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| Predicting the adsorption of arsenate on soils based on the constant capacitance model |
| Received:March 22, 2023 |
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| KeyWord:surface complexation model;As（Ⅴ）;adsorption;constant capacitance model;generalized composite |
| Author Name | Affiliation | E-mail | | XUE Qin | Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | LI Yan | Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | YU Hemin | Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | WANG Yujun | Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | yjwang@issas.ac.cn |
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| Abstract: |
| Adsorption is one of the important processes to control the migration of As in soil. In this study, the constant capacitance surface complexation model （CCM）was used to simulate the adsorption behavior of As（Ⅴ）in soil, and the surface complexation constant of As（Ⅴ） was obtained based on the CCM model. A linear regression model was established for the basic physical and chemical properties of soil（pH, organic matter, calcium carbonate, amorphous iron/aluminum/manganese, and total iron）and the surface complexation constant of As （Ⅴ）to elucidate the main controlling factors of adsorption of As in soil. The results revealed that As （Ⅴ）exhibited different adsorption characteristics in different types of soil at varying pH levels, and the constant capacitance model could simulate the adsorption edge of As（Ⅴ）at different pH values（R2 ranged from 0.71 to 0.96）. Three surface complexation constants of As（Ⅴ）on the soil surface were obtained by fitting the CCM model. The values of lg K1 in most soils were larger than those of lg K2 and lg K3, indicating that the adsorption of As（Ⅴ）in soil was more inclined to form bidentate rather than monodentate complexes. The regression analysis of As（Ⅴ）surface complexation constants and soil properties demonstrated that the As（Ⅴ） surface complexation constants were mainly affected by soil pH and the contents of amorphous Fe and amorphous Mn. To further verify the universality of the above linear model, the surface complexation constants of As（Ⅴ）on different soils was predicted from the soil property data in the literature, and the adsorption capacity of As（Ⅴ）in the literature soil was also predicted using the CCM model. The predicted and measured values in the literature exhibited a good correlation（R2 = 0.71）, indicating that the model had a certain universality. In this study, based on the adsorption behavior of As（Ⅴ）in soils with different properties, the generalized complex method was used to establish a CCM model to describe the adsorption and distribution process of As （Ⅴ）in non-calcareous soils, providing theoretical support for regional soil heavy metal environmental risk prediction. |
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