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首页> 外文会议>Global Symposium on Recycling, Waste Treatment and Clean Technology; 20040926-29; Madrid(ES) >DIFFERENTIAL COMPLEXATION OF Zn~(2+) AND Cd~(2+) TO FULVIC ACID IN WATER
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DIFFERENTIAL COMPLEXATION OF Zn~(2+) AND Cd~(2+) TO FULVIC ACID IN WATER

机译：Zn〜（2+）和Cd〜（2+）与水中富叶酸的微分络合

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摘要

As complexants of metallic ions in soil and water, aquatic and terrestrial fulvic (FA) and humic acids (HA), deriving from the solubilization of organic matter are environmentally significant pollution transporters and bioavailability agents. Cadmium ions are important natural water pollutants, occurring in zinc metallurgy and in electroplating liquid wastes, as cadmium is always associated to zinc in nature, by isomorphic substitution in its compounds. In this paper, a study of complexes formed by Zn~(2+) and Cd~(2+) with fulvic acids, using computational chemistry is presented. The relative free energy calculations on a thermodynamic cycle were carried out using Free Energy Perturbation (FEP) and Density Functional Theory (DFT-B3LYP/6-31G~(**)) methods. The computed interaction energies between orbitals from Natural Bond Order (NBO) calculations showed that Cd-FA complexes, octahedral with four water molecules in the coordination sphere, are more stable than Zn-FA complexes, tetrahedral with two water molecules. Consequently, FA should be a more efficient ligand for Cd~(2+) bioavailability and toxicity in natural aquatic environments.
机译：作为金属离子在土壤和水中，腐殖酸和腐殖酸（HA）和腐殖酸（HA）在土壤和水中的络合剂，它们是对环境具有重大影响的污染物转运剂和生物利用度试剂。镉离子是重要的天然水污染物，它存在于锌冶金和电镀废液中，因为镉在自然界中总是通过其同构取代而与锌缔合。本文利用计算化学方法研究了Zn〜（2+）和Cd〜（2+）与黄腐酸形成的配合物。使用自由能扰动（FEP）和密度泛函理论（DFT-B3LYP / 6-31G〜（**））方法进行热力学循环的相对自由能计算。根据自然键序（NBO）计算得出的轨道之间的相互作用能表明，在配位球中具有四个水分子的八面体Cd-FA配合物比具有两个水分子的四面体的Zn-FA配合物更稳定。因此，FA应该是天然水生环境中Cd〜（2+）生物利用度和毒性的更有效配体。

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