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Purpose <p>This study developed a lanthanum-modified red clay (LaRC) to inhibit tungsten (W) release from contaminated lake sediments, and investigated its immobilization efficiency and underlying mechanisms compared to unmodified red clay (RC).</p> Materials and methods <p>LaRC was synthesized via a liquid-phase method. Batch adsorption isotherms were fitted using Langmuir, Freundlich, and D-R models. Sediment cores from Yangcheng Lake were capped with RC or LaRC in a controlled incubation experiment. Dissolved oxygen (DO) and pH were measured by microelectrodes; soluble W, Fe(II), and Mn in porewater were analyzed using HR-Peeper and ICP-MS. X-ray photoelectron spectroscopy (XPS) and sequential extraction were employed to characterize geochemical fractions and binding mechanisms.</p> Results and discussion <p>LaRC exhibited a higher maximum W adsorption capacity (83.94&#xa0;mg g⁻<sup>1</sup>) than RC (54.73&#xa0;mg g⁻<sup>1</sup>). LaRC capping reduced soluble W concentrations in porewater by 56.1% and diffusive flux by 0.98&#xa0;µg m⁻<sup>2</sup> d⁻<sup>1</sup>, outperforming RC. XPS and D-R model analyses revealed that LaRC immobilizes W via formation of stable La–W precipitates (like La<sub>2</sub>(WO<sub>4</sub>)<sub>3</sub>), whereas RC relies on adsorption onto Fe(III)/Mn(IV) hydroxides. The La–W precipitates remained stable even under reducing conditions, as evidenced by decoupled trends of rising soluble Fe(II)/Mn and declining W under LaRC treatment.</p> Conclusions <p>LaRC capping effectively suppresses sedimentary W release by converting labile W into stable La–W precipitates. With higher adsorption capacity and better remediation performance than existing materials, LaRC offers a promising approach for managing W contamination in aquatic sediments.</p>

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Efficiency and mechanism of lanthanum-modified red clay for sequestering tungsten in lake sediments

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Hanxiao Wang,
  • Jiabao Yan,
  • Li Zhou,
  • Dongdong Zhu,
  • Qi Li,
  • Yan Wang,
  • Jing Xiao,
  • Lan Zhang,
  • Xiaohui You,
  • Xiang Chen,
  • Xiaoshuai Hang

摘要

Purpose

This study developed a lanthanum-modified red clay (LaRC) to inhibit tungsten (W) release from contaminated lake sediments, and investigated its immobilization efficiency and underlying mechanisms compared to unmodified red clay (RC).

Materials and methods

LaRC was synthesized via a liquid-phase method. Batch adsorption isotherms were fitted using Langmuir, Freundlich, and D-R models. Sediment cores from Yangcheng Lake were capped with RC or LaRC in a controlled incubation experiment. Dissolved oxygen (DO) and pH were measured by microelectrodes; soluble W, Fe(II), and Mn in porewater were analyzed using HR-Peeper and ICP-MS. X-ray photoelectron spectroscopy (XPS) and sequential extraction were employed to characterize geochemical fractions and binding mechanisms.

Results and discussion

LaRC exhibited a higher maximum W adsorption capacity (83.94 mg g⁻1) than RC (54.73 mg g⁻1). LaRC capping reduced soluble W concentrations in porewater by 56.1% and diffusive flux by 0.98 µg m⁻2 d⁻1, outperforming RC. XPS and D-R model analyses revealed that LaRC immobilizes W via formation of stable La–W precipitates (like La2(WO4)3), whereas RC relies on adsorption onto Fe(III)/Mn(IV) hydroxides. The La–W precipitates remained stable even under reducing conditions, as evidenced by decoupled trends of rising soluble Fe(II)/Mn and declining W under LaRC treatment.

Conclusions

LaRC capping effectively suppresses sedimentary W release by converting labile W into stable La–W precipitates. With higher adsorption capacity and better remediation performance than existing materials, LaRC offers a promising approach for managing W contamination in aquatic sediments.