interfacial properties of nonpolar oil drops on flat low‐order coal (LOC) and high‐order coal (HOC) surfaces were investigated in depth using molecular dynamics (MD) simulations, while the effects of different functional groups on LOC surfaces were also considered. The results showed that the contact angle, contact area and interaction energy of oil drops adsorbed on the LOC and HOC surfaces at simulated equilibrium in aqueous environment were 77.68°, 621.49 Å2, −140.94 kcal/mol; 53.98°, 962.14 Å2, and −195.13 kcal/mol, respectively. The smaller the equilibrium contact angle between the oil drops and the surface, the larger the contact area and the larger the absolute value of the interaction energy, the better the spreading effect of the oil drops and the easier the surface is to flotation. Compared with the HOC surface, the oil drops could not displace the water molecules on the LOC surface better and spread poorly on its surface, and the migration rate was higher. This was caused by the abundant functional groups on the surface of LOC. The type of functional group significantly affects the interaction of nonpolar oil drops with hydrophilic surfaces, with the order of adsorption strength being CH3 > COCH3 > OH > COOH. The formation of a dense hydrated film of oil drops on the COOH surface was an important reason for the difficulty of flotation on the LOC surface. MD elucidated the mechanism of action of nonpolar oil collectors on LOC and HOC surfaces, which is a guide for efficient flotation on LOC surfaces.

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New insight into surface wetting of coal with varying coalification degree: An experimental and molecular dynamics simulation study

Cited by 105 publications

References 37 publications

Molecular Dynamics Simulation Study of Bubble Attachment at the Coal Surface with Varying Coalification Degrees

Molecular Dynamics Simulation Study of Bubble Attachment at the Coal Surface with Varying Coalification Degrees

Effect of Hydration Layer on the Adsorption of Dodecane Collector on Low-Rank Coal: A Molecular Dynamics Simulation Study

Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

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