Analysis of ion binding on humic substances and the determination of intrinsic affinity distributions.
Analysis of ion binding on humic substances and the determination of intrinsic affinity distributions.
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分析腐殖质上的离子结合并确定内在亲和力分布。
DOI：
10.1016/s0003-2670(00)81235-0
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发表时间：
1990
影响因子：
6.2
通讯作者：
L. Koopal
中科院分区：
文献类型：
--
作者：
J. Wit;W. H. Riemsdijk;M. Nederlof;D. Kinniburgh;L. Koopal
腐殖物质的特征在于可变的电势和导致化学异质性的各种结合位点。离子与这些物质的结合受到这两个因素的影响。一种基于酸碱滴定在几个盐水平的方法，允许适当的静电双层模型和固有的质子亲和力分布的评估。双层模型用于将每个数据点的pH值转换为pHS，其中HS是结合位点附近扩散层中的质子浓度。它示出，与一个适当的双层模型的质子结合曲线在不同的盐水平收敛到一个“主曲线”时，绘制为pHS的函数。然后可以使用LOGA方法从“主曲线”导出固有质子亲和力分布。严格分析腐殖物质与金属的结合是复杂的，在实践中是不可行的。在两个不同的（简化）假设，即完全耦合和非耦合结合，它示出了如何可以获得内在的金属离子的亲和力分布。模型计算表明，表观金属离子的亲和力分布不类似的内在金属离子的亲和力分布。
Humic substances are characterized by a variable electric potential and by a variety of binding sites leading to chemical heterogeneity. Binding of ions to these substances is influenced by both factors. A methodology based on acid—base titrations at several salt levels is presented that allows for the assessment of an appropriate electrostatic double-layer model and the intrinsic proton affinity distribution. The double-layer model is used for the conversion of pH to pHSfor each data point, where HSis the proton concentration in the diffuse layer near the binding site. It is shown that with an appropriate double-layer model the proton binding curves at different salt levels converge into one “master curve” when plotted as a function of pHS. The intrinsic proton affinity distribution can then be derived from the “master curve” using the LOGA method. A rigorous analysis of metal binding to humic substances is complex and in practice is not feasible. Under two different (simplifying) assumptions, namely fully coupled and uncoupled binding, it is shown how intrinsic metal ion affinity distributions can be obtained. Model calculations show that apparent metal ion affinity distributions do not resemble the intrinsic metal ion affinity distribution.