Abstract
From the macroscopic point of view, the hydrophilicity of symbiotic carbon pyrite is weakened overall compared to that of pure pyrite. It is very important to explain the impact of elemental carbon accreted on a pyrite surface on the surface’s hydrophobicity from the perspective of quantum chemistry. To study the influence of adsorbed carbon atoms on the hydrophilicity of a coal pyrite surface versus a pyrite surface, the adsorption of a single water molecule at an adjacent Fe site of a one-carbon-atom-covered pyrite surface and a carbon atom monolayer were simulated and calculated with the first-principles method of density functional theory (DFT). The water molecules can be stably adsorbed at the adjacent Fe site of the carbon-atom-covered pyrite surface. The hybridization of the O 2p (H2O) and Fe 3d (pyrite surface) orbitals was the main interaction between the water molecule and the pyrite surface, forming a strong Fe–O covalent bond. The water molecule only slightly adsorbs above a C atom on the carbon-atom-covered pyrite and the carbon atom monolayer surfaces. The valence bond between the water molecule and the pyrite surface changed from an Fe–O bond to an Fe–C–O bond, in which the C–O bond is very weak, resulting in a weaker interaction between water and the surface.
Highlights
The flotation desulfurization theory of coal slime is based on the difference in hydrophobicity between coal and a pyrite surface
To how the carbon atom affects the adsorption of H2O on the adjacent Fe site of the pyrite surface, the water was put atfrom the the
These results indicate that the covalent overlap between C and O was weak to some extent and, that the symbiotic carbon prevented the adsorption of a water molecule on the surface of pyrite to a certain extent
Summary
The flotation desulfurization theory of coal slime is based on the difference in hydrophobicity between coal and a pyrite surface. The properties of a coal pyrite surface are similar to those of coal because of defects in the crystal lattice due to carbon impurities or because of the adsorption of large amounts of carbon on the coal pyrite surface. This leads to the strong floatability of coal pyrite in the flotation process [1]. Shao [2] compared the difference of carbon adsorbed on pyrite and coal pyrite In that work, they proposed that the floatability of coal pyrite was affected by the symbiotic carbon in the coal pyrite or by other forms of carbon, but they did not analyze the mechanism of the influence.
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