Horizontally arranged covalent organic framework nanowires on poly(amidoxime) fibers for high-efficiency uranium capture.

The efficient capture of low-concentration uranium (with a concentration range of 10-50 ppm) from nuclear and metallurgical wastewaters is crucial for safeguarding the ecological security of water bodies. Herein, an ion coordination approach was proposed to achieve the controlled arrangement of covalent organic framework (COF) nanowires, with these nanowires being horizontally aligned on the surface of poly(amidoxime) (PAO) fibers. At the interface, the amidoxime groups of PAO and the photocatalytic sites of COF enable synergistic chemical binding and photoreduction of soluble uranium into (UO2)O2·4H2O precipitates. This efficient integration of the two pathways enables an ultrahigh uranium uptake capacity of 1259 mg g-1 within 12 hours (~10 ppm), reducing the extraction time to 1/10 that of the pristine COF nanowires. Notably, in the uranium-spiked metallurgical wastewater with a uranium concentration of ~50 ppm, the COF composite attains a uranium uptake capacity of 9230 mg g-1, establishing a new benchmark for uranium adsorption capacity among existing materials.