Removal of U (VI) from acidic and alkaline aqueous solutions by zero-valent iron nanoparticles

Removal of uranium (VI) from aqueous solutions by zero-valent iron nanoparticles (nZVI) was investigated in both acidic and alkaline solutions in absence and presence of counter-ions (0.1 M NaNO₃). Langmuir and Freundlich equations were applied to model the sorption isotherms whereas the data obtained at 15, 25, 35 and 45 °C from the kinetic experiments were successfully reproduced by a pseudo-second order equation and used for calculation of thermodynamic parameters. Electron microscopy (SEM/EDS), X-ray photoelectron spectroscopy and UV-Fluorescence were applied to explore possible mechanisms. The U-removal seems to be due mainly to sorption followed by U(VI) reduction.