DFT Study of The Interaction Characteristics Between the Organic Matter and Minerals In Coal-Series Kaolin

Abstract Coal-series kaolin is an associated mineral resource in coal mining process, often contains organic components and other discoloring impurities, which may lower the quality and limit the industrial application. However, the occurrence, stability of organic component and how they affect the surface physical and chemical properties of coal-series kaolin is known little. In this article, several representative organic components have been enrolled for analyzing the interactions with different minerals of the coal-series kaolin. Results shows that the unsaturated double bonds may be easier to adsorb with kaolinite, and the energy on C20H40 is the least among all the compositions. Among the different crystal planes of kaolinite, the (001) surface may possess higher adsorption characteristic on the organic molecules, which may be consistent with the crystal face index of the kaolinite. While the adsorption energy between the organic molecules and the impurities in coal-series kaolin was positive all the time, suggesting that the organic matter could only adsorb with kaolinite compared with the impurities such as pyrite, quartz and anatase. Calculations of state density also showed that the displacement of the energy band for kaolinite may shift to the lower state after adsorbed with different organic matter, also a rearrangement and significant increase of peak values for the state density may occur after adsorption. This study aims to provide a theoretical basis for the occurrence state and stability differences of different organic matters on the coal-series kaolin, also further solve the long-term problems of restricting the whiteness and comprehensive utilization of coal-series kaolin resources.