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Chlorination of isothiazolinone biocides: kinetics, reactive species, pathway, and toxicity evolution.
Wang, Wen-Long; Nong, Yu-Jia; Yang, Zheng-Wei; Wu, Qian-Yuan; Hübner, Uwe.
  • Wang WL; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua Un
  • Nong YJ; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua Un
  • Yang ZW; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua Un
  • Wu QY; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua Un
  • Hübner U; Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, Garching 85748, Germany. Electronic address: u.huebner@tum.de.
Water Res ; 223: 119021, 2022 Sep 01.
Article in English | MEDLINE | ID: covidwho-2004603
ABSTRACT
Due to the Covid-19 pandemic, the worldwide biocides application has been increased, which will eventually result in enhanced residuals in treated wastewater. At the same time, chlorine disinfection of secondary effluents and hospital wastewaters has been intensified. With respect to predicted elevated exposure in wastewater, the chlorination kinetics, transformation pathways and toxicity evolution were investigated in this study for two typical isothiazolinone biocides, methyl-isothiazolinone (MIT) and chloro-methyl-isothiazolinone (CMIT). Second-order rate constants of 0.13 M-1·s-1, 1.95 × 105 M-1·s-1 and 5.14 × 105 M-1·s-1 were determined for the reaction of MIT with HOCl, Cl2O and Cl2, respectively, while reactivity of CMIT was around 1-2 orders of magnitude lower. While chlorination of isothiazolinone biocides at pH 7.1 was dominated by Cl2O-oxidation, acidic pH and elevated Cl- concentration favored free active chlorine (FAC) speciation into Cl2 and increased overall isothiazolinone removal. Regardless of the dominant FAC species, the elimination of MIT and CMIT resulted in an immediate loss of acute toxicity under all experimental conditions, which was attributed to a preferential attack at the S-atom resulting in subsequent formation of sulfoxides and sulfones and eventually an S-elimination. However, chlorination of isothiazolinone biocides in secondary effluent only achieved <10% elimination at typical disinfection chlorine exposure 200 mg·L-1·min, but was predicted to be remarkably increased by acidizing solution to pH 5.5. Alternative measures might be needed to minimize the discharge of these toxic chemicals into the aquatic environment.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Water Pollutants, Chemical / Water Purification / Disinfectants / COVID-19 Type of study: Prognostic study Limits: Humans Language: English Journal: Water Res Year: 2022 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Water Pollutants, Chemical / Water Purification / Disinfectants / COVID-19 Type of study: Prognostic study Limits: Humans Language: English Journal: Water Res Year: 2022 Document Type: Article