Natural cellulose-based microspheres decorated with amidoxime groups for decontamination of radioactive wastewater

Abstract

The effective treatment of uranium (U)-containing radioactive wastewater that from the mining process and nuclear leakage accidents is considered as the promise for the sustainable development of nuclear energy. Herein, amidoxime-functionalized microspheres with high grafting densities were prepared by the non-solvent induced phase separation and followed by surface chemical modifications while choosing celluloses as the raw materials in terms of broad resource, good hydrophilicity, and antimicrobial property. The excellent hydrophilicity of cellulose could reduce the rates of phase separation, leading to porous surface structures and spongy internal structures. In addition, the following swelling treatments would further modulate for higher pore sizes and porosities which could not only create more reaction sites during the modification but also promote the mass transfer as well as increase contact areas and retention times during the adsorption process. The obtained microspheres could selectively decontaminate more than 390 mg/g of uranium due to their abundant adsorption sites. In addition, their outstanding hydrophilicity endows them with good reusability and anti-fouling properties. The microspheres could also be put into filtration columns for long-term and dynamic adsorption which could be regarded as a decided advantage compared with common fiber-based adsorbents. The filtration columns could capture more than 17 mg/g after 20 days of uranium even with ultralow initial uranium concentrations and ultrahigh concentrations of other coexisting ions, demonstrating their desirable potentials in remediating radioactive wastewater.