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Purpose <p>The lead (Pb) pollution in agricultural soils poses a significant threat to crop growth and human health, therefore, it is urgent to remediate lead-contaminated soil. In this study, the thermally activated Mg-Al hydrotalcite prepared by simply calcining the original Mg-Al hydrotalcite at various temperatures (200, 400, 600, and 800&#xa0;°C) was employed to immobilize Pb in soil. The influence of calcination temperature of Mg-Al hydrotalcite on Pb immobilization efficiency was investigated.</p> Methods <p>The immobilization effect of Pb by natural and thermally activated Mg-Al hydrotalcite was comprehensively examined through soil incubation experiments. In addition, DFT calculation and XRD, XPS, FTIR characterizations further revealed the immobilization mechanism of materials.</p> Results <p>The addition of thermally activated Mg-Al hydrotalcite significantly reduced the content of TCLP-Pb (toxicity characteristic leaching procedure-Pb) in soil, primarily through its induction of soil pH increase. Moreover, the transformation of Pb from the acid-soluble form to the residual form in soil could be promoted by adding thermally activated Mg-Al hydrotalcite, thereby reducing its bioavailability. Adding 3% CHT600 (Mg-Al hydrotalcite activated at 600&#xa0;°C) into the soil with 150 days of incubation exhibited better performance to immobilization of Pb, and it could reduce the acid-soluble Pb fractions by 29% and increase the residual Pb 40% relative to the control group, respectively. By virtue of XRD, XPS, and DFT calculation, it would be inferred that the bioavailable form of Pb could be effectively reduced by thermally activated Mg-Al hydrotalcite through electrostatic attraction, physical adsorption, precipitation, complexation, and so on.</p> Conclusion <p>An efficient thermally activated Mg-Al hydrotalcite for Pb immobilization in soil was obtained by optimizing the calcination temperature. Meanwhile, the increase of soil pH value, thermally activated Mg-Al hydrotalcite application amount, incubation time, and material properties would play an important role in immobilization heavy metal. This result provided a new insight into developing cost-effective, environmentally friendly Mg-Al hydrotalcite for scalable remediation of Pb-contaminated soils.</p>

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Remediation of Pb-contaminated soils using thermally activated Mg-Al hydrotalcite

  • 期刊论文

  • 发表日期：

    2025年4月21日

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  • Chun-Yan Cao,
  • Wen-Ling Long,
  • Si-Lin Chen,
  • Ming-Hui Nie,
  • Min Wang,
  • Shuang Zhao,
  • Xin Wan

摘要

Purpose

The lead (Pb) pollution in agricultural soils poses a significant threat to crop growth and human health, therefore, it is urgent to remediate lead-contaminated soil. In this study, the thermally activated Mg-Al hydrotalcite prepared by simply calcining the original Mg-Al hydrotalcite at various temperatures (200, 400, 600, and 800 °C) was employed to immobilize Pb in soil. The influence of calcination temperature of Mg-Al hydrotalcite on Pb immobilization efficiency was investigated.

Methods

The immobilization effect of Pb by natural and thermally activated Mg-Al hydrotalcite was comprehensively examined through soil incubation experiments. In addition, DFT calculation and XRD, XPS, FTIR characterizations further revealed the immobilization mechanism of materials.

Results

The addition of thermally activated Mg-Al hydrotalcite significantly reduced the content of TCLP-Pb (toxicity characteristic leaching procedure-Pb) in soil, primarily through its induction of soil pH increase. Moreover, the transformation of Pb from the acid-soluble form to the residual form in soil could be promoted by adding thermally activated Mg-Al hydrotalcite, thereby reducing its bioavailability. Adding 3% CHT600 (Mg-Al hydrotalcite activated at 600 °C) into the soil with 150 days of incubation exhibited better performance to immobilization of Pb, and it could reduce the acid-soluble Pb fractions by 29% and increase the residual Pb 40% relative to the control group, respectively. By virtue of XRD, XPS, and DFT calculation, it would be inferred that the bioavailable form of Pb could be effectively reduced by thermally activated Mg-Al hydrotalcite through electrostatic attraction, physical adsorption, precipitation, complexation, and so on.

Conclusion

An efficient thermally activated Mg-Al hydrotalcite for Pb immobilization in soil was obtained by optimizing the calcination temperature. Meanwhile, the increase of soil pH value, thermally activated Mg-Al hydrotalcite application amount, incubation time, and material properties would play an important role in immobilization heavy metal. This result provided a new insight into developing cost-effective, environmentally friendly Mg-Al hydrotalcite for scalable remediation of Pb-contaminated soils.