Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001, P. R. China.
Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001, P. R. China; Yantai Research Institute, Harbin Engineering University, Yantai 264006, Shandong, P. R. China.
Sci Total Environ. 2022 Aug 25;836:155609. doi: 10.1016/j.scitotenv.2022.155609. Epub 2022 Apr 30.
Electrochemical techniques are considered promising applications to immobilize uranium in alkaline wastewater in order to prevent its migration into groundwater and soil. In this work, the results of electrochemical and Atomic Force Microscope (AFM) demonstrate a successful immobilization of uranyl in the carbonate system by U(VI)-U(V), U(V)-U(IV) reduction, and U(V) disproportionation reactions. The results indicated that the electrochemical fixation rate in alkaline system could reach more than 99%. The valence state of uranium is the key factor affecting its migration in the working system. Where, the analysis of the immobilized samples by X-ray photoelectron spectroscopy (XPS) revealed that pHs, current density, and the presence of foreign cations significantly affect the valence state of uranium in the immobilized samples. Under same conditions, the reduction reactions of U(VI)-U(V) and U(V)-U(IV) occurred easily. Where, at pH higher than 3.4 or the current density in the range of 0.5-20 mA/cm, high content of U(V) and U(IV) in the immobilized products was obtained. Other conditions favored the occurrence of the electrolytic water reaction, and the immobilized samples were dominated by U(VI). It was found that the temperature showed the greatest effect on the electrochemical immobilization rate. Where, the electrochemical immobilization rate increased by about 1.8 times when the ambient temperature increased from 293.15 to 328.15 K. This study provides a new idea for the immobilization of uranium in alkaline wastewater and demonstrates the feasibility of electrochemical immobilization of uranium in alkaline systems.
电化学技术被认为是将铀固定在碱性废水中以防止其迁移到地下水和土壤中的有前途的应用。在这项工作中，电化学和原子力显微镜（AFM）的结果表明，通过 U(VI)-U(V)、U(V)-U(IV)还原和 U(V)歧化反应，成功地将铀酰固定在碳酸盐系统中。结果表明，碱性系统中的电化学固定率可达到 99%以上。铀的价态是影响其在工作系统中迁移的关键因素。其中，X 射线光电子能谱（XPS）分析表明，pH 值、电流密度和外加阳离子的存在显著影响固定样品中铀的价态。在相同条件下，U(VI)-U(V)和 U(V)-U(IV)的还原反应容易发生。其中，在 pH 值高于 3.4 或电流密度在 0.5-20 mA/cm 的范围内，固定产物中获得了高含量的 U(V)和 U(IV)。其他条件有利于水电解反应的发生，固定样品主要由 U(VI)组成。研究发现，温度对电化学固定速率的影响最大。其中，当环境温度从 293.15 升高到 328.15 K 时，电化学固定速率增加了约 1.8 倍。本研究为碱性废水中铀的固定提供了新的思路，并证明了电化学固定碱性系统中铀的可行性。
