Amidoxime-Functionalized Wood-Based Adsorbent for Uranium Extraction

Uranium is a critical raw material for the nuclear industry. Given the vast uranium reserves in seawater, the development of efficient adsorbents is central to extraction technologies. Polyamidoxime (PAO)-based adsorbents are widely utilized due to their high affinity for uranium; however, traditional PAO materials often suffer from low mechanical strength and poor recyclability. To address these limitations, this study utilized natural balsa wood as a substrate. A three-dimensional porous cellulose skeleton (DES-W) featuring high porosity, hydrophilicity, and retained mechanical strength was constructed by partially removing lignin using a deep eutectic solvent (DES). Subsequently, polyamidoxime was loaded onto the inner walls of the DES-W via vacuum impregnation, resulting in a polyamidoxime-functionalized wood-based adsorbent (PAO-WA). The results indicated that PAO-WA achieved an equilibrium adsorption capacity of 45.31 mg/g at pH 6.0 with an initial uranium concentration of 50 mg/L, representing a twofold increase compared to the unmodified DES-W. The adsorption kinetics and isotherms followed the pseudo-second-order and Langmuir models, respectively, suggesting a mechanism dominated by monolayer chemisorption. Mechanism analysis confirmed that uranyl ions were primarily captured via coordination with nitrogen and oxygen atoms in the amidoxime groups, with residual carboxyl groups in the wood contributing to the adsorption process. This work offers a novel strategy for developing efficient, environmentally friendly, and mechanically robust adsorbents for uranium extraction from seawater.