Remediation of U(VI)-contaminated water using zero-valent iron

We investigated the possibility of U(VI) reduction by zero-valent iron (Fe-0). We conducted batch experiments with granular iron and solutions containing 0.25 and 9.3 mg L-1 U(VI) at 24 degrees C. The solution pH ranges between 2 and 9. In all experiments uranium removal was complete within several hours to several days regardless of the pH value. The reduced uranium precipitated as poorly crystallized hydrated uraninite, UO2.nH(2)O. The reduction of U(VI) to U(IV) by Fe-0 was found to be the principal mechanism of U removal from the solution. Other mechanisms such as U(VI) sorption on the newly formed Fe(III) hydroxides are insignificant. These results show that zero-valent iron can be used to remediate U-contaminated waters from uranium mines and mill tailings sites, the pH of which usually ranges between 2 and 9. ((C) Academie des sciences / Elsevier, Paris).