Removal of U(VI) in Aqueous Solution by Nanoscale Zero-Valent Iron(nZVI)

The nanoscale zero-valent iron (nZVI) was synthesized by reduction of ferric chloride with sodium borohydride and characterized by SEM and XRD. The removal of U(VI) from aqueous solution by nZVI was investigated. The paper investigates the influence factors such as solution pH, initial U(VI) concentration, contact time and temperature on removal of U(VI) by nZVI with batch experiments and discusses the reduction kinetics characteristic. The results showed that U(VI) can be effectively removed from aqueous solution by nZVI, the reduction process followed the pseudo first-order kinetics. The apparent rate constant was proportional to nZVI concentration. The temperature had certain effect on removal of U(VI), the apparent rate constant increased with increase in temperature. The reaction activation energy E-a was 28.5 +/- 0.435 kJ/mol, which was below the ordinary chemical reaction activation energy (60 +/- 250 kJ/mol), so the reaction was easy to take place. The pH value had significant influence on the removal of U(VI), weakly acidic conditions were favorable to the removal of U(VI). For the fast reaction kinetics and high U(VI) removal capacity, nZVI has the potential to become an effective remedial agent for in situ remediation of uraniumcontaminated soil and groundwater.