Introducing self-assembly effect in adsorption process for efficient uranium extraction by zwitterion highly-functionalized fibers

Polymeric adsorbents play a crucial role in the extraction of uranium from seawater and nuclear wastewater for the removal and recovery of uranium. However, traditional polymeric uranium adsorbents rely on the coordination between uranyl and ligands, and the uranyl/ligand stoichiometric ratio is generally ≤ 1:1, further limiting their adsorption performances. Herein, phosphorylcholine (PC), a phosphate-containing zwitterionic group, is highly-functionalized on fibers to construct a novel uranium adsorbent denoted by PAN-PC. Interestingly, PAN-PC performs an unprecedented self-assembly effect toward uranyl in the adsorption process. Further investigation reveals that three factors, i) the strong coordination and electrostatic interactions, ii) the zwitterionic nature of PC, and iii) the existence of abundant PC, induce the self-assembly of uranyl on PAN-PC as reverse micelle-like structures. Moreover, the excellent mass transfer performance of PAN-PC contributes to the sufficient utilization of ligands. Consequently, PAN-PC exhibits an ultrahigh stoichiometric ratio > 5:1 and a remarkable adsorption capacity of 2658 mg g−1, which significantly exceeds all reported polymeric uranium adsorbents. Furthermore, the practicality of PAN-PC is also verified in seawater and simulated nuclear wastewater. This is the first adsorbent that introduces the self-assembly effect for significantly enhancing the adsorption performance. This work provides a novel strategy to develop efficient adsorbents for metal ions.