First Principles Study on Electronic Structure and Lead Activation Mechanism on Cassiterite Surface
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摘要:
用密度泛函理论对锡石表面晶体结构及铅离子活化对苯甲羟肟酸和水杨羟肟酸在锡石表面的吸附过程的影响进行了研究。利用态密度及前线轨道理论分析了铅吸附后锡石(100)表面电子结构的变化。结果表明:铅离子吸附在锡石(100)后会降低表面氧原子的反应活性,增加表面的反应位点。根据前线轨道理论,从能量角度比较了苯甲羟肟酸和水杨羟肟酸与锡石(100)表面的相互作用能,揭示了羟肟酸浮选锡石的本质。
Abstract:The influence of the crystal structure of cassiterite surface and the activation of lead ion on the adsorption process of benzohydroxamic acid and salicylic oxime on cassiterite surface was studied by density functional theory. The electronic structure of cassiterite (100) after lead adsorption is analyzed by using the density of States and frontier orbital theory. The results show that the adsorption of lead ions on cassiterite (100) will reduce the reactivity of the surface oxygen atoms and increase the reaction sites on the surface. According to the frontier orbital theory, the interaction energy of Benzohydroxamic acid and salicylic hydroxamic acid and cassiterite (100) surface is compared from the energy point of view, and the essence of hydroxamic acid can be used in the flotation of cassiterite.
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表 1 锡石不同解理面的表面能
Table 1. The surface energy of the different dissociation surfaces
晶面指数 表面能/(J·m-2) 100 0.082 010 0.082 001 0.126 011 0.085 101 0.085 110 0.099 111 0.120 表 2 锡石晶体电子结构及铅离子对锡石(100)表面电子结构的影响
Table 2. The electronic structure of cassiterite crystals and the influence of lead ions on the electronic structure of cassiterite (100) surface
矿物 元素 s/e p/e d/e 电子数/e 电荷/e 锡石晶体 Sn 0.88 1.08 10 11.96 2.04 O 1.87 5.15 0 7.02 -1.02 锡石(100)面 Sn 0.99 1.05 10 12.04 1.96 O 1.93 5.01 0 6.94 -0.94 铅活化 Pb 1.81 1.55 9.99 13.35 0.65 Sn 1.47 1.31 10 12.77 1.23 O 1.93 4.97 0 6.90 -0.90 表 3 锡石铅活化前后和羟肟酸前线轨道能量分析
Table 3. Frontier orbital energy analysis before and after activation of cassiterite (100) surface
矿物/药剂 前线轨道 轨道能量/eV ΔE1/eV ΔE2/eV 锡石 HOMO -21.567 LUMO -21.507 铅活化 HOMO -21.133 LUMO -20.972 苯甲羟肟酸 HOMO -5.567 15.946 17.015 LUMO -4.552 15.411 16.581 水杨羟肟酸 HOMO -5.749 15.758 16.633 LUMO -4.934 15.223 16.199 ΔE1=|E(HOMO-reagent)-E(LUMO-mineral)|; ΔE2=|E(HOMO-mineral)-E(LUMO-reagent)|。 -
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