Environmental Protection and Safety Engineering, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory of Soil Pollution Control and Remediation, University of South China, Hengyang, 421001, China.
Environmental Protection and Safety Engineering, University of South China, Hengyang, 421001, China.
J Environ Radioact. 2024 Mar;273:107398. doi: 10.1016/j.jenvrad.2024.107398. Epub 2024 Feb 11.
Enzymatically catalyzed reduction of metals by bacteria has potential application value to uranium-mine wastewater. However, its practical implementation has long been restricted by its intrinsic drawbacks such as low efficiency and long treatment-time. This study aims to explore the effect of electrodes on U (VI) removal efficiency by a purified indigenous bacteria isolated from a uranium mining waste pile in China. The effects of current intensity, pH, initial U (Ⅵ) concentration, initial dosage of bacteria and contact time on U (Ⅵ) removal efficiency were investigated via static experiments. The results show that U(VI) removal rate was stabilized above 90% and the contact time sharply shortened within 1 h when utilized nickel-graphite electrode as an electron donor. Over the treatment ranges investigated maximum removal of U (Ⅵ) was 96.04% when the direct current was 10 mA, pH was 5, initial U (Ⅵ) concentration was 10 mg/L, and dosage of Leifsonia sp. was 0.25 g/L. In addition, it is demonstrated that U (VI) adsorption by Leifsonia sp. is mainly chemisorption and/or reduction as the quasi-secondary kinetics is more suitable for fitting the process. FTIR results indicated that amino, amide, aldehyde and phosphate -containing groups played a role in the immobilization of U (VI) more or less. SEM and EDS measurements revealed that U appeared to be more obviously aggregated on the surface of cells. A plausible explanation for this, supported by XPS, is that U (VI) was partially reduced to U (IV) by direct current then precipitated on the cells surface. These observations reveal that Nickel-graphite electrode exhibited good electro-chemical properties and synergistic capacity with Leifsonia sp. which potentially provides a new avenue for uranium enhanced removal/immobilization by indigenous bacteria.
细菌酶促还原金属对铀矿山废水具有潜在的应用价值。然而，其实际应用长期以来一直受到效率低和处理时间长等固有缺陷的限制。本研究旨在探索从中国铀矿堆中分离出的一株土著细菌对电极去除 U（VI）效率的影响。通过静态实验考察了电流强度、pH 值、初始 U（VI）浓度、初始细菌用量和接触时间对 U（VI）去除效率的影响。结果表明，当采用镍石墨电极为电子供体时，U（VI）去除率稳定在 90%以上，接触时间在 1 h 内迅速缩短。在考察的处理范围内，当直流电流为 10 mA、pH 值为 5、初始 U（VI）浓度为 10 mg/L、Leifsonia sp.用量为 0.25 g/L 时，U（VI）的最大去除率为 96.04%。此外，研究表明 Leifsonia sp.对 U（VI）的吸附主要是化学吸附和/或还原，准二级动力学更适合拟合该过程。FTIR 结果表明，含氨基、酰胺基、醛基和磷酸基的基团或多或少地参与了 U（VI）的固定化。SEM 和 EDS 测量结果表明，U 似乎更明显地聚集在细胞表面。XPS 的结果支持了这一观点，即 U（VI）部分被直流还原为 U（IV），然后沉淀在细胞表面。这些观察结果表明，镍石墨电极具有良好的电化学性能和与 Leifsonia sp.的协同能力，这为土著细菌增强铀去除/固定提供了新途径。
