Dual-functional synergistic modification of cellulose with phosphate and amidoxime for high-efficiency uranium capture in acidic wastewater.

The selective separation of uranium from acidic radioactive wastewater is critical for mitigating environmental hazards and safeguarding public health. Cellulose-based adsorbents have the advantages of abundant resources, low cost and degradability, but there is a problem of low adsorption efficiency for uranium under acidic conditions. Here, we present a cellulose-based adsorbent with engineered phosphate-amidoxime dual functionalities (PAFC) that overcomes the problem through molecular-scale coordination design. Leveraging the complementary binding affinities of phosphate and amidoxime groups, PAFC achieves exceptional uranium adsorption performance across broad pH adaptability (3-9), exhibiting >96% removal efficiency at 100 mg·L-1 uranium within 60 min. The material maintains 76% removal efficiency after ten regeneration cycles. X-ray photoelectron spectroscopy analyses and density functional theory calculations reveal that phosphate groups effectively suppress the protonation of amidoxime groups under acidic conditions, and their synergistic interaction significantly enhances the UO22+ adsorption binding energy compared to systems containing only a single functional group. This study provides a general paradigm for developing cellulose-based adsorbents through rational dual-functional modification with phosphate and amidoxime groups, addressing the critical need for sustainable nuclear wastewater remediation technologies.