Nanocellulose aerogel for highly efficient adsorption of uranium (VI) from aqueous solution.

Cellulose nanofibers (CNFs) aerogel was prepared via simple covalent crosslinking and freeze-drying method. The porous cellulose aerogel possessed high specific surface area and high metal-chelating capacity, which showed fast adsorption kinetics and high adsorption capacity (440.60 mg g-1) in static uranium adsorption process. In the dynamic filtration system, the maximum adsorption capacity reached 194 mg g-1 with the initial concentration of 10 mg L-1. In addition, the CNFs aerogel possessed excellent selectivity and good regeneration ability for uranium adsorption. The integrated analyses of attenuated total reflection Fourier transform infrared (ATR-FTIR), X-Ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) suggested that the predominant UO22+ species formed inner-sphere surface complexes with two active carboxyl groups in the coordination model. This strategy may provide a sustainable route for development of efficient biomass-based adsorbents for selective uranium removal from aqueous solution.