Efficient reduction and adsorption of U(VI) by TiN-modified zero-valent nickel: mechanistic insights and DFT calculations

The mining of uranium ore and the disposal of nuclear power plant waste may lead to uranium contamination. Particularly in aquatic environments, uranium exhibits high solubility and mobility, thereby causing severe radioactive pollution to groundwater, soil, and ecosystems. Such contamination poses significant challenges for remediation efforts. In this study, we synthesized a composite material (Ni-TiN) composed of nano-titanium nitride (TiN) and zero-valent nickel using an in-situ reduction method, achieving efficient uranium adsorption and reduction. The experimental results demonstrated that under the conditions of 303 K and pH = 5, the maximum uranium adsorption capacity reached 418.97 mg/g, accompanied by a significant enhancement in the removal rate. The experimental data perfectly fit the pseudo-second-order kinetic model. Combined with density functional theory (DFT) calculations, this indicates that the removal process of U(VI) by the composite material involves a combination of chemical reduction and complexation, further elucidating its adsorption mechanism. In the presence of multiple ions, only a few ions significantly inhibited U(VI) removal. These findings suggest that Ni-TiN exhibits exceptional environmental adaptability and selective adsorption capacity, highlighting its significant potential in the field of environmental remediation.