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

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.