ZIF-8 in-situ growth on amidoximerized polyacrylonitrile beads for uranium sequestration in wastewater and seawater

With the vigorous development of nuclear power and the shortage of terrestrial uranium resources, the extraction uranium from seawater is extremely attractive for human development. Herein, we first report ZIF-8 in-situ growth on amidoximerized polyacrylonitrile (PAO) porous materials. The porous material is a small sphere with certain mechanical strength synthesized by solvent-induced phase separation method. Because ZIF-8 nanocrystals are well-formed and evenly distributed within the PAO beads, ZIF-8/PAO has a high specific surface area (386 m2 g-1) and rich pore structure. At adsorption experiment, the highest adsorption capacity of ZIF-8/PAO reached 803 mg g-1 at pH = 4. Furthermore, competitive adsorption experiment and simulated seawater test was studied. The selectivity for uranium was excellent (Kd = 1.7 × 105 mL g-1) and uranium adsorption rate reached 99% at 3 ug L-1. XPS analysis shows that U(VI) is chelated by imidazole-N atoms and amidoxime groups in ZIF-8/PAO. Therefore, ZIF-8/PAO can be considered a highly promising adsorbent for uranium extraction from wastewater and seawater.