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Background <p>Lead and cadmium (Pb/Cd) are pervasive in soils, and their detrimental effects on ecosystems are increasingly evident. Therefore, taking measures to mitigate the toxicity of Pb/Cd is urgently necessary. In this study, bentonite was used as a raw material for modification, and the influence of modified bentonite on the soil adsorption and desorption of Pb/Cd was investigated. The potential application of modified bentonite in mitigating the phytotoxicity of Pb/Cd was evaluated by conducting pot experiments, and the environmental risk was evaluated by acid rain leaching test.</p> Results <p>Results indicate that the removal rates of Pb/Cd of BTS obtained by 450℃ calcination and 20% citric acid activation reached 88.03% and 80.04%, respectively. Pb/Cd was primarily adsorbed by BTS through coordination between the groups (e.g., siloxane, hydroxyl, and carboxyl) and Pb/Cd. BTS amendment at an appropriate concentration (1%, 3%, and 5%, w/w) to soils contaminated with Pb/Cd resulted in a significant increase in ryegrass yield and chlorophyll (<i>P</i> &lt; 0.05), and it enhanced root activity and antioxidant enzyme activity. Furthermore, under the effect of acid rain at pH 5.0, the release concentrations of Pb/Cd were the lowest when BTS-5% was added, and the cumulative release concentrations were 2.079 and 1.506 mg·L<sup>−1</sup>, respectively. The extractable acid state increased before and after leaching, whereas the residual state decreased.</p> Conclusion <p>BTS (3% and 5%) can reduce the environmental risk level from a strong risk to a slight risk. Furthermore, the results of this study can provide theoretical basis for the promotion and application of bentonite in pollution control.</p>

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Adsorption and desorption effect of modified bentonite on soil heavy metal Pb/Cd and the feasibility assessment of reducing the ecotoxicity

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年6月21日

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  • Xue Yang,
  • Yuancheng Li,
  • Maoxi Gan,
  • Yuling Chen,
  • Hailong Meng,
  • Lun Li,
  • Jianhong Xu,
  • Meihong Zhao,
  • Dongpeng Lv

摘要

Background

Lead and cadmium (Pb/Cd) are pervasive in soils, and their detrimental effects on ecosystems are increasingly evident. Therefore, taking measures to mitigate the toxicity of Pb/Cd is urgently necessary. In this study, bentonite was used as a raw material for modification, and the influence of modified bentonite on the soil adsorption and desorption of Pb/Cd was investigated. The potential application of modified bentonite in mitigating the phytotoxicity of Pb/Cd was evaluated by conducting pot experiments, and the environmental risk was evaluated by acid rain leaching test.

Results

Results indicate that the removal rates of Pb/Cd of BTS obtained by 450℃ calcination and 20% citric acid activation reached 88.03% and 80.04%, respectively. Pb/Cd was primarily adsorbed by BTS through coordination between the groups (e.g., siloxane, hydroxyl, and carboxyl) and Pb/Cd. BTS amendment at an appropriate concentration (1%, 3%, and 5%, w/w) to soils contaminated with Pb/Cd resulted in a significant increase in ryegrass yield and chlorophyll (P < 0.05), and it enhanced root activity and antioxidant enzyme activity. Furthermore, under the effect of acid rain at pH 5.0, the release concentrations of Pb/Cd were the lowest when BTS-5% was added, and the cumulative release concentrations were 2.079 and 1.506 mg·L−1, respectively. The extractable acid state increased before and after leaching, whereas the residual state decreased.

Conclusion

BTS (3% and 5%) can reduce the environmental risk level from a strong risk to a slight risk. Furthermore, the results of this study can provide theoretical basis for the promotion and application of bentonite in pollution control.