阿拉尔河下游沉积物对铀的吸附及其影响因素

Adsorption of Uranium on River Sediments From the Lower Alar River in Qaidam Basin and Its Influencing Factors

采用静态吸附实验,研究了阿拉尔河下游沉积物对水溶液中铀的吸附机制,分析了反应时间、pH值、粒径、固液比、铀初始浓度等因素对沉积物吸附铀的影响,并对其吸附动力学过程和热力学性质进行了探究。结果表明:阿拉尔河河流沉积物对铀的吸附在16 h左右趋于平衡;溶液pH值对沉积物吸附铀具有显著影响,当pH=6~7时,吸附率最大;在一定条件下,吸附率与固液比呈正相关,与粒径及铀初始浓度呈负相关;吸附量与固液比呈负相关,与铀初始浓度呈正相关;吸附动力学过程遵循准二级动力学模型,由两个以上步骤共同控制;吸附热力学符合Freundlich吸附等温模型,沉积物对铀的吸附以多分子层吸附为主,是自发、吸热的熵增过程。

The adsorption mechanism of uranium on sediments from the lower Alar River was investigated by the static experiments. The influence of reaction time, pH, sediments grain sizes, solid-liquid ratio, initial uranium concentration was studied. The results showed that it took about 16 hours to achieve the equilibrium. The adsorption of uranium on sediments was strongly dependent on pH, and the adsorption rate reached the highest when the pH value was between 6 and 7. Under certain conditions, the adsorption rate of uranium on sediments was positively correlated with the solid -liquid ratio, and negatively correlated with the sediments grain sizes and the initial uranium concentration. But the adsorption capacity was negatively correlated with the solid-liquid ratio, and positively correlated with the initial uranium concentration. The adsorption kinetics conformed to the pseudo second order kinetic model, and the whole process was under the control of more than two steps. The adsorption isotherm was consistent with the Freundlich isothermal absorption model, and the adsorption of uranium on sediments was multilayer adsorption. The adsorption was an endothermic and spontaneous entropy increase process.