Dendritic hierarchical porous photothermal composite hydrogels based on directional freezing for highly efficient uranium extraction

Abstract

As the demand for clean energy increases, extracting uranium from seawater has emerged as a vital solution to address fuel shortages. Nevertheless, practical applications encounter various challenges, including the low presence of uranyl ions and the interference caused by competing ions. To address these issues, a photothermal composite hydrogel (PAO/PEI@M) featuring a dendritic hierarchical porous structure was synthesized through directional freezing, enabling efficient recovery and selective extraction of uranium from seawater. This hydrogel exhibits excellent hydrophilicity, swelling capacity, and thermal stability, meanwhile, the photothermal conversion properties of MXene significantly enhance the selective adsorption of uranium by PAO. Adsorption experiments show that after the uniform coating and light-induced heating of the hydrogel surface, its uranium adsorption capacity reaches 395.26 mg·g⁻¹ while maintaining high selectivity. After six cycles of adsorption and desorption, the PAO/PEI@M hydrogel maintains a high uranium adsorption capacity of 250.87 mg·g⁻¹. In simulated seawater, the PAO/PEI@M hydrogel demonstrates excellent uranium removal efficiency and selectivity. Overall, the PAO/PEI@M hydrogel show promising application prospects for the selective enrichment of uranium from seawater.