| Abstract
| - Addition of nanoparticulate zero-valent iron (nZVI) tooxygen-containing water results in oxidation of organiccompounds. To assess the potential application of nZVI foroxidative transformation of organic contaminants, theconversion of benzoic acid (BA) to p-hydroxybenzoic acid(p-HBA) was used as a probe reaction. When nZVI wasadded to BA-containing water, an initial pulse of p-HBA wasdetected during the first 30 min, followed by the slowgeneration of additional p-HBA over periods of at least 24h. The yield of p-HBA increased with increasing BAconcentration, presumably due to the increasing ability ofBA to compete with alternate oxidant sinks, such asferrous iron. At pH 3, maximum yields of p-HBA duringthe initial phase of the reaction of up to 25% were observed.The initial rate of nZVI-mediated oxidation of BA exhibiteda marked reduction at pH values above 3. Despite thedecrease in oxidant production rate, p-HBA was observedduring the initial reaction phase at pH values up to 8.Competition experiments with probe compounds expectedto exhibit different affinities for the nZVI surface (phenol,aniline, o-hydroxybenzoic acid, and synthetic humic acids)indicated relative rates of reaction that were similar tothose observed in competition experiments in which hydroxylradicals were generated in solution. Examination of theoxidizing capacity of a range of Fe0 particles reveals acapacity in all cases to induce oxidative transformation ofbenzoic acid, but the high surface areas that can beachieved with nanosized particles renders such particlesparticularly effective oxidants.
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