A β-ray irradiation resistant MOF-based trap for efficient capture of Th(IV) ion

Efficient capture of radionuclides from aqueous solution is highly essential for environment safety and resource recycling, but still faces large challenge. In this study, a stable aluminum-based metal–organic framework (MOF-303) with high-density ion traps was used to selectively capture thorium (Th) ion from aqueous solution. The features of aluminum center endow this material with excellent resistance from β-ray irradiation even with a high dose of 1000 kGy. Further, due to the special chelation interaction from the ion trap, MOF-303 exhibits a large adsorption capacity for Th(IV) ion (461.7 mg g−1) and excellent separation coefficients up to 97.6, 97.3 and 81.3 for Th(IV)/Pr(III), Th(IV)/Eu(III) and Th(IV)/Nd(III) respectively. The adsorption equilibrium was reached at ∼ 420 min. Besides, the regeneration of MOF-303 as well as the elution of Th(IV) ion can be achieved via an acid-wash process. Experimental and theoretical calculation results indicate Th(IV) ion can be tightly anchored in the ion trap surrounded by six active atoms, via the chemical bonding mode.