Phytic acid functionalized MOF-808 for seawater uranium extraction with high capacity and selectivity

The efficient extraction of uranium from seawater plays an important role to guarantee a sustainable nuclear energy industry. Zr-based metal-organic frameworks (MOFs) are promising uranium adsorbents due to their high stability, customizable functionality and adjustable topological structure. In this study, Zr based MOF-808 with tunable phytic acid (PA) functionalization (MOF-808-PA1 and MOF-808-PA2) were prepared. The modulation of PA modification significantly promoted the uranium extraction of MOF-808 with the saturated adsorption capacity reaching 423.89 mg/g and adsorption equilibrium achieved in 15 min in aqueous solution. Impressively, MOF-808-PA2 exhibited superior selectivity towards uranium with the distribution coefficient up to 9.2 × 10 5  mL/g, which overwhelms other competitive ions in simulated seawater. After adsorption in real seawater for 28 days, uranium capture capacity of MOF-808-PA2 reached 7.85 mg/g, 8 times higher than that of vanadium. DFT simulation indicated that the excellent seawater uranium extraction performance originated from the strong affinity between abundant P-O/P=O and uranyl ions. This work highlights the design of high-performance uranium adsorbents based on functional group modification in MOFs system.