Polyamide reinforced alginate-based hydrogel for efficient uranium extraction from seawater

The sustainable development of nuclear power hinges on accessing sufficient and stable uranium resources. Although the ocean contains abundant uranium, its low concentration and the presence of various interfering ions pose great challenges to extracting uranium from seawater. Herein, the sodium alginate-polyamidoxime/hyperbranched polyamide hydrogel spheres with high stability and adsorption capacity were developed. The gel spheres are molded by crosslinking sodium alginate with Ca²⁺ and form a three-dimensional network structure through the covalent cross-linking of glutaraldehyde, which endows the hydrogel spheres with great stability and forms a pore structure. Accordingly, the unique spherical structure endows it with unparalleled recovery performance, enhancing its ability to efficiently recycle after uranium extraction. Adsorption experiments show that the maximum capacity reaches 537.8 mg·g⁻¹ at a pH of 6. Notably, the hydrogel spheres can adsorb uranium over a larger pH range and maintain morphological stability, which makes them suitable for uranium recovery in complex situations like seawater. Furthermore, the adsorption capacity was successfully preserved in five adsorption–desorption cycles, with a high removal rate from 95.07 % to 87.37 %. The dynamic cycle experiment reveals that uranium extraction in real seawater can still reach 82.59 %, indicating a high potential for seawater applications.