TY - JOUR
T1 - Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation
AU - Utsumi, Hideo
AU - Han, Sang Kuk
AU - Ichikawa, Kazuhiro
N1 - Funding Information:
This work is in part supported by Grant-in-Aids for Scientific Research, for Research on Priority Areas. for Cooperative Research, for General Science Research, and for Developmental Scientific Research from the Ministry of Education. Science. Sports and Culture of Japan, by a grant from Tokyu Foundation for Bener Environment and that from Showa Shell Sekiyu Foundation for Promotion of Environmental Research.
PY - 1998
Y1 - 1998
N2 - Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 x 10-6 M of DMPO-OH, indicating that 1.4% of OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.
AB - Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 x 10-6 M of DMPO-OH, indicating that 1.4% of OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.
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U2 - 10.1016/S0273-1223(98)00576-9
DO - 10.1016/S0273-1223(98)00576-9
M3 - Conference article
AN - SCOPUS:0031764681
VL - 38
SP - 147
EP - 154
JO - Water Science and Technology
JF - Water Science and Technology
SN - 0273-1223
IS - 6 pt 5
T2 - Proceedings of the 1998 19th Biennial Conference of the International Association on Water Quality. Part 5 (of 10)
Y2 - 21 June 1998 through 26 June 1998
ER -