Efficient removal of U(VI) from wastewater by a sponge-like 3D porous architecture with hybrid electrospun nanofibers

Removal of uranium(VI) from nuclear wastewater is urgent due to the global nuclear energy exploitation. This study synthesized novel sponge-like 3D porous materials for enhanced uranium adsorption by combining electrospinning and fibrous freeze-shaping techniques. The materials possessed an organic–inorganic hybrid architecture based on the electrospun fibers of polyacrylonitrile (PAN) and SiO₂. As a supporting material, the surface of fibrous SiO₂ could be further functionalized by cyano groups via (3-cyanopropyl)triethoxysilane. All the cyano groups were turned into amidoxime (AO) groups to obtain a amidoxime-functionalized sponge (PAO/SiO₂-AO) through the subsequent amidoximation process. The proposed sponge exhibited enhanced uranium adsorption performance with a high removal capacity of 367.12 mg/g, a large adsorption coefficient of 4.0 × 10⁴ mL/g, and a high removal efficiency of 97.59%. The ${\text{UO}}_2^{2+}$ adsorption kinetics perfectly conformed to the pseudo-second-order reaction. The sorbent also exhibited an excellent selectivity for ${\text{UO}}_2^{2+}$ with other interfering metal ions.