Formation-of ferrihydrite and associated iron corrosion products in permeable reactive barriers of zero-valent iron

Yoko Furukawa, Jin-Wook Kim, Janet Watkins, Richard T. Wilkin

Research output: Contribution to journalArticle

231 Citations (Scopus)

Abstract

Ferrihydrite, which, is known to form in the presence of oxygen and to be stabilized by the adsorption of Si, PO4 and SO4, is ubiquitous in the fine-grained fractions of permeable reactive barrier (PRB) samples from the U.S. Coast Guard Support Center (Elizabeth City, NC) and the Denver Federal Center (Lakewood, CO) studied by high-resolution transmission electron microscopy and selected area electron diffraction. The concurrent energy-dispersive X-ray data indicate a strong association between ferrihydrite and metals such as Si, Ca, and Cr. Magnetite, green rust 1, aragonite, calcite, mackinawite, greigite and lepidocrocite were also present, indicative of a geochemical environment that is temporally and spatially heterogeneous. Whereas magnetite, which is known to form due to anaerobic Fe0 corrosion, passivates the Fe0 surface, ferrihydrite precipitation occurs away from the immediate Fe0 surface forming small (<0. μm) discrete clusters. Consequently, Fe0-PRBs may remain effective for a longer period of time in slightly oxidized groundwater systems where ferrihydrite formation occurs compared to oxygen-depleted systems where magnetite passivation occurs. The ubiquitous presence of ferrihydrite suggests that the use of Fe0-PRBs may be extended to applications that require contaminant adsorption rather than, or in addition to redox-promoted contaminant degradation.

Original languageEnglish
Pages (from-to)5469-5475
Number of pages7
JournalEnvironmental Science and Technology
Volume36
Issue number24
DOIs
Publication statusPublished - 2002 Dec 15

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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