基于量子化学的碳原子吸附对煤系黄铁矿表面疏水性影响的研究

发布时间：2018-07-17 02:39

【摘要】：与黄铁矿硫共生的碳质提高了煤系黄铁矿在煤泥浮选过程中的可浮性,为了降低煤系黄铁矿的可浮性及脱除精煤中的黄铁矿,分析煤系黄铁矿碳质中碳元素的存在形式及其与疏水性关系的机理具有重要的意义。采用微量热仪和扫描电子显微镜比较了中国典型矿区的矿系黄铁矿和煤系黄铁矿的润湿热及表面碳质中碳元素含量差异,试验结果表明:与矿系黄铁矿相比,各煤系黄铁矿的润湿热绝对值均较小,碳质中碳元素含量较高,导致疏水性可能因表面吸附碳原子而较强。采用基于密度泛函理论(DFT)和平面波赝势的方法模拟了水分子在理想黄铁矿表面及含碳原子吸附的黄铁矿表面的吸附过程并计算了水分子的吸附能、键Mulliken布居及键长、电荷密度及电子态密度。计算结果表明:与理想黄铁矿表面相比,水分子在含碳原子吸附的煤系黄铁矿表面的吸附能由负值变为正值,吸附碳原子处的黄铁矿表面变成疏水性,黄铁矿表面铁原子的3d轨道先与碳原子的2p轨道形成强烈的Fe—C键,碳原子的2p轨道再与水分子中氧原子的2p轨道形成微弱C—O键,因C—O键作用微弱导致碳原子的吸附不利于水分子在黄铁矿表面的吸附,从量子化学的角度揭示了煤系黄铁矿表面吸附碳原子后对其疏水性影响的机理。
[Abstract]:In order to reduce the floatability of coal series pyrite and remove pyrite from concentrate coal, the carbonaceous coexisting with pyrite can improve the floatability of coal series pyrite in the process of coal slime floatation, in order to reduce the floatability of coal series pyrite and to remove pyrite from concentrate coal. It is of great significance to analyze the forms of carbon elements in coal pyrite and its relationship with hydrophobicity. The wetting heat and surface carbon content of pyrite and coal pyrite in typical mining areas in China are compared by means of microcalorimeter and scanning electron microscope. The experimental results show that: compared with pyrite of ore series, The moisture and heat absolute values of each coal series pyrite are small, and the content of carbon elements in carbon is higher, which may lead to the hydrophobicity of pyrite being stronger because of the adsorption of carbon atoms on the surface. Based on density functional theory (DFT) and plane wave pseudopotential method, the adsorption process of water molecules on ideal pyrite surface and pyrite surface containing carbon atom was simulated, and the adsorption energy, bond Mulliken population and bond length of water molecule were calculated. Charge density and electron density of state. The results show that compared with the ideal pyrite surface, the adsorption energy of water molecules on coal series pyrite adsorbed by carbon atom changes from negative value to positive value, and the surface of pyrite adsorbed at carbon atom becomes hydrophobic. On the surface of pyrite, the 3D orbital of iron atom forms a strong Fe-C bond with the 2p orbital of carbon atom, and the 2p orbital of carbon atom forms a weak C-O bond with the 2p orbital of oxygen atom in water. The adsorption of carbon atoms by C-O bonds is not conducive to the adsorption of water molecules on the surface of pyrite. From the perspective of quantum chemistry, the mechanism of the effect of adsorption of carbon atoms on the hydrophobicity of coal series pyrite is revealed from the perspective of quantum chemistry.
【作者单位】：中国矿业大学(北京)化学与环境工程学院;安徽理工大学材料科学与工程学院;
【基金】：中央高校基本科研业务费资助项目(2010YH11)
【分类号】：O647.3;TD923

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