Molecular dynamics simulation study on influence of different oxygen-containing functional groups on coal wettability
In order to explore the influence of different oxygen-containing functional groups on coal wettability,based on the molecular dynamics(MD)theory,the simulation systems of four different oxygen-containing functional groups(—COOH,—OH,—CO and—OCH3)were constructed,and the influence of these oxygen-containing functional groups on coal wettabil-ity was analyzed in detail by simulating the contact angle,molecular relative volume fraction,radial distribution function and interaction energy.The results show that after simulating equilibrium,the contact angle of water clusters in the—COOH sys-tem is 18.65°,the interaction energy is-1 049.19 kcal/mol,and 371.64 hydrogen bonds are formed.In the—OH system,the contact angle of water clusters is25.37°,the interaction energy is-563.83 kcal/mol,and 178.03 hydrogen bonds are formed.In the—CO system,the contact angle of water clusters is 30.10°,the interaction energy is-444.25 kcal/mol,and 58.34 hydrogen bonds are formed.In the—OCH3 system,the contact angle of water clusters is 59.96°,the interaction energy is-149.00 kcal/mol,and 13.25 hydrogen bonds are formed.The smaller the contact angle between water clusters and dif-ferent oxygen-containing functional groups,the more hydrogen bonds are formed,the greater the absolute value of interaction energy,and the better the enhancing effect of coal hydrophilicity,which is consistent with the analysis results of molecular rel-ative volume fraction and radial distribution function.The order of enhancing coal hydrophilicity by different oxygen-contai-ning functional groups is—COOH>—OH>—CO>—OCH3.The research results can provide relevant reference for the study of coal surface wettability and its application.
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