Fabrication of amidoxime functionalized hyper-cross-linked polymer for efficient extraction of uranium (VI) from water

Abstract

Pollution, such as uranium(U), resulting from radionuclides, has become a severe environmental problem. Hence, developing highly efficient materials to reduce the environmental influence of uranium is necessary. Here, amidoxime functionalized hyper-cross-linked fluorene-9-bisphenol (HCP-AO) was synthesized by a Friedel–Crafts reaction followed by an amidoxime functionalization as a novel uranium adsorbent. The sorption properties of HCP-AO for U (VI) from water were evaluated in various environmental conditions (e.g., solution pH, contact time, temperature, etc.). The HCP-AO was characterized by a series of characterization methods. The HCP-AO’s maximum U(VI) sorption capacity was 234.46 mg/g (pH = 7) due to the strong coordination of amidoxime groups (AO) with uranium. The sorption data well matched with Langmuir isotherm and the pseudo-second-order kinetic model. Even with competing metal ions, HCP-AO exhibited selective uranium adsorption capacity. After three regeneration cycles, the HCP-AO’s adsorption capacity was still considerable. These findings indicated that HCP-AO could be used to extract uranium from uranium-bearing wastewater.