Oxidizing Capacity of Periodate Activated with Iron-Based Bimetallic Nanoparticles

Abstract

Nanosized zerovalent iron (nFe(0)) loaded with a secondary metal such as Ni or Cu on its surface was demonstrated to effectively activate periodate (IO4-) and degrade selected organic compounds at neutral pH. The degradation was accompanied by a stoichiometric conversion of IO4- to iodate (IO3-). nFe(0) without bimetallic loading led to similar IO4- reduction but no organic degradation, suggesting the production of reactive iodine intermediate only when IO4- is activated by bimetallic nFe(0) (e.g., nFe(0)-Ni and nFe(0)-Cu). The organic degradation kinetics in the nFe(0)-Ni(or Cu)/IO4- system was substrate dependent: 4-chlorophenol, phenol, and bisphenol A were effectively degraded, whereas little or no degradation was observed with benzoic acid, carbamazepine, and 2,4,6-trichlorophenol. The substrate specificity, further confirmed by little kinetic inhibition with background organic matter, implies the selective nature of oxidant in the nFe(0)-Ni(or Cu)IO4- system. The comparison with the photoactivated IO4- system, in which iodyl radical (IO3 center dot) is a predominant oxidant in the presence of methanol, suggests IO3 center dot also as primary oxidant in the nFe(0)-Ni(or Cu)/IO4- system.