School of Life Science, Shaoxing University, Huancheng West Road 508, Shaoxing 312000, PR China.
State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area, Xi'an University of Technology, Jing Hua Road 5, Xi'an 710048, PR China.
Chemosphere. 2018 Jun;201:764-771. doi: 10.1016/j.chemosphere.2018.03.057. Epub 2018 Mar 10.
Effect of phosphate on the reduction of U(VI) on nZVI was determined by batch, XPS, XANES and EXAFS techniques. The batch experiments showed that nZVI was quite effective for the removal of uranium under the anaerobic conditions, whereas the addition of phosphate enhanced uranium removal over wide pH range. At low pH, the reduction of U(VI) to U(IV) significantly decreased with increasing phosphate concentration by XPS and XANES analysis. According to EXAFS analysis, the occurrence of UU shell at 10 mg/L phosphate and pH 4.0 was similar to that of UO(s), whereas the UP and UFe shells were observed at 50 mg/L phosphate, revealing that reductive co-precipitate (UO(s)) and precipitation of uranyl-phosphate were observed at low and high phosphate, respectively. The findings are crucial for the prediction of the effect of phosphate on the speciation and binding of uranium by nZVI at low pH, which is significant in controlling the mobility of U(VI) in contaminated environments.
采用批实验、XPS、XANES 和 EXAFS 技术研究了磷酸盐对 nZVI 还原 U(VI)的影响。批实验表明，在厌氧条件下，nZVI 对铀的去除非常有效，而磷酸盐的添加可在较宽的 pH 范围内增强铀的去除。在低 pH 条件下，XPS 和 XANES 分析表明，随着磷酸盐浓度的增加，U(VI)向 U(IV)的还原显著降低。根据 EXAFS 分析，在 10 mg/L 磷酸盐和 pH 4.0 时 UU 壳层的出现类似于 UO(s)，而在 50 mg/L 磷酸盐时观察到 UP 和 UFe 壳层，表明在低磷酸盐和高磷酸盐条件下分别观察到了还原共沉淀（UO(s)）和铀磷酸盐沉淀。这些发现对于预测低 pH 条件下磷酸盐对 nZVI 结合铀形态和结合的影响至关重要，这对于控制污染环境中 U(VI)的迁移性具有重要意义。
