Application of Zero-Valent Iron Nanoparticles for the Removal of Aqueous Zinc Ions under Various Experimental Conditions

Application of zero-valent iron nanoparticles (nZVI) for Zn(2+) removal and its mechanism were discussed. It demonstrated that the uptake of Zn(2+) by nZVI was efficient. With the solids concentration of 1 g/L nZVI, more than 85% of Zn(2+) could be removed within 2 h. The pH value and dissolved oxygen (DO) were the important factors of Zn(2+) removal by nZVI. The DO enhanced the removal efficiency of Zn(2+). Under the oxygen-contained condition, oxygen corrosion gave the nZVI surface a shell of iron (oxy)hydroxide, which could show high adsorption affinity. The removal efficiency of Zn(2+) increased with the increasing of the pH. Acidic condition reduced the removal efficiency of Zn(2+) by nZVI because the existing H(+) inhibited the formation of iron (oxy)hydroxide. Adsorption and co-precipitation were the most likely mechanism of Zn(2+) removal by nZVI. The FeOOH-shell could enhance the adsorption efficiency of nZVI. The removal efficiency and selectivity of nZVI particles for Zn(2+) were higher than Cd(2+). Furthermore, a continuous flow reactor for engineering application of nZVI was designed and exhibited high removal efficiency for Zn(2+).