磷灰石矿物晶体结构及表面吸附行为的密度泛函理论研究

发布时间：2018-06-22 17:44

  本文选题：磷灰石 + 密度泛函理论　； 参考：《贵州大学》2016年硕士论文

【摘要】：作为一种重要的不可再生资源,磷灰石的综合回收利用是自然界中磷循环的重要组成部分。然而天然磷矿石在形成过程中常常和其他脉石矿物共生或伴生,例如,石英、白云石、方解石等。这些矿物与磷灰石的物理、化学性质接近,且在形成过程中嵌布复杂,难以分离,因此长期以来磷矿的分选一直困扰着人们。目前浮选被认为是分离磷矿石中有价磷资源最有效的方法之一,然而浮选工艺常常受制于浮选药剂,同时常规浮选药剂带来的生态问题也是磷矿石分选工作不得不面对的问题。因此,探索磷矿石浮选绿色高效的浮选药剂已迫在眉睫。本论文基于密度泛函理论(DFT)的第一性原理,研究了两种磷灰石的晶体结构和表面浮选行为机理。考察了氟磷灰石和氯磷灰石体相及(001)面的结构及电子性质;重点研究了两种磷灰石浮选过程中水分子和捕收剂的作用机理。主要研究结果如下:1.氟磷灰石和氯磷灰石的禁带宽度分别为5.667 eV和5.154 eV,两种磷灰石的态密度分布的差异主要显示在通道原子。相对于F,Cl的能带整体移向高能级方向,其3s和3p态均较F 2s和2p能级高,且Cl 3p态更宽,更接近费米能级,即氯磷灰石稳定性不如氟磷灰石。研究表明,F得电荷能力强于Cl,对应F 2s和2p态荷电分别是1.96 e、5.72 e;Cl 3s和3p态得电荷分别是1.94 e和5.65 e。两种磷灰石中的O—P长度接近,但是氟磷灰石的F—Ca结合作用明显强于氯磷灰石的Cl—Ca作用,同时氯磷灰石中的O—Ca较氟磷灰石的短。进一步研究显示O—P具有较强的化合键性质,对应原子间作用也最强;F—Ca、O—Ca和Cl—Ca呈现更多的离子性,且键长更长。2.氟磷灰石的Ca终端面和氯磷灰石的Ca-Cl终端面分别为对应表面能最小的终端面,其值分别为3.86 eV/cell和3.72 e V/cell。弛豫分析显示,这几种终端面中位于独立层的Ca原子表现出较大的位移,但位移仍不足以引起表面原子的重构。进一步研究显示氟磷灰石的Ca终端面和氯磷灰石的Ca-Cl和Ca终端面的性质更接近于各自的体相。3.氟磷灰石的F-A构型吸附能最大,对应值为-69.541 kJ/mol;最小的是F-B构型,对应值为-123.817 kJ/mol。氯磷灰石的最大值为Cl-A构型,其值为-67.033kJ/mol;最小值为Cl-D构型的-118.996 kJ/mol。态密度分析显示,单个水分子在两种磷灰石表面的吸附对其表面性质产生了一定的影响,这种作用主要表现为物理作用。单层水分子膜吸附研究显示,水分子在磷灰石表面的作用呈现出一种有规律的无序排列。4.捕收剂(CH_3(CH)_2COO)分子在磷灰石(001)面的吸附只存在一种构型,即在最外层的Ca1位点,对应氟磷灰石(001)面和氯磷灰石(001)面的吸附能分别是-137.515 kJ/mol和-134.733 kJ/mol。Mulliken电荷布居显示,吸附后捕收剂末端O86与Ca6的影响最为明显。Mulliken键布居显示捕收剂分子在磷灰石表面吸附后,原来围绕在Ca1位点的O被弹开,Ca—O变长,即药剂分子在磷灰石表面的作用时一个排开水分子吸附的过程。进一步研究显示,Ca6与O75、O77、O78的作用被削弱;捕收剂末端O86与Ca6在临近费米能级附近存在较强的成键作用。
[Abstract]:As an important non renewable resource, the comprehensive recovery and utilization of apatite is an important part of the phosphorus cycle in nature. However, the natural phosphate rock is often associated with or associated with other gangue minerals, such as quartz, dolomite, calcite, etc., such as quartz, dolomite, calcite, etc.. These minerals are closely related to the physical and chemical properties of apatite and are in shape. It is complicated and difficult to separate in the process of formation, so the separation of phosphate rock has been perplexing people for a long time. Flotation is considered as one of the most effective methods to separate phosphorus resources from phosphate rock. However, flotation process is often controlled by flotation reagents. At the same time, the ecological problem brought by conventional flotation reagents is also not necessary for the separation of phosphate rock. Therefore, it is imminent to explore the flotation reagent of green and efficient flotation of phosphate rock. Based on the first principle of density functional theory (DFT), the crystal structure and surface flotation behavior mechanism of two kinds of apatite are studied. The structure and electronic properties of fluorapatite and chlorapatite body phase and (001) surface are investigated. The mechanism of water molecules and collector in the flotation process of two kinds of apatite is studied. The main results are as follows: the forbidden band width