UV-induced reactive species dynamics and product formation by chlorite.

Autor: Zhao R; Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK; Water Innovation and Research Centre, University of Bath, BA2 7AY, UK., Chew YMJ; Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK., Hofman JAMH; Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK; Water Innovation and Research Centre, University of Bath, BA2 7AY, UK., Lutze HV; Civil- and Environmental Engineering, Institute IWAR, Technical University of Darmstadt, 64287 Darmstadt, Germany; IWW Water Centre, Moritzstrasse 26, 45476, Mülheim an der Ruhr, Germany; Centre for Water and Environmental Research (ZWU), Universitätsstrasse 5, 45141, Essen, Germany. Electronic address: H.Lutze@iwar.tu-darmstadt.de., Wenk J; Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK; Water Innovation and Research Centre, University of Bath, BA2 7AY, UK. Electronic address: j.h.wenk@bath.ac.uk.
Jazyk: angličtina
Zdroj: Water research [Water Res] 2024 Oct 15; Vol. 264, pp. 122218. Date of Electronic Publication: 2024 Aug 04.
DOI: 10.1016/j.watres.2024.122218
Abstrakt: Chlorite (ClO 2 - ) is a regulated byproduct of chlorine dioxide water treatment processes. The transformation of chlorite under UV irradiation into chloride (Cl - ) and chlorate (ClO 3 - ) involves reactive species chain reactions that could enhance chlorine dioxide water treatment efficiency while reducing residual chlorite levels. This study conducted a mechanistic investigation of chlorite phototransformation by analyzing reaction intermediates and stable end products, including chlorine dioxide (ClO 2 ), free chlorine (HOCl/OCl - ), hydroxyl‑radical ( • OH), Cl - , and ClO 3 - through combined experimental and modeling approaches. Experiments were performed at UV 254 irradiation in pure buffered water within the pH range of 6 to 8. Results indicated that the apparent quantum yields for chlorite phototransformation increased from 0.86 to 1.45, and steady-state • OH concentrations at 1 mM initial chlorite concentration rose from 8.16 × 10 -14 M - 16.1 × 10 -14 M with decreasing pH values. It was observed that under UV irradiation, chlorite acts as both a significant producer and consumer of reactive species through three distinct reaction pathways. The developed kinetic model, which incorporates optimized intrinsic chlorite quantum yields Φ chlorite in ranging from 0.33 to 0.39, effectively simulated the loss of oxidants and the formation of major products. It also accurately predicted steady-state concentrations of various species, including • OH, • ClO, Cl • and O 3 . For the first time, this study provides a comprehensive transformation pathway scheme for chlorite phototransformation. The findings offer important insights into the mechanistic aspects of product and oxidizing species formation during chlorite phototransformation.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
Databáze: MEDLINE
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