Efficient uranium capture by a soybean protein isolate/hydroxyapatite hybrid filtration layer

Biomimetic strategy-derived protein-based materials for uranium adsorption exhibit outstanding selectivity, but corresponding high cost and complicated preparation limits their scale-up application. This study utilizes in situ mineralization to incorporate nano-hydroxyapatite (HAP) into soy protein isolate (SPI) coating, thereby achieving a low-cost and facile strategy to leverage the selective uranium adsorption properties mediated by phosphate groups in HAP. The network structure of SPI facilitates the uniform dispersion of HAP, while the rigid HAP nanoparticles enhance the mechanical properties of the protein film. This synergistic design enables a dual-mechanism adsorption process: HAP first electrostatically preconcentrates U(VI) ions near the interface, followed by strong multidentate coordination with carboxyl and amino groups from SPI. The integrated adsorption mechanism significantly improves uranium capture efficiency while maintaining the cost-effectiveness and process simplicity. Based on this design, the SPI/HAP hybrid coating effectively remove uranium across a pH range of 3.5–9.0, achieving a rejection ratio over 99.1 % and a maximum adsorption capacity of 587.1 mg/g. Moreover, the hybrid material achieved a uranium rejection ratio exceeding 90 % in both simulated salt lake and seawater, while demonstrating exceptional selectivity for uranium over vanadium. Its precision in uranium/vanadium discrimination and interception uranium sequester performance significantly surpass conventional membranes and adsorbents. Furthermore, the SPI/HAP coating is easily regenerated and retained 94.1 % reusability after five cycles. The superior rejection ratio, low cost, environmentally benign nature, and facile preparation of the material, highlight SPI/HAP to be a promising biomass-based material for practical uranium capture in scale-up application.