Sulfidated nanoscale zero valent iron for in situ immobilization of hexavalent chromium in soil and response of indigenous microbes

• Published in: Chemosphere (Oxford) 2023-12, Vol.344, p.140343-140343, Article 140343
• Main Authors: Liu, Nuo, Zhang, Yufei, Zheng, Chunli, Tang, Chenliu, Guan, Jie, Guo, Yaoguang
• Format: Article
• Language: English
• Subjects: Hexavalent chromium; Microbes; nZVI; S-nZVI; Soil remediation
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.140343

This study aimed to investigate the immobilization efficiency of sulfidated nanoscale zero valent iron on Cr(VI) in soil. Reactions between sulfidated nanoscale zero valent iron and Cr(VI) in soil system and effects of sulfidated nanoscale zero valent iron on microbes had been demonstrated. Solid characterization results confirmed the incorporation of sulfur into nanoscale zero valent iron. Furthermore, the main oxidation products of iron after the reactions were magnetite, goethite and lepidocrocite. Fe–Cr complexes indicated that Cr(VI) was reduced to Cr(III). The results of 16 S rRNA gene analysis indicated that the sulfidated nanoscale zero valent iron had a limited bactericidal effect but further stimulated the sulfite reductase gene population, representing its positive effect for the soil remediation. The study showed that some microflora such as Protobacteria were promoted, while others community such as Firmicutes, were depressed. Furthermore, Cr mainly converted from a high toxic state such as exchangeable (EX) to less bioavailable state such as iron-manganese oxides bound (OX) and organic matter-bound (OM), thus reducing the toxicity of Cr when sulfidated nanoscale zero valent iron was added. High immobilization efficiency of the Cr(VI) compared to nanoscale zero valent iron indicated an improvement on selectivity and reactivity after sulfidation. Overall, sulfidated nanoscale zero valent iron was promising for the immobilization of Cr(VI) immobilization soil. [Display omitted] •S-nZVI was utilized for efficient remediation of Cr(VI)-contaminated soil.•Cr(VI) removal mechanisms using S-nZVI were studied.•Corrections between indigenous microbes and S-nZVI were elucidated.•Dual effects of S-nZVI on indigenous microbes were proven.