Chlorite formation during ClO 2 oxidation of model compounds having various functional groups and humic substances

Wenhui Gan, Sirong Huang, Yuexian Ge, Tom Bond, Paul Westerhoff, Jiaxin Zhai, Xin Yang

Research output: Contribution to journalArticle

Abstract

Chlorine dioxide (ClO 2 ) has been used as an alternative to chlorine in water purification to reduce the formation of halogenated by-products and give superior inactivation of microorganisms. However, the formation of chlorite (ClO 2 ) is a major consideration in the application of ClO 2 . In order to improve understanding in ClO 2 formation kinetics and mechanisms, this study investigated the reactions of ClO 2 with 30 model compounds, 10 humic substances and 2 surface waters. ClO 2 yields were found to be dependent on the distribution of functional groups. ClO 2 oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO 2 yields >50%, while oxidation of olefins, thiols and benzoquinones had ClO 2 yields <50%. ClO 2 yields from humic substances depended on the ClO 2 dose, pH and varied with different reaction intervals, which mirrored the behavior of the model compounds. Phenolic moieties served as dominant fast-reacting precursors (during the first 5 min of disinfection). Aromatic precursors (e.g., non-phenolic lignins or benzoquinones) contributed to ClO 2 formation over longer reaction time (up to 24 h). The total antioxidant capacity (indication of the amount of electron-donating moieties) determined by the Folin-Ciocalteu method was a good indicator of ClO 2 -reactive precursors in waters, which correlated with the ClO 2 demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO 2 at equivalent ClO 2 exposure, but the prediction in natural water should be conservative.

Original languageEnglish (US)
Pages (from-to)348-357
Number of pages10
JournalWater Research
Volume159
DOIs
StatePublished - Aug 1 2019

Fingerprint

humic substance
Functional groups
functional group
chlorite
oxidation
Oxidation
antioxidant
chlorine
Water
Antioxidants
Chlorine
Bearings (structural)
water
thiol
disinfection
lignin
Disinfection
Lignin
Surface waters
microorganism

Keywords

  • Chlorate
  • Chlorine dioxide (ClO )
  • Chlorite
  • Disinfection by-products
  • Water treatment

ASJC Scopus subject areas

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

Cite this

Chlorite formation during ClO 2 oxidation of model compounds having various functional groups and humic substances . / Gan, Wenhui; Huang, Sirong; Ge, Yuexian; Bond, Tom; Westerhoff, Paul; Zhai, Jiaxin; Yang, Xin.

In: Water Research, Vol. 159, 01.08.2019, p. 348-357.

Research output: Contribution to journalArticle

Gan, Wenhui ; Huang, Sirong ; Ge, Yuexian ; Bond, Tom ; Westerhoff, Paul ; Zhai, Jiaxin ; Yang, Xin. / Chlorite formation during ClO 2 oxidation of model compounds having various functional groups and humic substances In: Water Research. 2019 ; Vol. 159. pp. 348-357.
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abstract = "Chlorine dioxide (ClO 2 ) has been used as an alternative to chlorine in water purification to reduce the formation of halogenated by-products and give superior inactivation of microorganisms. However, the formation of chlorite (ClO 2 − ) is a major consideration in the application of ClO 2 . In order to improve understanding in ClO 2 − formation kinetics and mechanisms, this study investigated the reactions of ClO 2 with 30 model compounds, 10 humic substances and 2 surface waters. ClO 2 − yields were found to be dependent on the distribution of functional groups. ClO 2 oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO 2 − yields >50{\%}, while oxidation of olefins, thiols and benzoquinones had ClO 2 − yields <50{\%}. ClO 2 − yields from humic substances depended on the ClO 2 dose, pH and varied with different reaction intervals, which mirrored the behavior of the model compounds. Phenolic moieties served as dominant fast-reacting precursors (during the first 5 min of disinfection). Aromatic precursors (e.g., non-phenolic lignins or benzoquinones) contributed to ClO 2 − formation over longer reaction time (up to 24 h). The total antioxidant capacity (indication of the amount of electron-donating moieties) determined by the Folin-Ciocalteu method was a good indicator of ClO 2 -reactive precursors in waters, which correlated with the ClO 2 demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO 2 − at equivalent ClO 2 exposure, but the prediction in natural water should be conservative.",
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N2 - Chlorine dioxide (ClO 2 ) has been used as an alternative to chlorine in water purification to reduce the formation of halogenated by-products and give superior inactivation of microorganisms. However, the formation of chlorite (ClO 2 − ) is a major consideration in the application of ClO 2 . In order to improve understanding in ClO 2 − formation kinetics and mechanisms, this study investigated the reactions of ClO 2 with 30 model compounds, 10 humic substances and 2 surface waters. ClO 2 − yields were found to be dependent on the distribution of functional groups. ClO 2 oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO 2 − yields >50%, while oxidation of olefins, thiols and benzoquinones had ClO 2 − yields <50%. ClO 2 − yields from humic substances depended on the ClO 2 dose, pH and varied with different reaction intervals, which mirrored the behavior of the model compounds. Phenolic moieties served as dominant fast-reacting precursors (during the first 5 min of disinfection). Aromatic precursors (e.g., non-phenolic lignins or benzoquinones) contributed to ClO 2 − formation over longer reaction time (up to 24 h). The total antioxidant capacity (indication of the amount of electron-donating moieties) determined by the Folin-Ciocalteu method was a good indicator of ClO 2 -reactive precursors in waters, which correlated with the ClO 2 demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO 2 − at equivalent ClO 2 exposure, but the prediction in natural water should be conservative.

AB - Chlorine dioxide (ClO 2 ) has been used as an alternative to chlorine in water purification to reduce the formation of halogenated by-products and give superior inactivation of microorganisms. However, the formation of chlorite (ClO 2 − ) is a major consideration in the application of ClO 2 . In order to improve understanding in ClO 2 − formation kinetics and mechanisms, this study investigated the reactions of ClO 2 with 30 model compounds, 10 humic substances and 2 surface waters. ClO 2 − yields were found to be dependent on the distribution of functional groups. ClO 2 oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO 2 − yields >50%, while oxidation of olefins, thiols and benzoquinones had ClO 2 − yields <50%. ClO 2 − yields from humic substances depended on the ClO 2 dose, pH and varied with different reaction intervals, which mirrored the behavior of the model compounds. Phenolic moieties served as dominant fast-reacting precursors (during the first 5 min of disinfection). Aromatic precursors (e.g., non-phenolic lignins or benzoquinones) contributed to ClO 2 − formation over longer reaction time (up to 24 h). The total antioxidant capacity (indication of the amount of electron-donating moieties) determined by the Folin-Ciocalteu method was a good indicator of ClO 2 -reactive precursors in waters, which correlated with the ClO 2 demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO 2 − at equivalent ClO 2 exposure, but the prediction in natural water should be conservative.

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