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| Adsorption and transport characteristics of Mn（Ⅱ）/Cd（Ⅱ）by surface sediments in the upper reaches of the Hanjiang River |
| Received:July 03, 2024 |
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| KeyWord:sediment;Mn（Ⅱ）/Cd（Ⅱ）;adsorption experiment;Hydrus-1D |
| Author Name | Affiliation | E-mail | | LI Pengfei | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China | | | YANG Chan | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China | | | SONG Fengmin | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China
Qinba Mountains of Bio-Resource Collabarative Innovation Center of Southern Shaanxi University of Technology, Hanzhong 723001, China | Sfm3297@163.com | | ZHAO Hanghang | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China
Qinba Mountains of Bio-Resource Collabarative Innovation Center of Southern Shaanxi University of Technology, Hanzhong 723001, China | | | LI Qiaoyun | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China | | | QI Wenbo | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China | | | LIU Zhifeng | School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China
1. School of Chemical & Environment Science, Shaanxi University of Technology, Hanzhong 723001, China | |
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| Abstract: |
| In order to study the adsorption and migration characteristics of Mn（Ⅱ）/Cd（Ⅱ）in the sediments of the upper reaches of the Hanjiang River, the surface sediment samples were collected from a mainstream section of the upper reaches of the Hanjiang River. Theadsorption and migration characteristics of Mn（Ⅱ）/Cd（Ⅱ）in the sediments were studied by static-dynamic adsorption method and Hydrus-1D software. The results of batch equilibrium adsorption experiments showed that the adsorption performance of sediments on Mn （Ⅱ）/Cd（Ⅱ）was mainly affected by the pH of the solution. As the pH of the solution increased, the adsorption capacity and adsorption rate of sediments on Mn（Ⅱ）/Cd（Ⅱ）increased. When pH=7, the adsorption capacity and adsorption rate of sediments on Mn（Ⅱ）/Cd（Ⅱ） were ideal. In the adsorption process, the adsorption behavior of Mn（Ⅱ）/Cd（Ⅱ）by sediments is more in line with the pseudo-second-order kinetic model, indicating that chemical adsorption plays a major role in the adsorption process of Mn（Ⅱ）/Cd（Ⅱ）. In this model, the correlation coefficient of Mn（Ⅱ）is 0.999 9, and the correlation coefficient of Cd（Ⅱ）is 0.999 5.In addition, the intraparticle diffusion coefficient of Mn（Ⅱ）/Cd（Ⅱ）on sediments was calculated by adsorption capacity and t1/2, and it was found that intraparticle diffusion also played an important role in the adsorption process. The results of column experiments further showed that the migration of heavy metals in sediments was mainly affected by the concentration of heavy metals. With the increase of the concentration of heavy metal solution in the leaching solution, the shorter the time of penetrating the soil column and the completion of migration, the earlier the peak concentration of the effluent reached. The time of Mn（Ⅱ）penetrating the soil column and the completion of migration at different concentrations of 40-300 mg·L-1 decreased gradually, with the shortest of 132 h and 540 h. The time of Cd（Ⅱ）penetrating the soil column and the completion of migration at different concentrations of 50-200 mg·L-1 decreased gradually, with the shortest of 94 h and 556 h. It shows that heavy metal ions are easy to migrate in water sediments, resulting in deeper pollution in water. The results of FT-IR before and after the adsorption of Mn（Ⅱ）/Cd（Ⅱ）by sediments showed that ion exchange, complexation reaction and precipitation reaction were the main mechanisms for the adsorption of Mn（Ⅱ）/Cd（Ⅱ）by sediments. Combined with the results of batch equilibrium adsorption experiments and column experiments, it was confirmed that heavy metal ions were easy to migrate in surface sediments, causing deeper pollution of water bodies. FT-IR and XPS characterization analysis showed that Mn（Ⅱ）/Cd（Ⅱ）precipitated with Fe oxides and carbonates. |
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