Quantitative analysis for the enhancement of hydroxyl radical generation by phenols during ozonation of water

Sang Kuk Han, Kazuhiro Ichikawa, Hideo Utsumi

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Generation of hydroxyl radical, one of the major reactive species in the ozonation of water, was directly and quantitatively measured with the combination technique of spin-trapping, stopped flow and electron spin resonance (ESR) spectroscopy. Hydroxyl radical in ozonated water was trapped with 5,5-dimethyl-pyrrolidine-1-oxyl (DMPO) as a stable radical, DMPO-OH, and the amount of DMPO-OH was quantitatively measured with an ESR spectrometer. The ESR signal of DMPO-OH increased linearly with increasing ozone and 1 M ozone produced 0.011 M DMPO-OH, if one molecule of ozone produces one molecule of .OH. The kinetics of DMPO:OH generation was determined with a stopped-flow/ESR method and analyzed by two different methods. The logarithmic plot of the initial velocity of DMPO-OH generation vs the ozone concentration gave a linear relationship, which was expressed as v0 (M s-1) = 8.7 x 101 x [O3 (M)]2.25. The rate constant of DMPO-OH generation, 8.7 x 101 M-1.25 s-1, is close to the reaction constant of ozone with an hydroxide ion. The decomposition rate of ozone to .OH was estimated to be 0.026 s-1 at 40 μM aqueous ozone from the semilogarithmic plot of the amount of DMPO-OH against reaction time. The presence of phenol derivatives increased both the generation rate and the final amount of DMPO-OH in a dose dependent manner. The enhancing effect of phenols on .OH generation was also analyzed with the above two methods, the decomposition of ozone and the generation of DMPO-OH. The effect depended on the kind, position and number of substituents of phenol. The chlorine substitution of phenol had a more enhancing effect than that of methyl substitution and the ortho-substitution by chlorine showed a stronger enhancement. 2,4-Dichlorophenol showed the strongest enhancing effect on .OH generation among phenols examined, followed by 2-chlorophenol.

Original languageEnglish
Pages (from-to)3261-3266
Number of pages6
JournalWater Research
Volume32
Issue number11
DOIs
Publication statusPublished - Nov 1 1998

All Science Journal Classification (ASJC) codes

  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

Fingerprint Dive into the research topics of 'Quantitative analysis for the enhancement of hydroxyl radical generation by phenols during ozonation of water'. Together they form a unique fingerprint.

  • Cite this