Electron pulse radiolysis determination of hydroxyl radical rate constants with Suwannee river fulvic acid and other dissolved organic matter isolates

Paul Westerhoff, Stephen P. Mezyk, William J. Cooper, Daisuke Minakata

Research output: Contribution to journalArticlepeer-review

237 Scopus citations

Abstract

Pulse radiolysis experiments were conducted on dissolved organic matter (DOM) samples isolated as hydrophobic and hydrophilic acids and neutrals from different sources (i.e., stream, lake, wastewater treatment plant). Absolute bimolecular reaction rate constants forthe reaction of hydroxyl radicals ( OH) with DOM (k•OH, DOM) were determined. k•OH, DOM values are expressed as moles of carbon. Based on direct measurement of transient DOM radicals (DOM•) and competition kinetic techniques, both using pulse radiolysis, the k•OH, DOM value for a standard fulvic acid from the Suwannee River purchased from the International Humic Substances Society was (1.60 ± 0.24) × 10 8 M-1 s-1. Both pulse radiolysis methods yielded comparable k•OH, DOM values. The k• OH, DOM values for the seven DOM isolates from different sources ranged from 1.39 × 108 M-1 s-1 to 4.53 × 108 M-1 s-1, and averaged 2.23 × 108 M-1 s-1 (equivalentto 1.9 × 10 4(mgC/L)-1 s-1). These values represent the first direct measurements of k•OH, DOM, and they compare well with literature values obtained via competition kinetic techniques during ozone or ultraviolet irradiation experiments. More polar, lower-molecular-weight DOM isolates from wastewater have higher k•OH, DOM values. In addition, the formation (microsecond time scale) and decay (millisecond time scale) of DOM transients were observed forthe first time. DOM from hydrophobic acids exhibited broader absorbance spectra than transphilic acids, while wastewater DOM isolates had narrower DOM spectra more skewed toward shorter wavelengths than did DOM spectra for hydrophobic acids.

Original languageEnglish (US)
Pages (from-to)4640-4646
Number of pages7
JournalEnvironmental Science and Technology
Volume41
Issue number13
DOIs
StatePublished - Jul 1 2007

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Fingerprint Dive into the research topics of 'Electron pulse radiolysis determination of hydroxyl radical rate constants with Suwannee river fulvic acid and other dissolved organic matter isolates'. Together they form a unique fingerprint.

Cite this