Vanadium (V) pollution in underground water is continuously aggravated by the improper disposal of tailings, and microscale zero-valent iron (mZVI) after sulfidation and stabilization have been considered as a promising strategy to eliminate V(V) pollution. However, the transport and retention of mZVI after sulfidation and stabilization in porous media have not been elucidated, which is of significance to the practical application. Therefore, this study aimed to decipher the migration mechanism of sulfidated and xanthan gum-stabilized mZVI (S-mZVI@XG) and evaluated its remediation performance for V(V). The introduction of XG substantially enhanced the stability of S-mZVI due to the formation of viscous polymer matrix via steric resistance and electrostatic repulsion. In contrast to the 79.3 % settling of S-mZVI at 10 min, the settling of S-mZVI@XG was only 12 % at 2 h. The transport of S-mZVI@XG was strongly affected by the grain size of porous media, flow rate of underground water, and ironic strength. S-mZVI@XG exhibited a 65.58 % effluent rate with a maximum transport distance of 447.9 cm in coarse sand and under flow rate of 10 m·d-1 and ionic strength of 10 mM. The retention mechanism of S-mZVI@XG in saturated porous media was mainly attributed to the interception. Besides, S-mZVI@XG possessed a greater performance for remediation of V(V) than S-mZVI, particularly for actual underground water. The findings could provide theoretical and technical insights into the practical application of mZVI materials for in situ remediation of V(V) pollution.

中文翻译：

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破译稳定硫化微量零价铁的运输、保留和机理，用于钒 （V） 的原位修复


尾矿处置不当不断加剧地下水中的钒 （V） 污染，硫化稳定后的微量零价铁 （mZVI） 被认为是消除 V（V） 污染的一种有前途的策略。然而，mZVI 在多孔介质中硫化和稳定后的传输和保留尚未阐明，这对实际应用具有重要意义。因此，本研究旨在破译硫化和黄原胶稳定的 mZVI （S-mZVI@XG） 的迁移机制，并评价其对 V（V） 的修复性能。XG 的引入大大提高了 S-mZVI 的稳定性，因为通过空间阻力和静电排斥形成粘性聚合物基质。与 S-mZVI 在 10 分钟时 79.3% 的沉降相比，S-mZVI@XG 在 2 小时时的沉降仅为 12%。S-mZVI@XG 的输运受多孔介质晶粒尺寸、地下水流速和抗腐蚀强度的强烈影响。S-mZVI@XG 在粗砂中流速为 65.58 %，最大传输距离为 447.9 cm，流速为 10 m·d-1，离子强度为 10 mM。S-mZVI@XG 在饱和多孔介质中的保留机制主要归因于截留。此外，S-mZVI@XG 对 V（V） 的修复性能优于 S-mZVI，尤其是对于实际地下水。研究结果可为 mZVI 材料在 V（V） 污染原位修复中的实际应用提供理论和技术见解。