Competitive Adsorption of As(III), As(V), and PO4 by an Iron Oxide Impregnated Activated Carbon: Surface Complex Modeling
2020
Ngantcha-Kwimi, T Angele | Reed, Brian E.
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.
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