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采用密度泛函理论广义梯度近似平面波赝势法,结合周期平板模型,探讨了水体环境中Pb(OH)+在高岭石铝氧八面体(001)晶面的吸附行为和机理,确定了吸附配合物的结构、配位数、优势吸附位和吸附类型.结果表明,Pb(II)与高岭石铝氧(001)面的氧原子形成单齿或双齿配合物,其配位数为3-5,均为半方位构型.高岭石表面存在含“平伏”氢原子的表面氧(Ol)位和含“直立”氢原子的氧(Ou)位,后者更易与Pb(OH)+单齿配位,该吸附配合物具有较高的结合能(-182.60 kJ·mol-1),为优势吸附物种;高岭石表面位于同一个Al原子上的“OuOl”位可形成双齿配合物.表面Ol与水分子配体形成氢键,对配合物的稳定性起到关键作用.Mulliken布居和态密度分析表明,高岭石单齿配合物中Pb―O成键机理主要为Pb 6p轨道与Pb 6s―O 2p反键轨道进行耦合,电子转移到反键轨道.双齿配合物“Pb―Ol―H”共配位结构中,受配位氢原子影响,Pb―Ol成键过程成键态电子填充占主导地位.
The adsorption behavior and mechanism of Pb (OH) + on kaolinite octahedra (001) surface in water environment were investigated by using density functional theory (GPD) generalized gradient approximation plane wave pseudopotential method and periodic plate model. The adsorption The results show that the oxygen atoms of Pb (II) and kaolinite Al (001) surface form monodentate or bidentate complexes with the coordination number of 3-5, all in the semi-azimuthal configuration, there are surface oxygen (O1) sites on the surface of kaolinite with “flat ” hydrogen atoms and oxygen sites containing “upright ” hydrogen atoms The complex has a higher binding energy (-182.60 kJ · mol-1) with Pb (OH) + monodentate, which is the dominant adsorbed species. The surface of kaolinite is located on the same Al atom “, Which can form a bidentate complex. The surface Ol formed hydrogen bond with the water molecule ligand, which played a key role in the stability of the complex. Mulliken population density and state density analysis showed that the monopolar composition of kaolinite Pb -O bond mechanism mainly for the Pb 6p orbital and Pb 6s-O 2p antibonding orbital coupling, electron transfer to the antibonding orbital. ”Bipodal complexes “ Pb-Ol-H ”co- Bit Hydrogen atoms, Pb-Ol bonding process electronic bonding dominates.