of 1. fluorapatite and chlorapatite is 5.667 eV and 5.154 eV respectively. The difference of the density distribution of the two apapatite is mainly shown in the channel atom. Relative to F, the energy band of the Cl is shifted to the high energy level, and its 3S The 3P state and the 3P state are higher than the F 2S and 2p energy levels, and the Cl 3P state is wider and closer to the Fermi level, that is, the stability of the chlorapatite is not as good as the fluorapatite. The study shows that the charge capacity of F is stronger than that of Cl, and the corresponding F 2S and 2p state charge are 1.96 e, 5.72 respectively. The binding effect of F - Ca of limestone is stronger than the Cl - Ca effect of chlorapatite, while O - Ca in chlorapatite is shorter than that of fluorapatite. Further studies show that O P has strong bonding properties and the interaction between atoms is also the strongest. F Ca, O Ca and mercury are more ionic, and the bond length is longer. The Ca-Cl terminal surface of the surface and chlorapatite is the terminal surface with the smallest corresponding surface energy, respectively, the values of 3.86 eV/cell and 3.72 e V/cell. relaxation analysis show that the Ca atoms in the independent layer show a larger displacement in these terminal surfaces, but the displacement is still not enough to cause the reconstruction of the surface proon. Further research shows the C of the fluorapatite. The properties of Ca-Cl and Ca terminal surfaces of a end faces and chlorapatite are much closer to the F-A configuration of.3. fluorapatite in their respective body phases, the corresponding values are -69.541 kJ/mol, the smallest is F-B configuration, and the maximum value of -123.817 kJ/mol. chlorapatite is Cl-A configuration. J/mol. state density analysis shows that the adsorption of single water molecules on the surface of two apatite has a certain effect on its surface properties. This effect is mainly physical. The study of monolayer water molecular membrane adsorption shows that the action of water molecules on the apatite surface presents a regular disordered arrangement of.4. collector (CH_3 (CH) _2COO). There is only one configuration in the adsorption of apatite (001) surface, that is, at the outermost Ca1 site, the adsorption energy for the fluorapatite (001) surface and the chlorapatite (001) surface is -137.515 kJ/mol and -134.733 kJ/mol.Mulliken, respectively. The influence of O86 and Ca6 at the end of the collector is most obvious after the adsorption of.Mulliken bond. After the adsorbents were adsorbed on the apatite surface, the O was opened around the Ca1 site, and the Ca - O became longer, that is, the adsorption process of the molecules on the apatite surface. Further studies showed that the effects of Ca6 and O75, O77, O78 were weakened, and the terminal O86 and Ca6 were strong near the near Fermi level. Bonding.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD97
，

本文编号：2053644