高等学校化学学报

高等学校化学学报 ›› 2013, Vol. 34 ›› Issue (7): 1673.doi: 10.7503/cjcu20130024

• 物理化学 • 上一篇    下一篇

PFOS在锐钛型TiO2表面吸附行为的理论研究

薛倩倩1, 何广智2, 夏树伟1, 潘纲2   

  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, 青岛 266100;
    2. 中国科学院生态环境研究中心, 环境纳米材料研究室, 北京 100085
  • 收稿日期:2013-01-08 出版日期:2013-07-10 发布日期:2013-06-21
  • 通讯作者: 夏树伟, 女, 博士, 教授, 博士生导师, 主要从事界面理论化学及构效关系研究. E-mail: shuweixia@ouc.edu.cn E-mail:shuweixia@ouc.edu.cn;gzhhe@rcees.ac.cn
  • 基金资助:

    国家自然科学基金(批准号: 20677053)及环境水质学国家重点实验室专项经费(批准号: 11Y06ESPCR)资助.

Theoretical Studies on Adsorption of PFOS on Anatase TiO2 Surfaces

XUE Qian-Qian1, HE Guang-Zhi2, XIA Shu-Wei1, PAN Gang2   

  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, China;
    2. Department of Environmental Nano-materials, Research Center for Eco-environmental Science, Chinese Academy of Sciences, Beijing 100085, China
  • Received:2013-01-08 Online:2013-07-10 Published:2013-06-21
  • Contact: Shu-Wei XIA E-mail:shuweixia@ouc.edu.cn;gzhhe@rcees.ac.cn

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摘要：

采用密度泛函理论(DFT)B3LYP方法对全氟辛烷磺酸(PFOS)在锐钛型TiO2表面的化学吸附和物理吸附行为进行了研究, 其中化学吸附包含双齿双核(BB)和单齿单核(MM)在内的4种可能的吸附构型. 吸附能(Eads)及反应吉布斯自由能(ΔGads)的计算结果表明, PFOS分子易于与TiO2表面发生氢键作用吸附; 化学吸附表现为PFOS分子与TiO2表面的水分子(H2O)和羟基(-OH)反应, 且与取代-OH相比, H2O取代相对更容易发生, 其中, MM1构型(取代一个表面水分子)为化学吸附中的优势构型. PFOS在锐钛矿表面吸附的热力学稳定性和反应自发性顺序如下: H-Bonded(氢键吸附)>MM1(取代一个表面水分子)>BB1(取代两个表面水分子)>MM2(取代一个表面羟基)>BB2(取代一个表面水分子和一个表面羟基). 成键结构分析表明, TiO2表面H2O/-OH官能团与PFOS上的磺酸基之间形成了中等强度的氢键; 在化学吸附过程中, 电荷从PFOS分子向TiO2表面发生转移, 生成Ti—O—S化学键, 电荷转移主要来自PFOS分子的O和F原子.

关键词: 密度泛函理论, 全氟辛烷磺酸, 锐钛矿, 吸附结构

Abstract:

Adsorption behavior of perfluorooctane sulfonate(PFOS) on anatase TiO2 surfaces was studied with DFT-B3LYP method. Physisorption including hydrogen-bond interaction and chemi-adsorption including bidentate binuclear(BB) and monodentate mononuclear(MM) complexes were investigated in the study. Calculations of adsorption energy(Eads) and Gibbs free energy(ΔGads) showed that physisorption was easier tooccur. Chemi-adsorption surface complexes were produced by reaction between PFOS and surface water(H2O) or hydroxyl(-OH), and the reaction to replace H2O was easier than that to replace -OH group. MM1(reacted with one H2O of surface) surface complex was the most thermodynamically favorable chemi-adsorption mode. The thermodynamically favorable and stability order of PFOS adsorbed on anatase TiO2 surfaces was H-bonded(hydrogen bonded adsorption)>MM1(reacted with one H2O of surface)>BB1(reacted with two H2O of surface)>MM2(reacted with one -OH of surface)>BB2(reacted with one H2O and one -OH of surface). Results of bond length analysis indicated that the interaction between H2O/-OH function group on TiO2 surface and sulfonate group in PFOS resulted in the formation of moderate intensity hydrogen bond. Charges transferred from PFOS molecule to TiO2 surface during chemi-adsorption process, leading to the formation of Ti—O—S bond, and transfered electrons in the process were mainly from strong electronegative atoms O and F.

Key words: Density functional theory, Perfluorooctane sulfonate, Anatase, Adsorption structure

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