Metal ion binding by humic acid: Application of the NICA-Donnan model
Metal ion binding by humic acid: Application of the NICA-Donnan model
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DOI：
10.1021/es950695h
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发表时间：
1996-05-01
影响因子：
11.4
通讯作者：
VanRiemsdijk, WH
中科院分区：
文献类型：
--
作者：
Kinniburgh, DG;Milne, CJ;VanRiemsdijk, WH
将Donnan型电解质离子非特异性结合模型与非理想竞争吸附(NICA)特异性结合模型相结合，得到了腐殖质离子结合模型。该模型考虑了场地的异质性、非理想性、多组分竞争和静电相互作用。泥炭腐植酸与H、Ca、Cd、Cu、Pb的结合符合Nica-Donnan模型。模型拟合度较好，涵盖了较宽的pH和游离金属浓度范围。然后使用这些单一金属数据集的参数来预测在不同pH下钙对Cd和Cu结合的竞争效应。这些预测与实验数据吻合得很好，尽管有一些小的但系统的差异。新的Nica-Donnan模型也很好地预测了从0.1M KNO_3背景电解液到0.01M KNO_3时Cd和Cu结合的增加。该模型的一个缺点是，在某些情况下，它严重低估了H+/M(2+)交换比，特别是在高pH和铜结合时。
A Donnan-type model for nonspecific binding of electrolyte ions has been combined with the nonideal competitive adsorption (NICA) model for specific binding to produce a model for ion binding to humic substances. The model considers site heterogeneity, non-ideality, multicomponent competition, and electrostatic interactions. The NICA-Donnan model was fitted to data for H, Ca, Cd, Cu, and Pb binding by a purified peat humic acid. The model fits were good and covered a wide range of pH and free metal concentrations. The parameters from these single metal data sets were then used to predict the competitive effect of Ca on Cd and Cu binding at various pHs. These predictions agreed well with the experimental data although there were some small but systematic differences. The new NICA-Donnan model also predicted reasonably well the increase in Cd and Cu binding on changing from a 0.1 M KNO3 background electrolyte to 0.01 M KNO3. A shortcoming of the model is that in some cases it significantly underestimated the H+/M(2+) exchange ratio, especially at high pH and for Cu binding.