Doctoral student Junxiang Wu and colleagues in our team, under the joint supervision of Researcher Liangbin Li and Professor Yanan Ye, focused on key challenges associated with polyamidoxime-based adsorbents for uranium extraction from seawater, including low mass-transfer efficiency and poor uranium/vanadium selectivity. By combining a swelling-restricted pore-locking strategy with regulation of the cyclic imide dioxime content, the team achieved orthogonal control over the physical structure and chemical properties of polyamidoxime and developed macroporous polyamidoxime particles (SPP-PAO) with a tunable proportion of cyclic imide dioxime functional groups. This approach effectively alleviated problems commonly encountered during the modification of conventional polyamidoxime adsorbents, including pore collapse, insufficient uranium/vanadium selectivity, and low mass-transfer efficiency, providing a new materials-design strategy for the scale-up of uranium extraction from seawater. The related work was published in Chemical Engineering Journal.
In this study, the team employed commercial polyacrylonitrile (PAN) as the precursor and prepared SPP-PAO adsorbents through amidoximation in a water–methanol cosolvent system. Methanol was used as a poor solvent to restrict swelling of the polymer chains, thereby preserving the macroporous structure. Meanwhile, precise regulation of the concentrations of open-chain amidoxime (AO) and cyclic imide dioxime (IO) groups was achieved by adjusting the alkali concentration. The study systematically revealed the structure–property relationships between pore structure and adsorption performance, as well as between functional-group composition and uranium selectivity. After five consecutive adsorption–desorption cycles, the adsorption-capacity retention remained at or above 80%. Using 0.5 M hydrochloric acid as the desorption solution, more than 95% elution efficiency was achieved within 10 min. More importantly, the material was successfully scaled up to the kilogram level, with a single batch in a 50 L reactor yielding 4.4 kg of product. Four parallel batches all exhibited adsorption capacities exceeding 300 mg g−1 in a uranium solution with a concentration of 4 mg L−1, while the unit production cost was only 13.55 USD kg−1. Based on these results, the proposed strategy combining swelling-restricted pore locking with orthogonal regulation of cyclized functional groups enables the resulting SPP-PAO adsorbent to simultaneously exhibit a macroporous structure, rapid mass transfer, high uranium/vanadium selectivity, and good cycling stability.
This work establishes an orthogonal regulatory relationship between macroporous structure and the proportion of cyclized functional groups, and systematically investigates the synergistic relationships between pore structure and adsorption kinetics, as well as between functional-group composition and selectivity, in polyamidoxime-based adsorbents. The findings provide experimental evidence and a technical route for the development of scalable, low-cost, and highly selective materials for uranium extraction from seawater.
This work was supported by the National Natural Science Foundation of China (52303028), the Institutionalized Platform Project (JZHKYPT-2021-04), and the Innovation and Development Fund of the China Uranium Extraction from Seawater Technology Innovation Alliance (No. CNNC-HSTY-2024-003 and No. CNNC-CXLM-202207).
Wu, J.; He, Y.; Zhang, X.; Mo, H.; Wang, Y. N.; Chen, S.; Song, Z.; Ye, Y. N.; Li, L. Macroporous polyamidoxime particles with tunable cyclization functionalization via a swelling-restricted pore-locking preservation strategy for efficient uranium extraction from seawater. Chemical Engineering Journal 2026, 542, 178224.
Paper Link: https://doi.org/10.1016/j.cej.2026.178224
