The inherent features of covalent organic frameworks (COFs) make them highly attractive for uranium recovery applications. A key aspect yet to be explored is how to improve the selectivity and efficiency of COFs for recovering uranium from seawater. To achieve this goal, a series of robust and hydrophilic benzoxazole-based COFs is developed (denoted as Tp-DBD, Bd-DBD, and Hb-DBD) as efficient adsorbents for photo-enhanced targeted uranium recovery. Benefiting from the hydroxyl groups and the formation of benzoxazole rings, the hydrophilic Tp-DBD shows outstanding stability and chemical reduction properties. Meanwhile, the synergistic effect of the hydroxyl groups and the benzoxazole rings in the π-conjugated frameworks significantly decrease the optical band gap, and improve the affinity and capacity to uranium recovery. In seawater, the adsorption capacity of uranium is 19.2× that of vanadium, a main interfering metal in uranium extraction.
Keywords: chemical reduction; covalent organic frameworks; photocatalytic; photothermal; uranium recovery.
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