Immobilization of U(VI) on Hierarchical NiSiO@MgAl and NiSiO@NiAl Nanocomposites from Wastewater

Abstract

The emerging radioactive pollution caused by human activity has attracted increasing attention in the recent years. Uranium (U(VI)) is one of the key radionuclides in the environment, but its migration behavior is firmly controlled by the sorption properties on the environmental matrix. Herein, three hollow spherical materials (NiSiO, NiSiO@MgAl, and NiSiO@NiAl) were rationally designed and constructed by the template method, which showed great potential in the immobilization of U(VI). The engineered functional nanomaterials exhibited fast sorption kinetics, which could be illustrated by the pseudo-second-order model, and favorable thermodynamics, which showed a spontaneous and endothermic process. On the basis of the batch experimental investigations under different conditions, the immobilization of U(VI) on the as-synthesized nanomaterials followed the monolayer mechanism in the form of innersphere surface complexes. The maximum removal capacity (Qmax) of U(VI) on NiSiO@NiAl (136.94 mg g–1) was much higher than those of NiSiO@MgAl (41.82 mg g–1) and NiSiO (14.77 mg g–1). The XPS investigations revealed that the excellent sorption property of NiSiO@NiAl originated from its surface Ni–OH group, which had higher coordination ability toward U(VI) than the others. This work paves an avenue to rational design and synthesis of novel materials in the application of radionuclide pollution treatment.