Triple enhancement of uranium extraction from seawater by zwitterions: structural construction, marine adaptability, and synergetic coordination

Seawater uranium extraction via adsorption technology can effectively alleviate the shortage of terrestrial uranium resources and ensure a steady, sustainable supply of essential uranium. Most uranium adsorbents face challenges like inefficient ion transport, salt shrinkage and marine biofouling. Thus, we innovatively constructed zwitterionic marine-adaptive porous cryogel adsorbents (PAO-SBMA) for uranium extraction from seawater. The incorporation of zwitterionic sulfobetaine methacrylate (SBMA) not only regulates the hierarchical pore architecture of porous adsorbents but also imparts superhydrophilicity, antifouling capability, and salt-shrinkage resistance. Additionally, density functional theory (DFT) calculations, FT-IR and XPS spectra jointly prove that the sulfonic acid groups perform as effective synergistic coordinating groups, and facilitate the efficient adsorption of uranium by amidoxime-based adsorbents. Through this “triple enhancement” strategy, the PAO-SBMA-1.5 (m AN /m SBMA  = 1.5) exhibits remarkable uranium adsorption performance. Its adsorption capacity is approximately three times that of the polyamidoxime (PAO), reaching 1595.90 mg/g. After 21 days of test in natural seawater, PAO-SBMA-1.5 demonstrates a high uranium extraction capacity of 13.88 mg/g, and its extraction efficiency has reached as high as 84 %. The zwitterion-based adsorbent is poised to become a promising candidate for implementation in marine uranium extraction operations.