ZIF-8-SiO₂ and adsorption on U(VI)

Zeolite imidazole ester framework structure material ZIF-8 and TEOS were used to prepare ZIF-8-SiO₂ composite, the structure of ZIF-8-SiO₂ and the morphology before and after adsorption of U(VI) were characterized by XRD, SEM, EDS. And the results show that ZIF-8-SiO₂ is successfully prepared and has a good adsorption effect on U(VI). The effects of pH value, time, temperature, initial uranium concentration and salt concentration on the adsorption performance of ZIF-8-SiO₂ were investigated by static adsorption experiments. According to the experimental results, when the initial concentration is 80 mg·g⁻¹, the maximum actual adsorption capacity of ZIF-8-SiO₂ on U(VI) at 25℃ is 498 mg·g⁻¹, and according to the analysis of Langmuir model fitting results, the theoretical adsorption capacity of the material on U(VI) is up to 678.5 mg·g⁻¹. And in the range of 200~500 MPa, the higher the pressure, the better the adsorption. FTIR and XPS were used to characterize the structure of the material before and after uranylion adsorption, to explore the possible adsorption mechanism during the adsorption process.