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

by 1,2, 1,2,*, 2, 1,2 and 2
1
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Huainan 232001, China
2
College of Material Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
*
Author to whom correspondence should be addressed.
Processes 2019, 7(11), 782; https://doi.org/10.3390/pr7110782
Received: 25 September 2019 / Revised: 18 October 2019 / Accepted: 18 October 2019 / Published: 1 November 2019
(This article belongs to the Section Chemical Processes and Systems)
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. View Full-Text
Keywords: coal-associated kaolinite; carbon impurity; density functional theory; adsorption mechanism coal-associated kaolinite; carbon impurity; density functional theory; adsorption mechanism
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MDPI and ACS Style

Lu, F.; Liu, L.; Min, F.; Chen, J.; Zhang, M. Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite. Processes 2019, 7, 782. https://doi.org/10.3390/pr7110782

AMA Style

Lu F, Liu L, Min F, Chen J, Zhang M. Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite. Processes. 2019; 7(11):782. https://doi.org/10.3390/pr7110782

Chicago/Turabian Style

Lu, Fangqin, Lingyun Liu, Fanfei Min, Jun Chen, and Mingxu Zhang. 2019. "Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite" Processes 7, no. 11: 782. https://doi.org/10.3390/pr7110782

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