Molecular Model of Xishan Bituminous Coal Surface and Its Wetting Properties

Abstract

Microscopic understanding of the coal surface structure offers opportunities to enhance coal preparation and utilization. This study contributes to the construction of a surface model of Xishan bituminous coal based on a recently proposed coal bulk model. An XPS survey spectrum reveals that the surface of this coal sample was partially oxidized by atmospheric oxygen. Therefore, different oxygen-containing groups were randomly incorporated into a 3 nm surface layer of the original surface model to represent the realistic oxidized coal surface based on the XPS and NMR results. We also probed the wetting properties of this model both in water and in methanol. The possible reasons for the discrepancy between the computed and experimental values were also discussed. Although both water and methanol can penetrate and fill micropores in the coal surface layer, methanol is found to swell coal to a greater extent than water. The association of coal molecules in this model is caused mainly by van der Waals energy. However, the wetting of the coal surface layer predominantly decreases the electrostatic interactions of coal−coal. In agreement with the wetting experiments, methanol is more effective to reduce the interaction of coal−coal than water.

Study on Surface Activity of Inorganic Salts on [C12MIm]Cl and Wetting Characteristics of Compound Modified Bituminous Coal

“…There were significant differences in peak areas of reactive groups in modified coal samples compared to those in virgin coal. The infrared spectrum of coal has been studied and divided into four regions. , …”

“…The infrared spectrum of coal has been studied and divided into four regions. 37,38 3.2.1. 900−700 cm −1 Aromatic Structure Analysis.…”

Understanding the Role of Polyvinylpyrrolidone on Ultrafine Low-Rank Coal Flotation

“…Therefore, the carbon/ oxygen ratio increment of SBC (increased to 4.88 after PVP treatment) confirmed polar interactions between the lactam group of PVP and the hydrophilic sites (oxygen functional groups) at the surface of SBC. 48,49 The relative amount of Si decreased from 1.6% to 1.3% and the N content reached 5.2% after PVP treatment, which was additional strong evidence of polar interaction. (Figure 9c) correspond to CO groups.…”

Quantifying the Structural Transitions of Chinese Coal to Coal-Derived Natural Graphite by XRD, Raman Spectroscopy, and HRTEM Image Analyses

“…Samples were pulverized to −200 mesh. Demineralization was performed using a threestep HCl−HF acid treatment, 43 in which 5 g of the sample was dispersed in 30 mL of HCl solution (37 wt %), and 20 mL of HF solution (40 wt %); then d the mixture was stirred for 12 h. This process was performed sequentially three times. The samples were filtered and washed with deionized water until the pH value was 7.…”