Unexpected ultrafast and high adsorption of U(VI) and Eu(III) from solution using porous Al2O3 microspheres derived from MIL-53

Uranium, a kind of strategic resource for nuclear energy, is inevitably released into environment because of nuclear fuel fabrication and ore mining. Although numerous traditional materials have been applied for the removal of radionuclides, the integrating advantages of ultrafast adsorption kinetics and high adsorption capacity are still an extreme challenge. Herein we reported a facile strategy for fabricating a novel porous Al2O3 microsphere (P-Al2O3 MSs) by the calcination of metal-organic frameworks (MIL-53(Al)) and applied it to immobilize radionuclides from wastewater. The resulting P-Al2O3 MSs inherited the morphology of MIL-53(Al) and manifested a mesoporous structure with high specific area (similar to 248.57m(2).g(-1)). Kinetic analyses denoted that U(VI)/Eu(III) adsorption onto P-Al2O3 MSs achieved equilibrium within 25 min, much shorter than the commercial gamma-Al2O3 nanomaterials. The calculated maximum adsorption amounts of P-Al2O3 MSs at 298 K reached 316.87 mg.g(-1) for U(VI) (pH= 5.0) and achieved 223.37 mg.g(-1) for Eu(III) (pH= 6.0), much higher than gamma-Al2O3 and most of other functionalized metal oxides. XPS analysis indicated that the hydroxy groups played a necessary part role for the binding of U(VI) and Eu(III) to P-Al2O3 MSs. Moreover, the excellent adsorption capabilities for U(VI) and Eu(III) in natural or synthetic waters further confirmed the practical application of P-Al2O3 MSs in real wastewater treatment.