Chlorite formation during ClO2 oxidation of model compounds having various functional groups and humic substances

Gan, Wenhui, Huang, Sirong, Ge, Yuexian, Bond, Tom, Westerhoff, Paul, Zhai, Jiaxin and Yang, Xin (2019) Chlorite formation during ClO2 oxidation of model compounds having various functional groups and humic substances Water Research, 159. pp. 348-357.

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Abstract

Chlorine dioxide (ClO2) 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 (ClO2−) is a major consideration in the application of ClO2. In order to improve understanding in ClO2− formation kinetics and mechanisms, this study investigated the reactions of ClO2 with 30 model compounds, 10 humic substances and 2 surface waters. ClO2− yields were found to be dependent on the distribution of functional groups. ClO2 oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO2− yields >50%, while oxidation of olefins, thiols and benzoquinones had ClO2− yields <50%. ClO2− yields from humic substances depended on the ClO2 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 ClO2− 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 ClO2-reactive precursors in waters, which correlated with the ClO2 demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO2− at equivalent ClO2 exposure, but the prediction in natural water should be conservative.

Item Type:	Article
Divisions :	Faculty of Engineering and Physical Sciences > Civil and Environmental Engineering
Authors :	Name Email ORCID Gan, Wenhui Huang, Sirong Ge, Yuexian Bond, Tom t.bond@surrey.ac.uk Westerhoff, Paul Zhai, Jiaxin Yang, Xin
Date :	1 August 2019
DOI :	10.1016/j.watres.2019.05.020
Copyright Disclaimer :	© 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords :	Chlorine dioxide (ClO2); Chlorite; Chlorate; Disinfection by-products; Water treatment
Depositing User :	Clive Harris
Date Deposited :	20 May 2019 09:54
Last Modified :	20 May 2019 09:54
URI:	http://epubs.surrey.ac.uk/id/eprint/851863

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