Key Discipline Laboratory for National Defense of Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, 421001, China.
School of Resource Environment and Safety Engineering, University of South China, Hengyang, 421001, China.
Environ Sci Pollut Res Int. 2020 Feb;27(5):5584-5594. doi: 10.1007/s11356-019-07306-0. Epub 2019 Dec 18.
Zero-valent iron (ZVI) has been widely applied to the remediation of uranium (U)-contaminated water. Notably, indigenous bacteria may possess potential positive or unfavorable influence on the mechanism and stability of Fe-U precipitates. However, the focus of the researches in this field has mainly been on physical and/or chemical aspects. In this study, batch experiments were conducted to explore the effects of an indigenous bacterium (Leifsonia sp.) on Fe-U precipitates and the corresponding removal efficiency by ZVI under different environmental factors. The results showed that the removal rate and capacity of U(VI) was significantly inhibited and decreased by ZVI when the pH increased to near-neutral level (pH = 68). However, in the ZVI + Leifsonia sp. coexistence system, the U(VI) removal efficiency were maintained at high levels (over 90%) within the experimental scope (pH = 38). This revealed that Leifsonia sp. had a synergistic effect on U(VI) remove by ZVI. According to scanning electron microscope and energy dispersive X-ray detector (SEM-EDX) analysis, dense scaly uranium-phosphate precipitation was observed on ZVI + Leifsonia sp. surface. The X-photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis indicated that Leifsonia sp. facilitated the generation of U(VI)-phosphates precipitates. The X-ray diffraction (XRD) analyses further revealed that new substances, such as (Fe(II)Fe(III)(PO)(OH)), Fe(II)(UO)(PO)·8HO, Fe(II)Fe(III)(PO)(OH)·4HO, etc., were produced in the coexisting system of ZVI and Leifsonia sp. This study provides new insights on the feasibility and validity of site application of ZVI to U(VI)-contaminated subsurface water in situ. Graphical abstract.
零价铁 (ZVI) 已被广泛应用于受铀 (U) 污染水的修复。值得注意的是，土著细菌可能对 Fe-U 沉淀物的机制和稳定性产生潜在的积极或不利影响。然而，该领域的研究重点主要集中在物理和/或化学方面。在这项研究中，进行了批量实验，以探索土著细菌（菜氏利斯顿氏菌）对不同环境因素下 ZVI 中 Fe-U 沉淀物的影响及其相应的去除效率。结果表明，当 pH 值升高至近中性水平（pH = 68）时，ZVI 显著抑制并降低了 U(VI) 的去除率和容量。然而，在 ZVI + 菜氏利斯顿氏菌共存系统中，U(VI) 的去除效率在实验范围内（pH = 38）保持在较高水平（超过 90%）。这表明菜氏利斯顿氏菌对 ZVI 去除 U(VI) 具有协同作用。根据扫描电子显微镜和能量色散 X 射线探测器 (SEM-EDX) 分析，在 ZVI + 菜氏利斯顿氏菌表面观察到致密的鳞片状铀磷酸盐沉淀。X 光电子能谱 (XPS) 和傅里叶变换红外光谱 (FTIR) 分析表明，菜氏利斯顿氏菌促进了 U(VI)-磷酸盐沉淀物的生成。X 射线衍射 (XRD) 分析进一步表明，在 ZVI 和菜氏利斯顿氏菌共存系统中产生了新的物质，如 (Fe(II)Fe(III)(PO)(OH))、Fe(II)(UO)(PO)·8HO、Fe(II)Fe(III)(PO)(OH)·4HO 等。本研究为 ZVI 在原位受 U(VI) 污染地下水的现场应用的可行性和有效性提供了新的见解。
