Effects of chain conformation on uranium adsorption performance of amidoxime adsorbents

The amidoxime group has received widespread attention owing to its high affinity for uranium. Since this property was discovered, various amidoxime-based adsorbents have been developed for uranium adsorption. However, the effect of chain conformation on the uranium adsorption performance (in terms of adsorption capacity, stability, selectivity, etc.) of amidoxime adsorbents has rarely been studied. Herein, three amidoxime-based adsorbents with different chain conformations (linear, multi-armed, and rigid) were constructed via tert-butyl hydroperoxide-initiated surface graft polymerization by incorporating different monomer structures. Adsorption experiments revealed that the linear structure of P-E-PAO exhibited the highest adsorption capacity owing to the highest monomer-grafting ratio; the multi-arm structure of P-E-PMGO was affected by pH and ionic strength because of the most cyclic imide dioxime structure; and the rigid structure of P-E-PEBO showed the highest selectivity owing to the most open-chain amidoxime structure. These findings are expected to have strong implications in the optimization of adsorption material designs.