物理化学学报 >> 2014, Vol. 30 >> Issue (5): 829-835.doi: 10.3866/PKU.WHXB201403211

理论与计算化学 上一篇    下一篇

水合Pb(OH)+在高岭石(001)晶面的吸附机理

王娟1,2, 夏树伟1, 于良民1   

  1. 1 中国海洋大学化学化工学院, 海洋化学理论与工程技术教育部重点实验室, 山东青岛266100;
    2 青岛农业大学化学与药学院, 山东青岛266109
  • 收稿日期:2014-01-21 修回日期:2014-03-20 发布日期:2014-04-25
  • 通讯作者: 夏树伟 E-mail:shuweixia@ouc.edu.cn
  • 基金资助:

    国家自然科学基金(20677053)和山东省自然科学基金(ZR2012CQ015)资助项目

Adsorption Mechanism of Hydrated Pb(OH)+ on the Kaolinite (001) Surface

WANG Juan1,2, XIA Shu-Wei1, YU Liang-Min1   

  1. 1 Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, Shandong Province, P. R. China;
    2 College of Chemistry and Pharmacy, Qingdao Agricultural University, Qingdao 266109, Shandong Province, P. R. China
  • Received:2014-01-21 Revised:2014-03-20 Published:2014-04-25
  • Contact: XIA Shu-Wei E-mail:shuweixia@ouc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20677053) and Natural Science Foundation of Shandong Province, China (ZR2012CQ015).

摘要:

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.

关键词: Pb(OH)+, 高岭石, 化学吸附, 密度泛函理论, 配位数O641

Abstract:

The adsorption behavior of Pb(OH)+ on the basal octahedral (001) surface of kaolinite has been investigated using the Perdew-Burke-Ernzerhof generalized gradient approximation (GGA-PBE) of density functional theory with periodic slab models, where the water environment was considered. The coordination geometry, coordination number, preferred adsorption position, and adsorption type were examined, with binding energy estimated. All the monodentate and bidentate complexes exhibited hemi- directed geometry with coordination numbers of 3-5. Site of "Ou" with "up" hydrogen was more favorable for monodentate complex than site of "Ol" with "lying" hydrogen. Monodentate complexation of "Ou" site with a high binding energy of -182.60 kJ·mol-1 should be the most preferred adsorption mode, while bidentate complexation on "OuOl" site of single Al center was also probable. The stability of adsorption complex was found closely related to the hydrogen bonding interactions between surface Ol and H in aqua ligands of Pb(Ⅱ). Mulliken population and density of states analyses showed that coupling of Pb 6p with the antibonding Pb 6s―O 2p states was the primary orbital interaction between Pb(Ⅱ) and the surface oxygen. Hydrogen complexation occupied a much large proportion in the joint coordination structure of bidentate complex, where bonding state filling predominated for the Pb―Ol interaction.

Key words: Pb(OH)+, Kaolinite, Chemical adsorption, Density functional theory, Coordination number

MSC2000: 

  • O647