辉钼矿和黄铁矿的晶体结构与表面性质研究
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摘要
利用密度泛函理论研究了辉钼矿和黄铁矿的晶体结构及表面性质。研究发现,辉钼矿的禁带宽度比黄铁矿大。辉钼矿(001)面的表面能明显小于(100)面,故辉钼矿易倾向于平行(001)面完全解离;辉钼矿(001)面的氧化反应位点为Mo原子,还原反应位点为Mo和S原子,而(100)面的氧化还原反应位点均为Mo原子;黄铁矿倾向于平行(100)面极不完全解离,(100)面的氧化还原反应位点均为Fe原子。原子电荷及化合键Mulliken布居显示,辉钼矿(100)面上原子所带的电荷数明显高于(001)面,所以(100)面与浮选药剂的静电作用将明显强于(001)面;辉钼矿(001)面的S—Mo键共价性大于(100)面,表明(001)面的疏水性大于(100)面。由此可知,辉钼矿(001)面倾向于与非极性药剂作用,而(100)面则更易于与极性药剂发生作用。
The crystal structures and surface properties of molybdenite and pyrite were investigated by first-principle calculation. A band structure analysis suggested that the forbidden band width of molybdenite was larger than that of pyrite. The surface energy of MoS_2(001) plane was significantly lower than that of MoS_2(100) plane, which indicated that the molybdenite tended to completely disintegrate parallel(001) plane. On MoS_2(001) plane, the oxidation reaction sites were Mo atoms and reduction ones were Mo and S atoms. While both the oxidation and the reduction reaction sites on MoS_2(100) plane were Mo atoms. Pyrite tended to incompletely disintegrate parallel(100) plane, and the oxidation-reduction reaction sites thereon were Fe atoms. Moreover, the results of Mulliken distribution analysis of atom charge and chemical bonds showed that the atom charge of MoS_2(100) plane was obviously higher than that of MoS_2(001) plane, so it would have a stronger electrostatic attraction with flotation reagents. However, the S-Mo bond covalency of (001) plane was larger than that of(100) plane, indicating the hydrophobicity of MoS_2(001) plane was stronger than that of MoS_2(100) plane. It can be inferred that the molybdenite(001) plane tends to interact with nonpolar reagents and(100) plane is prone to interact with polar reagents.
The crystal structures and surface properties of molybdenite and pyrite were investigated by first-principle calculation. A band structure analysis suggested that the forbidden band width of molybdenite was larger than that of pyrite. The surface energy of MoS_2(001) plane was significantly lower than that of MoS_2(100) plane, which indicated that the molybdenite tended to completely disintegrate parallel(001) plane. On MoS_2(001) plane, the oxidation reaction sites were Mo atoms and reduction ones were Mo and S atoms. While both the oxidation and the reduction reaction sites on MoS_2(100) plane were Mo atoms. Pyrite tended to incompletely disintegrate parallel(100) plane, and the oxidation-reduction reaction sites thereon were Fe atoms. Moreover, the results of Mulliken distribution analysis of atom charge and chemical bonds showed that the atom charge of MoS_2(100) plane was obviously higher than that of MoS_2(001) plane, so it would have a stronger electrostatic attraction with flotation reagents. However, the S-Mo bond covalency of (001) plane was larger than that of(100) plane, indicating the hydrophobicity of MoS_2(001) plane was stronger than that of MoS_2(100) plane. It can be inferred that the molybdenite(001) plane tends to interact with nonpolar reagents and(100) plane is prone to interact with polar reagents.
引文
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[2] Castro S,Lopez-Valdivieso A,Laskowski J S.Review of the flotation of molybdenite.Part I:Surface properties and floatability[J].International Journal of Mineral Processing,2016,148:48-58.
[3] Lu Zhenzhen,Liu Qingxia,Xu Zhenghe,et al.Probing anisotropic surface properties of molybdenite by direct force measurements[J].Langmuir,2015,31(42):11409-11418.
[4] Kitchaev D A,Ceder G.Evaluating structure selection in the hydrothermal growth of FeS2 pyrite and marcasite[J].Nature Communications,2016(7):13799-13805.
[5] Schonfeld B,Huang J J,Moss S C.Anisotropic mean-square displacements (MSD) in single crystals of 2H- and 3R-MoS2[J].Acta Crystallographica,1983,B39:404-407.
[6] Rieder M,Crelling J C,Sustai O,et al.Arsenic in iron disulfides in a brown coal from the North Bohemian Basin,Czech Republic[J].International Journal of Coal Geology,2007,71(2):115-121.
[7] Edelbro R,Sandstrom A,Paul J.Full potential calculations on the electron bandstructures of Sphalerite,Pyrite and Chalcopyrite[J].Applied Surface Science,2003,206(1-4):300-313.
[8] Dickinson R G,Pauling L.The crystal structure of molybdenite[J].Journal of the American Chemical Society,1923,45(6):1466-1471.
[9] Zhu Guangli,Wang Yuhua,Liu Xiaowen,et al.The cleavage and surface properties of wet and dry ground spodumene and their flotation behavior[J].Applied Surface Science,2015,357:333-339.
[10] Ke Baolin,Li Yuqiong,Chen Jianhua,et al.DFT study on the galvanic interaction between pyrite (100) and galena (100) surfaces[J].Applied Surface Science,2016,367:270-276.
[11] 冯其明,陈建华.硫化矿物浮选电化学[M].长沙:中南大学出版社,2014.