Modeling the Kinetics of Hydrogen Formation by Zerovalent Iron: Effects of Sulfidation on Micro- and Nano-Scale Particles

Hejie Qin, Xiaohong Guan, Joel Z. Bandstra, Richard Johnson, Paul Tratnyek

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The hydrogen evolution reaction (HER) that generates H2 from the reduction of H2O by Fe0 is among the most fundamental of the processes that control reactivity in environmental systems containing zerovalent iron (ZVI). To develop a comprehensive kinetic model for this process, a large and high-resolution data set for HER was measured using five types of ZVI pretreated by acid-washing and/or sulfidation (in pH 7 HEPES buffer). The data were fit to four alternative kinetic models using nonlinear regression analysis applied to the whole data set simultaneously, which allowed some model parameters to be treated globally across multiple experiments. The preferred model uses two independent reactive phases to match the two-stage character of most HER data, with rate constants (k's) for each phase fitted globally by iron type and phase quantities (S's) fitted as fully local (independent) parameters. The first, faster stage was attributed to a reactive mineral intermediate (RMI) phase like Fe(OH)2, which may form in all experiments during preequilibration, but is rapidly consumed, leaving the second, slower stage of HER, which is due to reaction of Fe0. In addition to providing a deterministic model to explain the kinetics of HER by ZVI over a wide range of conditions, the results provide an improved quantitative basis for comparing the effects of sulfidation on ZVI.

Original languageEnglish (US)
Pages (from-to)13887-13896
Number of pages10
JournalEnvironmental Science and Technology
Volume52
Issue number23
DOIs
StatePublished - Dec 4 2018

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Hydrogen
Iron
hydrogen
iron
kinetics
Kinetics
modeling
HEPES
Washing
Regression analysis
Process control
Minerals
Rate constants
regression analysis
Buffers
experiment
Experiments
effect
particle
Acids

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Modeling the Kinetics of Hydrogen Formation by Zerovalent Iron : Effects of Sulfidation on Micro- and Nano-Scale Particles. / Qin, Hejie; Guan, Xiaohong; Bandstra, Joel Z.; Johnson, Richard; Tratnyek, Paul.

In: Environmental Science and Technology, Vol. 52, No. 23, 04.12.2018, p. 13887-13896.

Research output: Contribution to journalArticle

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