Molecular insights into the microscopic interaction between lignite and water:A multiscale molecular modelling study
Coal-water interfacial interactions are one of the key scientific issues in clean coal technology.However,the microscopic mech-anism of lignite-water interaction is still unclear in terms of atomic scale structure and electronic properties.There is a lack of systematic investigation on the interaction energy,stable structural features,and interaction nature of different functional groups in lignite with wa-ter molecules.Herein,the molecular mechanism of lignite-water microscopic interaction based on multi-scale molecular simulations was investigated.The interaction between representative model structures of lignite and a single water molecule was investigated by quan-tum chemical calculations.The localized minima configurations of different adsorption sites on lignite and corresponding stable adsorp-tion configurations are obtained.The interaction forms between lignite and water molecules were intuitively illustrated by independent gra-dient model(IGM),which mainly included van der Waals interactions and hydrogen bonds.The electrostatic interaction was quantitatively described and identified as the dominant factor stabilizing the lignite-water interaction by energy decomposition analysis.Furthermore,the assembly behaviors and evolution characteristics of different numbers of lignite molecules interacting with a large number of water molecules were revealed based on molecular dynamics simulations.The aggregation phenomena of lignite molecules in bulk water were elucidated.The molecular dynamics simulation results also confirm that lignite bind to H20 mainly through electrostatic interaction.
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