Ultratrace Uranium Removal by Covalent Organic Frameworks on an In-Situ-Decorated Sponge as Integral Materials

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Herein, a sulfonated covalent organic framework (COF-SO 3 H) is prepared in situ on melamine sponge (MS) to produce MS@COF-SO 3 H as integral materials by a one-pot synthesis in water at room temperature, for facile deep removal of trace uranium-containing wastewater. The −SO 3 H on the COFs is able to form complexation with UO 2 2+ through strong coordination interactions, and MS@COF-SO 3 H is therefore highly selective for UO 2 2+ ( K d = 52603 mL g –1 ). The adsorption efficiency of MS@COF-SO 3 H-3 can reach 97.9% and 87.5% when the initial UO 2 2+ concentration is 100 and 5 μg L –1, respectively, and the minimum residual UO 2 2+ concentration is as low as 0.478 μg L –1, far lower than that in previous reports. In addition, MS@COF-SO 3 H exhibits excellent durability as an adsorbent, and its adsorption efficiency for UO 2 2+ is still as high as 92.4% even after 5 cycles of recycling. The mild preparation conditions and excellent performance of MS@COF-SO 3 H make it quite promising as a highly efficient adsorbent for uranium removal. This work provides an important clue to prepare adsorbents facilely for nuclear wastewater deep treatment.