Effect of Cr(VI) concentration on gas and particle production during iron oxidation in aqueous solutions containing Cl ions

Hyangsig Ahn, Ho Young Jo, Ji Hun Ryu, Yong Kwon Koh

Research output: Contribution to journalArticle

Abstract

Zero-valent iron (ZVI) is commonly used as a medium in permeable reactive barriers (PRBs) because of its high reducing ability. The generation of H2 gas in PRBs, however, can decrease the permeability of PRBs and reduce the contact area between the PRB and contaminated groundwater. This study investigated the effect of the initial Cr(VI) concentration ([Cr(VI)init]) in aqueous solutions containing Cl ions on the generation of H2 gas. ZVI chips were reacted in reactors with 0.5-M NaCl solutions with [Cr(VI)init] ranging between 51 and 303 mg/L. The initial pH was set at 3. The oxidation of ZVI chips by Cr(VI) in aqueous solutions containing Cl ions produced H2 gas and particles (Fe(III)–Cr(III)(oxy)hydroxides). The Cr(VI) removal from aqueous solutions increased as the [Cr(VI)init] increased, as did H2 gas generation. The positive effect of [Cr(VI)init] on H2 gas generation might be due to an increase in the redox potential gradient as [Cr(VI)init] increases. This increased gradient would enhance H+ ion penetration through the passive film (Fe(III)–Cr(III)(oxy)hydroxides), which formed on the ZVI surface, by diffusion from the solution to pits beneath the passive film.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalEnvironmental Technology (United Kingdom)
DOIs
Publication statusAccepted/In press - 2016 Jun 24

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Keywords

  • chromium
  • hydrogen gas
  • Iron
  • oxidation
  • reduction

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Water Science and Technology

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