Analysis of copper binding in the ternary system Cu2+/humic acid/goethite at neutral to acidic pH.
Analysis of copper binding in the ternary system Cu2+/humic acid/goethite at neutral to acidic pH.
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DOI：
10.1021/es0500308
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发表时间：
2005-05
影响因子：
11.4
通讯作者：
Takumi Saito;L. Koopal;S. Nagasaki;Satoru Tanaka
中科院分区：
文献类型：
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作者：
Takumi Saito;L. Koopal;S. Nagasaki;Satoru Tanaka
重金属和锕系元素离子与天然胶体如腐殖物质和金属氧化物的结合在这些离子的生态毒理学行为中起着重要的作用。已经构建了几个热力学模型来预测这些离子在金属/HS或金属/氧化物二元体系中的形态。然而，在自然环境中，HS在氧化物上的吸附会影响目标金属的结合，导致偏离校准的二元模型的加和性。在这项研究中，铜（Cu 2+）的纯化奥德里奇腐殖酸（PAHA）/针铁矿复合物在中性到酸性pH值区域的结合进行了研究，通过测量Cu 2+结合等温线。测得的等温线进行了比较，在类似的条件下，获得的二元系统的结果。比较结果表明，在三元体系中的Cu 2+结合相对于在相应的二元体系中的Cu 2+结合的总和是增强的。从PAHA的荷电行为以及PAHA/针铁矿界面附近的涂抹电位曲线分析，Cu 2+与配合物结合的增加主要归因于质子对PAHA吸附官能团的竞争减少和针铁矿表面附近的静电势变化。
Binding of heavy metal and actinide ions to natural colloids, such as humic substances (HSs) and metal (hydr)-oxides, plays an important role in the ecotoxicological behavior of these ions. Several thermodynamic models have been constructed to predict the speciation of these ions in metal/HS or metal/oxide binary systems. However, in natural environments the adsorption of HSs on oxides can influence the binding of target metals, leading to deviation from the additivity of calibrated binary models. In this study binding of copper (Cu2+) to the purified Aldrich humic acid (PAHA)/goethite complex in the neutral to acidic pH region was investigated by measuring Cu2+ binding isotherms. The measured isotherms were compared with the results obtained for the binary systems under similar conditions. The comparison revealed that Cu2+ binding in the ternary system is enhanced with respect to the sum of Cu2+ binding in the corresponding binary systems. From the analysis of the charging behavior of the adsorbed PAHA as well as the smeared-out potential profile near the PAHA/goethite interface, the increase of Cu2+ binding to the complex was mainly attributed to the decrease of proton competition to the functional groups of the adsorbed PAHA and the change of the electrostatic potential in the vicinity of the goethite surface.