Bio-inspired nano-traps for uranium extraction from seawater and recovery from nuclear waste

TLDR

Nature can efficiently recognize specific ions via second‑sphere interactions on protein scaffolds, yet artificially manipulating such affinity cost‑effectively for large‑scale water samples remains a challenge. The study proposes bio‑inspired nano‑traps that enhance uranyl capture by embedding amidoxime chelators into porous frameworks with assistant groups mimicking biological coordination. The authors construct porous frameworks bearing amidoxime chelators with amino substituents that lower uranyl charge and act as hydrogen‑bond acceptors, as confirmed by spectroscopy, crystallography, and theory calculations. The 2‑aminobenzamidoxime framework sequesters uranium with a capacity of 530 mg g⁻¹ and captures 4.36 mg g⁻¹ from real seawater, outperforming benchmarks.

Abstract

Nature can efficiently recognize specific ions by exerting second-sphere interactions onto well-folded protein scaffolds. However, a considerable challenge remains to artificially manipulate such affinity, while being cost-effective in managing immense amounts of water samples. Here, we propose an effective approach to regulate uranyl capture performance by creating bio-inspired nano-traps, illustrated by constructing chelating moieties into porous frameworks, where the binding motif's coordinative interaction towards uranyl is enhanced by introducing an assistant group, reminiscent of biological systems. Representatively, the porous framework bearing 2-aminobenzamidoxime is exceptional in sequestering high uranium concentrations with sufficient capacities (530 mg g-1) and trace quantities, including uranium in real seawater (4.36 mg g-1, triple the benchmark). Using a combination of spectroscopic, crystallographic, and theory calculation studies, it is revealed that the amino substituent assists in lowering the charge on uranyl in the complex and serves as a hydrogen bond acceptor, boosting the overall uranyl affinity of amidoxime.