Defect-Induced Method for Preparing Hierarchical Porous Zr–MOF Materials for Ultrafast and Large-Scale Extraction of Uranium from Modified Artificial Seawater

Metal–organic framework materials (MOFs) have attracted the attention of researchers as a new type of adsorbent material with large specific surface area and high adsorption capacity. In order to obtain a larger surface area and more adsorption active sites for MOF, we synthesized a hierarchical porous UIO-66 (HP-UIO-66) MOF material by the defect induction method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to define the efficiency of HP-UIO-66-15 and HP-UIO-66-35 material synthesis. Adsorption experiments were carried out to study the uranium adsorption properties of the adsorbents. The results show that the optimal adsorption pH values of the two adsorbents are alkaline conditions. The adsorption process accords with the Langmuir isotherm model and the pseudo-second-order rate equation. The saturated adsorption capacity can reach 1217 mg/g. Compared with the recent UIO-66 study of uranium adsorption, we not only increased the saturated adsorption capacity of HP-UIO-66 MOF material by more than 20% but also achieved the adsorption equilibrium of HP-UIO-66 material in 2 min, showing the ultrafast extraction ability of uranium. XPS analysis showed that the removal of uranium was mainly related to the Zr–O bond in HP-UIO-66 material, which proved that the Zr–O bond played a big role in the adsorption process.