Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States.
Environ Sci Technol. 2011 Apr 15;45(8):3202-9. doi: 10.1021/es102408w. Epub 2010 Nov 18.
An a priori model of metal complexation by natural organic matter (NOM) has previously been shown to predict experimental data at pH 7.0 and 0.1 M ionic strength (Cabaniss, S. E. Environ. Sci. Technol. 2009). Unlike macroscopic models based only on stoichiometry and thermodynamics, this a priori model also predicts the ligand groups and properties of complexed (occupied) molecules. Ligand molecules with strong binding sites form complexes at low metal concentrations and have average properties (molecular weight, charge, aromaticity) which can differ significantly from the average properties of bulk NOM. Cu(II), Ni(II) and Pb(II) preferentially bind to strong amine-containing sites which are often located on small (MW < 1000), lower-aromaticity molecules. Cd(II) and Zn(II) show generally weaker binding, although they also prefer amine-containing sites to pure carboxylates and bind to smaller, less aromatic molecules. Ca(II) shows no real preference for amine over carboxylate ligand groups, preferentially binding to larger and more negatively charged molecules. Al(III) has a unique preference for phenol-containing sites and larger, more aromatic molecules. While some predictions of this model are consistent with a variety of experimental data from the literature, others await validation by molecular-level analysis.
先前已经有研究表明，天然有机物（NOM）与金属络合的先验模型可以在 pH 值为 7.0 和 0.1 M 离子强度条件下预测实验数据。与仅基于化学计量学和热力学的宏观模型不同，该先验模型还可以预测配体基团和络合（占据）分子的性质。具有强结合位点的配体分子在低金属浓度下形成配合物，并且具有的平均性质（分子量、电荷、芳香性）与 NOM 本体的平均性质有很大差异。Cu(II)、Ni(II) 和 Pb(II)优先与强含胺位点结合，这些位点通常位于较小（MW < 1000）、低芳香性的分子上。Cd(II) 和 Zn(II)的结合通常较弱，尽管它们也优先与含胺位点结合而不是纯羧酸盐，并且与较小、低芳香性的分子结合。Ca(II)对胺配体基团没有真正的偏好，优先与较大、带更多负电荷的分子结合。Al(III)对含酚基团和较大、更芳香性的分子具有独特的偏好。虽然该模型的一些预测与文献中的各种实验数据一致，但其他预测有待通过分子水平分析进行验证。
