Characterization of colored products formed during irradiation of aqueous solutions containing H2O2 and phenolic compounds

Jonathan L. Chang, Jonathan E. Thompson

Research output: Contribution to journalArticlepeer-review

122 Scopus citations

Abstract

Irradiation of aqueous (pH = 5) mixtures containing hydrogen peroxide (1 mM) and phenolic compounds (10 mM) were found to produce visible light absorbing solutions over the course of several hours. The kinetics and products of these reactions were studied by UV-VIS absorbance, electrospray mass spectrometry, FTIR, fluorescence, and NMR and compared to humic-like substances commonly found in atmospheric particulate matter. It was determined the reactions leading to formation of color are quite general to this compound class, and the reactions proceeded more rapidly with hydroxyl or methoxy substitution ortho to the phenolic OH. However, para substitution generally slowed formation of colored compounds compared to the unsubstituted form. Mass spectrometry confirms compounds of several hundred Da formed in the reaction mixtures. The IR spectra of the reaction products bear similarity to that observed for authentic aerosol humic-like substances. The results indicate radical coupling of phenols and methoxylated phenols in tropospheric waters may contribute to humic-like particulate matter.

Original languageEnglish
Pages (from-to)541-551
Number of pages11
JournalAtmospheric Environment
Volume44
Issue number4
DOIs
StatePublished - Feb 2010

Keywords

  • Airborne particulate matter
  • Brown carbon
  • Humic-like substances (HULIS)
  • Light absorbing carbon
  • OH radical

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