ABSTRACT The effects of the flooding and initial Eh of sediments on the sorption of uranium onto the sediments were analysed by flooding and static experiments. The changes in uranium species with Eh and kinetic and thermodynamic characteristics of the uranium sorption onto the sediments were investigated. The flooding experiment indicates that the initial Eh of the sediment gradually decreased with the increase in flooding time. Based on the redox potential in the flooding experiment, simulation results obtained using the geochemical simulation software PHREEQC show that the concentration of U (VI) decreased. In contrast, the concentrations of U (III), U (IV), and U (V) gradually increased. The pseudo-second-order kinetic model well fitted the experimental data, which shows that the sorption was mainly chemical sorption. The thermodynamic parameters suggest that the entropy and enthalpy under the used conditions were positive and that ΔGθ was negative. A thermodynamic analysis shows that the sorption was endothermic and spontaneous. These results are useful for the understanding of the sorption mechanism and migration of uranium onto the sediment under different initial sediment redox potentials and provide a good theoretical foundation for radioactive pollution remediation.

中文翻译：

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氧化还原电位和铀在沉积物上的吸附：动力学和热力学特性

摘要 通过注水和静力实验，分析了注水和沉积物初始 Eh 对铀吸附在沉积物上的影响。研究了铀物种随 Eh 的变化以及铀吸附到沉积物上的动力学和热力学特性。淹水实验表明，随着淹水时间的增加，沉积物的初始Eh逐渐降低。基于驱替实验中的氧化还原电位，利用地球化学模拟软件PHREEQC得到的模拟结果表明，U(VI)的浓度降低。相比之下，U (III)、U (IV) 和 U (V) 的浓度逐渐增加。拟二级动力学模型与实验数据拟合良好，表明吸附以化学吸附为主。热力学参数表明所用条件下的熵和焓为正，ΔGθ 为负。热力学分析表明吸附是吸热和自发的。这些结果有助于理解不同初始沉积物氧化还原电位下铀对沉积物的吸附机理和迁移，为放射性污染修复提供良好的理论基础。