Oxidizing capacity of periodate activated with iron-based bimetallic nanoparticles

Abstract

Nanosized zerovalent iron (nFe0) 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 nFe0 (e.g., nFe0-Ni and nFe0-Cu). The organic degradation kinetics in the nFe0-Ni(or Cu)/IO 4 - 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 nFe0-Ni(or Cu)/IO4 - system. The comparison with the photoactivated IO4 - system, in which iodyl radical (IO3 •) is a predominant oxidant in the presence of methanol, suggests IO3 • also as primary oxidant in the nFe0-Ni(or Cu)/IO4 - system.