An Ion‐Crosslinked Supramolecular Hydrogel for Ultrahigh and Fast Uranium Recovery from Seawater

Abstract Large‐scale uranium extraction from seawater is a crucial but challenging part of nuclear power generation. In this study, a new ion‐crosslinked supramolecular Zn 2+ –poly(amidoxime) (PAO) hydrogel that can super‐efficiently adsorb uranium from seawater is explored. By simply mixing two solutions of zinc chloride and PAO, a supramolecular Zn 2+ –PAO hydrogel is achieved via the interaction between zinc cations and amidoxime anions. In contrast with existing amidoxime‐functionalized hydrogel‐based adsorbents having low PAO contents and fiber‐based adsorbents with weak hydrophilicity, the PAOs can be directly crosslinked using a small quantity of superhydrophilic zinc ion. Thus, a supramolecular hydrogel is formed, having both a high content of well‐dispersed PAOs and good hydrophilicity. Relative to reported adsorbents, this low‐cost hydrogel membrane exhibits outstanding uranium adsorption performance, reaching 1188 mg g -1 of M U / M dry gel in 32 ppm uranium‐spiked water. More importantly, after immersion in natural seawater for only 4 weeks, the uranium extraction capacity of the Zn 2+ –PAO hydrogel membrane reaches 9.23 mg g -1 of M U / M dry gel . This work can provide a general strategy for designing a new type of supramolecular hydrogel, crosslinked by various bivalent/multivalent cation‐crosslinkers and even many other superhydrophilic supramolecular crosslinkers, for the high‐efficient and massive extraction of uranium from seawater.