The objective of this study was to predict the competitive adsorption of As(III), As(V), and PO₄ by an iron oxide impregnated carbon (L-Act, 9% Fe(III) amorphous iron oxide) over a range of environmental conditions using the surface complexation modeling (SCM) approach. L-Act surface complexation constants determined from a single pH-adsorption edge were used to predict pH-dependent competitive removal in singular, binary, and tertiary adsorbate systems. As(III), As(V), and PO₄ complexes were modeled as bidentate binuclear species at low pH and monodentate species at high pH using the two monoprotic surface site/diffuse electric double layer model (2MDLM). F values determined based on 2MDLM predictions were close to those calculated by FITEQL (a statistical optimization program) demonstrating the effectiveness of the 2MDLM in describing adsorption behavior. F values were generally in the recommended range of 0.1–20 indicating a good fit between the data and the model. The 2MDLM also successfully predicted As(III)/As(V)/PO₄ adsorption data of hydrous ferric oxide and goethite adsorbents from the literature.

中文翻译：

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氧化铁浸渍活性炭对As（III），As（V）和PO 4的竞争性吸附：表面复合物建模

这项研究的目的是预测氧化铁浸渍碳（L-Act，9％Fe（III）无定形氧化铁）在下列条件下的竞争性吸附As（III），As（V）和PO ₄的能力。使用表面络合建模（SCM）方法的环境条件。从单个pH吸附边缘确定的L-Act表面络合常数用于预测单，二元和三级吸附物系统中pH依赖的竞争性去除。使用两个单质子表面位点/扩散双电层模型（2MDLM）将As（III），As（V）和PO ₄络合物建模为低pH下的双齿双核物种和高pH下的单齿双物种。F基于2MDLM预测确定的值接近于FITEQL（统计优化程序）计算出的值，表明2MDLM在描述吸附行为方面的有效性。F值通常在0.1–20的建议范围内，表明数据与模型之间具有良好的拟合度。2MDLM还成功地从文献中预测了含水氧化铁和针铁矿吸附剂的As（III）/ As（V）/ PO ₄吸附数据。