High-strength double-network poly (acrylamide-acrylic acid) hydrogel synergistic with UiO-66-NH-AO in wastewater

Efficient recovery of uranium from radioactive wastewater significantly has far-reaching positive implications for both the recycling of uranium resources and environmental conservation. In this work, a new stable hydrogel/MOFs composite with potential for efficient uranium capture has been developed. A double network structure was formed through the chemical covalent crosslinking of poly (acrylamide-acrylic acid) and the physical crosslinking of agar. The rapid self-crosslinking of agar not only enables the uniform dispersion of Metal-Organic Frameworks (MOFs) nanoparticles but also promotes the hydrogel to possess exceptional tensile strength and low swelling ratio, whereas the incorporation of amidoximated MOFs enhances the selectivity for uranium. The composite achieved a uranium-uptake capacity of 275.42 mg/g (298 K, C₀ = 120 mg/L, pH = 6), and it retains reproducible and stable after five cycles, while exhibiting high selectivity for uranyl, even amidst ten competing metal ions. Moreover, the uranium removal rate reached 93 % within three days in low concentration simulated nuclear wastewater. Multiple spectral analyses coupled with theoretical calculations confirmed that the mechanism of U(VI) capture involves intraparticle diffusion, along with the coordination of amidoxime, carboxyl, and amino groups. This research offers a valuable reference for the development of composite materials to treat radioactive effluent.