| Abstract
| - Most studies on zerovalent iron (ZVI) were mainlyfocused on the reductive transformation of halo- or nitro-compounds. Oxidation reactions occurring on ZVI havebeen recently recognized. In this study, we demonstratethat the oxidation pathways on ZVI can be accelerated bythe presence of polyoxometalate (POM: nanosized metal−oxygen cluster anion) serving as an electron shuttle. Theions, SiW12O404- and PW12O403-, can mediate the electrontransfer from the Fe0 surface to O2 while enhancing theproduction of H2O2, which subsequently initiates the OHradical-mediated oxidation through a Fenton-type reaction.The oxidation reaction was completely quenched byadding methanol as an OH radical-scavenger. On the otherhand, PMo12O403- completely inhibited the oxidativedegradation by irreversibly scavenging an electron andholding it. We systematically investigated the effects of ironloading, the concentration of POM, and pH on theoxidative degradation kinetics of 4-chlorophenol in the POM-mediated ZVI system. The POM-mediated oxidations onZVI were additionally tested for 12 organic contaminantsand the rates were compared. Their oxidative degradationon ZVI was mostly enhanced in the presence of POM(SiW12O404-). The present study provides a good modelsystem upon which the ZVI-based oxidation technologiescan be successfully enhanced and modified for furtherdevelopments.
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