DFT study of water adsorption on lignite molecule surface

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• 作者：Zhengyang Gao ; Yi Ding ; Weijie Yang ; Wentao Han
• 关键词：Electrostatic potential ; Energy decomposition analysis ; Lignite ; Reduced density gradient ; Water adsorption
• 刊名：Journal of Molecular Modeling
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：23
• 期：1
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Computer Applications in Chemistry; Molecular Medicine; Computer Appl. in Life Sciences; Characterization and Evaluation of Materials; Theoretical and Computational Chemistry;
• 出版者：Springer Berlin Heidelberg
• ISSN：0948-5023
• 卷排序：23

文摘

High moisture content is a main characteristic of low-rank coal, such as lignite. Numerous oxygen containing functional groups in lignite make it represent some special properties, and these functional groups affect the adsorption mechanisms of water molecules on lignite surface. This study reports some typical water · · · lignite conformations, along with a detailed analysis of the geometry, electrostatic potential distribution, reduced density gradient of interaction, and interaction energy decomposition. The results show that water molecules tend to aggregate around functional groups, and hydrogen bonds play a dominant role in the interaction. The adsorption energy of water cluster on lignite surface is larger than that of isolated water molecule, a good linear relationship between the interaction distance and adsorption energy of layers has been found. Since water is a polar molecule, the local minima and maxima of electrostatic potential in conformations increase along with more water adsorbing on lignite surface. Reduced density gradient analysis shows that H-bonds, van der Waals interaction, and a little steric make up the interaction between water cluster and lignite molecule. In these studied conformations which mainly are H-bond complexes, electrostatic and exchange repulsion play a dominant role, whereas polarization and dispersion make relatively small contribution to the interaction. Attractive and repulsive interaction both affect the stability of water · · · lignite conformations.