Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment , Northwest A&F University , Yangling 712100 , China.
Xinjiang Technical Institute of Physics & Chemistry , Chinese Academy of Sciences , Urumqi 830011 , China.
Environ Sci Technol. 2018 May 15;52(10):5725-5733. doi: 10.1021/acs.est.8b00425. Epub 2018 Apr 24.
This paper presents the transformation of PAHs (phenanthrene, anthracene, benzo[a]anthracene, pyrene, and benzo[a]pyrene) on montmorillonite clays that are modified by transition-metal ions [Fe(III), Cu(II), Ni(II), Co(II), or Zn(II)] at room temperature (∼23 °C). The decay of these PAHs follows first-order kinetics, and the dependence of the observed rate constants ( k, day) on the presence of metal ions follows the order Fe(III) > Cu(II) > Ni(II) > Co(II) > Zn(II). The values of k show reasonable linear relationships with the oxidation potentials of the PAHs and the redox potentials of the metal ions. Notably, transformation of these PAHs results in the formation of environmentally persistent free radicals (EPFRs), which are of major concern due to their adverse effects on human health. The potential energy surface (PES) calculations using density functional theory were performed to understand the trends in k and the plausible mechanisms for radical formation from the PAHs on modified clays. The yields and stability of these EPFRs from anthracene and benzo[a]pyrene on clay surfaces varies with both the parent PAH and the metal ion. The results demonstrated the potential role of metals in the formation and fate of PAH-induced EPFR at co-contaminated sites.
本文研究了在室温（约 23°C）下，用过渡金属离子[Fe(III)、Cu(II)、Ni(II)、Co(II)或 Zn(II)]修饰后的蒙脱石粘土上多环芳烃（PAHs，包括菲、蒽、苯并[a]蒽、芘和苯并[a]芘）的转化。这些 PAHs 的降解遵循一级动力学，观察到的速率常数（k，天）随金属离子的存在而变化的顺序为 Fe(III) > Cu(II) > Ni(II) > Co(II) > Zn(II)。k 值与 PAHs 的氧化电位和金属离子的氧化还原电位呈合理的线性关系。值得注意的是，这些 PAHs 的转化会形成环境持久性自由基（EPFRs），由于其对人类健康的不利影响，EPFRs 引起了广泛关注。使用密度泛函理论进行了势能面（PES）计算，以了解 k 的趋势以及从改性粘土上的 PAHs 形成自由基的可能机制。粘土表面上的蒽和苯并[a]芘形成的这些 EPFRs 的产率和稳定性随母体 PAH 和金属离子的变化而变化。结果表明，金属在多环芳烃诱导的 EPFR 在共污染位点的形成和命运中可能发挥作用。
