Efficient extraction of U(VI) from uranium enrichment process wastewater by amine-aminophosphonate-modified polyacrylonitrile fibers

The enrichment and recovery of U(VI) from low-level radioactive wastewater in the process of uranium enrichment is important for the sustainable development of nuclear energy and environmental protection. Herein, a novel amine-aminophosphonate bifunctionalized polyacrylonitrile fiber (AAP-PAN), was prepared for the extraction of U(VI) from simulated and real uranium-containing process wastewater. The AAP-PAN fiber demonstrated a maximum adsorption capacity of 313.6 mg g−1 at pH = 6.0 and 318 K in the batch experiments. During the dynamic column experiment, over 99.99% removal of U(VI) could be achieved by the fiber using multi-ion simulated solution and real wastewater with an excellent saturation adsorption capacity of 132.0 mg g−1 and 72.5 mg g−1, respectively. It also exhibited an outstanding reusability for at least 5 cycles of adsorption process. The mechanism for U(VI) removal was studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis in the assist of simulation calculation. It suggested that the amine and aminophosphonate groups can easily bind uranyl ions due to U(VI) is more likely to combine with oxygen atoms of CO and PO, respectively. [Display omitted] •An amino/phosphorylated PAN fiber is successfully synthesized by a three-step hydrothermal method.•The maximum adsorption capacity of AAP-PAN for U (VI) reaches 313.6 mg/g at pH 6 and which has excellent adsorption performance in a wide pH range (6-10).•AAP-PAN can be continuously treated complex uranium wastewater with the effluent U(VI) concentration of 5 μg L-1 to meet national standards for direct discharge.•U(VI) is more likely to bound with oxygen atoms of C=O and P=O on AAP-PAN suggested by the spectral analysis and simulation calculation.