Response to Comment on 'Oxidation of Sulfoxides and Arsenic(lll) in Corrosion of Nanoscale Zero Valent Iron by Oxygen: Evidence against Ferryl Ions (Fe(IV)) as Active Intermediates in Fenton Reaction'

摘要

In a recent article/ we have developed a method using several sulfoxides as indicators to distinguish between HO* and Fe(lV), based on the finding that Fe(lV) species could react with these compounds through a 2-electron transfer step producing corresponding sulfones, which markedly differed from their HO"-involved products. By measuring the oxidation products of these sulfoxides, we tested the hypothesis that the nature of the oxidants produced during the corrosion of nanoscale zerovalent iron (nZVI or Fe ) by oxygen (O_2) via the Fenton reaction changed with pH from HO" at low pH to a less reactive species Fe(lV) at neutral pH values. However, the finding that no sulfone products were generated in the nZVI/O_2 system over a wide pH range allowed us definitely ruling out Fe (IV) as an active Fenton intermediate. We gratefully appreciate the critical comments of Remucal et al2 on our article and welcome the opportunity to respond. The major point of their arguments was the discrepancy between their data and measured rate constants for Fe(lV) or HO". For the following reasons, however, we believe that this issue held by these authors as the evidence for a "third" oxidant is likely related to the complex reactions of HO". In other words, their data may be reasonably explained by taking peroxyl radical chemistry into account but without assuming a different oxidant rather than Fe(lV) or HO".