硅胶吸附处理含高浓度硝酸根的含铀工艺废液

Treatment of Uranium-containing Process Wastewater With High Concentration Nitrate by Silica Gel Adsorption Method

  • 摘要: 利用硅胶对铀的吸附作用,实现了对同时含高浓度硝酸根及微量铀的放射性废液中铀的回收。利用模拟废液进行静态实验,研究了溶液pH值、铀初始浓度、硝酸盐浓度及硅胶比表面积对吸附效果的影响。结果表明:溶液pH值增大有利于硅胶对铀的吸附;而溶液中铀初始浓度的升高会使铀在硅胶上的吸附效率降低;pH值为8.1时的吸附过程符合Freundlich等温吸附模型;硝酸根在硅胶上不吸附,且对铀的吸附几乎无影响;具有较大比表面积的硅胶有利于铀的吸附。利用实际工艺废液进行的动态柱实验结果表明,当pH值为8.1时,硅胶对铀的吸附容量可达22.3 mg/g。吸附在硅胶上的铀可被1 mol/L的硝酸溶液淋洗下来,解吸效率达近100%。

     

    Abstract: The silica gel was used to recover uranium from wastewater with high-concentration nitrate ion and trace uranium by uranium adsorption on the silica gel. The adsorption of U(Ⅵ) was investigated under different pH values, initial U(Ⅵ) and nitrate ion concentrations, and specific surface areas of silica gel. The results show that the adsorption is improved as pH increases, and nitrate ion almost has no effect on uranium adsorption, and it is not adsorbed on silica gel. The Freundlich isothermal adsorption model can well represent the adsorption of uranium on silica gel. The silica gel with larger specific surface area is advantageous for uranium adsorption. The adsorption capacity as large as 22.3 mg/g at pH 8.1 is obtained by silica gel column using uranium-containing process wastewater. Besides, it is found that the adadsorbed U(Ⅵ) ions can be almost completely eluted by 1 mol/L nitric acid solution from the column.

     

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