Kinetics of zero valent iron nanoparticle oxidation in oxygenated water

Lauren F. Greenlee, Jessica D. Torrey, Robert L. Amaro, Justin M. Shaw

Research output: Contribution to journalArticlepeer-review

119 Scopus citations

Abstract

Zero valent iron (ZVI) nanoparticles are versatile in their ability to remove a wide variety of water contaminants, and ZVI-based bimetallic nanoparticles show increased reactivity above that of ZVI alone. ZVI nanoparticles degrade contaminants through the reactive species (e.g., OH*, H2(g), H2O2) that are produced during iron oxidation. Measurement and modeling of aqueous ZVI nanoparticle oxidation kinetics are therefore necessary to optimize nanoparticle design. Stabilized ZVI and iron-nickel nanoparticles of approximately 150 nm in diameter were synthesized through solution chemistry, and nanoparticle oxidation kinetics were determined via measured mass change using a quartz crystal microbalance (QCM). Under flowing aerated water, ZVI nanoparticles had an initial exponential growth behavior indicating surface-dominated oxidation controlled by migration of species (H2O and O2) to the surface. A region of logarithmic growth followed the exponential growth which, based on the Mott-Cabrera model of thin oxide film growth, suggests a reaction dominated by movement of species (e.g., iron cations and oxygen anions) through the oxide layer. The presence of ethanol or a nickel shell on the ZVI nanoparticles delayed the onset of iron oxidation and reduced the extent of oxidation. In oxygenated water, ZVI nanoparticles oxidized primarily to the iron oxide-hydroxide lepidocrocite.

Original languageEnglish (US)
Pages (from-to)12913-12920
Number of pages8
JournalEnvironmental Science and Technology
Volume46
Issue number23
DOIs
StatePublished - Dec 4 2012

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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