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Purpose <p>Heavy metal pollution, particularly persistent lead (Pb) contamination in soils, poses severe risks to ecosystem and human health. This study aims to develop a novel magnetic molecular sieve (MMS) from coal fly ash (CFA) for efficient Pb adsorption, stabilization, and magnetic recovery in contaminated soils, addressing both waste valorization and sustainable remediation.</p> Materials and methods <p>MMS was synthesized via hydrothermal method using CFA as the silicon and aluminum source. The material was characterized by XRD, SEM, VSM, and N₂ adsorption/desorption. Batch adsorption experiments were conducted to evaluate Pb adsorption behavior. Pb-contaminated soil was treated with MMS (0.5–5%), followed by BCR sequential extraction and magnetic separation to assess Pb fractionation and removal efficiency.</p> Results and discussion <p>MMS exhibited superparamagnetism, high surface area, and a pore size of 2.1–4.5&#xa0;nm. The Langmuir model best fitted Pb adsorption, with a maximum capacity of 585.4&#xa0;mg/g. In soil, 0.5% MMS converted reducible Pb to oxidizable forms, while ≥ 1% further transformed exchangeable Pb into residual fractions. Magnetic separation achieved 33.2% and 41.5% Pb removal at 1% and 5% MMS doses, respectively. Sequential extraction verified MMS preferentially adsorbed RE and EX fractions, enabling their magnetic extraction from soil.</p> Conclusion <p>MMS effectively stabilizes and magnetically removes Pb from soil, demonstrating high adsorption capacity and structural stability. This strategy transforms hazardous CFA into a functional material for soil remediation, supporting contamination mitigation and resource circularity in catchment management.</p>

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Immobilization and magnetic removal of lead in contaminated soils using a waste-derived magnetic molecular sieve

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • Chang Lei,
  • Xiu-Ru Xie,
  • Lai-Shou Long,
  • Rui Li,
  • Zhi-Ping Fu,
  • Zhi-Yue Zhao

摘要

Purpose

Heavy metal pollution, particularly persistent lead (Pb) contamination in soils, poses severe risks to ecosystem and human health. This study aims to develop a novel magnetic molecular sieve (MMS) from coal fly ash (CFA) for efficient Pb adsorption, stabilization, and magnetic recovery in contaminated soils, addressing both waste valorization and sustainable remediation.

Materials and methods

MMS was synthesized via hydrothermal method using CFA as the silicon and aluminum source. The material was characterized by XRD, SEM, VSM, and N₂ adsorption/desorption. Batch adsorption experiments were conducted to evaluate Pb adsorption behavior. Pb-contaminated soil was treated with MMS (0.5–5%), followed by BCR sequential extraction and magnetic separation to assess Pb fractionation and removal efficiency.

Results and discussion

MMS exhibited superparamagnetism, high surface area, and a pore size of 2.1–4.5 nm. The Langmuir model best fitted Pb adsorption, with a maximum capacity of 585.4 mg/g. In soil, 0.5% MMS converted reducible Pb to oxidizable forms, while ≥ 1% further transformed exchangeable Pb into residual fractions. Magnetic separation achieved 33.2% and 41.5% Pb removal at 1% and 5% MMS doses, respectively. Sequential extraction verified MMS preferentially adsorbed RE and EX fractions, enabling their magnetic extraction from soil.

Conclusion

MMS effectively stabilizes and magnetically removes Pb from soil, demonstrating high adsorption capacity and structural stability. This strategy transforms hazardous CFA into a functional material for soil remediation, supporting contamination mitigation and resource circularity in catchment management.