Bioinspired electrostatic layer-by-layer assembly membranes constructed based on mild strategy for uranium extraction from seawater

Developing simple and efficient new strategies for uranium extraction from seawater (UES) is crucial for addressing the energy crisis. Here, we proposed a mild strategy to prepare a layer-by-layer assembly membrane (LAM) by polydopamine (PDA) and polyethyleneimine (PEI) co-deposition coupled with polyethyleneimine/phytic acid self-assembly for efficient uranium extraction. By regulating the number of self-assemblies, the performance of the membrane could be easily adjusted. The functional coating's rich active groups (–NH₂, -PO₄^3-, –OH) provided a good adsorption performance for the modified membrane, with a static adsorption capacity of 142.25 mg·g⁻¹. Meanwhile, it possessed excellent dynamic removal rate, which could achieve over 90 % uranium removal within 90 min. The LAM also exhibited exceptional adsorption selectivity, boasting a remarkable 9:1 ratio in extracting uranium and vanadium. Furthermore, the strong adhesion of PDA endowed the material with good stability, and the adsorption capacity only decreased by 23 % after 5 cycles. DFT calculations proved that PEI/PA-U was the most stable model. Particularly, the adsorption capacity of LAM in natural seawater can reach 0.99 mg·g⁻¹. With the simple and mild preparation process, along with the excellent adsorption performance, the LAM membrane holds great promise for seawater uranium enrichment.