Porous and biofouling-resistant amidoxime-based hybrid hydrogel with excellent interfacial compatibility for high-performance recovery of uranium from seawater

For a massive uranium recovery from seawater, designing an adsorbent with ultrahigh uranium uptake capacity and good biofouling-resistant activity is crucial, but difficult. Here, a facile and eco-friendly freeze-thawing strategy was explored for the first time to create a physically crosslinked poly(amidoxime) (PAO)-chitosan (CS) hybrid hydrogel (PAO@CHM) with excellent interfacial compatibility, superior uranium uptake capacity and good anti-biofouling activity. The porous 3D network architecture of PAO@CHM, combined with its good hydrophilicity as well as antibacterial property, synergistically constructs numerous hydrophilic and biofoulingresistant ion channels for the rapid diffusion of uranyl ions into the interior of the hydrogel, achieving maximum use of adsorption active sites on PAO@CHM. Consequently, superior uranium uptake capacities (743.87, 865.27, and 1091.53 mg g(-1) for PAO fixed on hydrogel) were obtained in 8, 16, and 32 ppm U-spiked water, respectively. Benifiting from the enhanced uranium adsorption activity and good antibacterial property, the uranium extraction capacity of PAO@CHM reached 7.46 mg g(-1) after 28 days of exposure in 500 L of natural seawater, which is significantly higher than that of most of adsorbents. The O and N atoms in amidoxime group act as main bonding sites for uranium uptake. The finding of this study provides a facile and eco-friendly strategy to construct hydrophilic and biofouling-resistant amidoxime-based adsorbent for efficient uranium recovery from seawater.

Automated summary

In this study, a facile and eco-friendly freeze-thawing strategy was used to create a physically crosslinked poly(amidoxime)-chitosan hybrid hydrogel with excellent uranium uptake capacity and good biofouling-resistant activity. The hydrogel showed superior uranium uptake capacity and antibacterial property, making it an efficient adsorbent for uranium recovery from seawater.