Application of the surface complexation concept to complex mineral assemblages
Application of the surface complexation concept to complex mineral assemblages
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DOI：
10.1021/es980312q
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发表时间：
1998-10-01
影响因子：
11.4
通讯作者：
Fuller, CC
中科院分区：
文献类型：
--
作者：
Davis, JA;Coston, JA;Fuller, CC
说明了用于描述水环境中无机污染物吸附的两种类型的建模方法：(a) 组分加和方法和 (b) 广义复合方法。每种方法均用于模拟从马萨诸塞州开普戈德含水层收集的特征明确的沉积物对 Zn2+ 的吸附。在实验室批量实验中研究了沉积物对 Zn2+ 的吸附，并选择了一系列 pH 值和 Zn(II) 浓度以涵盖含水层中观察到的条件。在广义复合方法中，使用 FITEQL 通过实验数据校准一位点和两位点表面络合模型参数。模拟 Zn2+ 吸附的 pH 依赖性，无需明确表示静电能项。模型中也不需要表面酸度常数和主要电解质离子形成的离子对，从而最大限度地减少了拟合参数的数量。在不操纵表面积或位点密度参数值的情况下，使用组分加和模型方法预测 Zn2+ 吸附并不能充分模拟实验数据。为了将组分加和方法应用于环境吸附剂，需要进一步研究以更好地表征沉积物表面涂层的组成。广义复合建模方法需要较少的信息，并且可以被视为更适合在溶质输运模型中应用。只需三个可调参数，该方法就可以模拟一系列化学条件下的 Zn2+ 吸附，这些化学条件会导致含水层内 Zn2+ 的分配系数 (Kd) 发生几个数量级的变化。
Two types of modeling approaches are illustrated for describing inorganic contaminant adsorption in aqueous environments: (a) the component additivity approach and (b) the generalized composite approach. Each approach is applied to simulate Zn2+ adsorption by a well-characterized sediment collected from an aquifer at Cape God, MA. Zn2+ adsorption by the sediment was studied in laboratory batch experiments with a range of pH and Zn(ll) concentrations selected to encompass conditions observed in the aquifer. In the generalized composite approach, one- and two-site surface complexation model parameters were calibrated with the experimental data using FITEQL. The pH dependence of Zn2+ adsorption was simulated without exp licit representation of electrostatic energy terms. Surface acidity constants and ion pair formation by major electrolyte ions were also not required in the model, thereby minimizing the number of fitted parameters. Predictions of Zn2+ adsorption with the component additivity modeling approach did not simulate the experimental data adequately without manipulation of surface area or site density parameter values. To apply the component additivity approach to environmental sorbents, further research is needed to better characterize the composition of sediment surface coatings. The generalized composite modeling approach requires less information and can be viewed as more practical for application within solute transport models. With only three adjustable parameters, this approach could simulate Zn2+ adsorption over a range of chemical conditions that would cause several orders of magnitude variation in the distribution coefficient (Kd) for Zn2+ within the aquifer.