Reducing properties of triplet state organic matter (3DOM*) probed via the transformation from chlorine dioxide to chlorite

Kong, Q.; Pan, Yanheng; Lei, Xin; Zhou, Yangjian; Lei, Yu; Peng, Jianglin; Zhang, Xinran; Yin, Ran; Shang, Chii; Yang, Xin

doi:10.1016/j.watres.2022.119120

Cited by 14 publications

(8 citation statements)

References 55 publications

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“…In order to evaluate the role of aromatic ketones in EfOM, sodium borohydride (NaBH 4 ) was used to reduce the aromatic ketones moieties within EfOM before irradiation tests as described in Text S9. 27,35 Analytical Methods. The two eArGs were quantified using short-amplicon qPCR (209 bps for bla TEM-1 and 216 bps for tet-A, Table S3).…”

Section: Methodsmentioning

confidence: 99%

“…The measurement of triplet-state quantum yield coefficients in NOM/EfOM solutions via the electron transfer reaction was made by using 2,4,6-trimethylphenol (TMP) as the probe compound (details in Text S8). In order to evaluate the role of aromatic ketones in EfOM, sodium borohydride (NaBH 4 ) was used to reduce the aromatic ketones moieties within EfOM before irradiation tests as described in Text S9. , …”

Section: Methodsmentioning

confidence: 99%

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Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes

Peng

Pan

Zhou

et al. 2023

Environ. Sci. Technol.

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Wastewater effluent is a major source of extracellular antibiotic resistance genes (eArGs) in the aquatic environment, a threat to human health and biosecurity. However, little is known about the extent to which organic matter in the wastewater effluent (EfOM) might contribute to photosensitized oxidation of eArGs. Triplet states of EfOM were found to dominate the degradation of eArGs (accounting for up to 85%). Photo-oxidation proceeded mainly via proton-coupled electron transfer reactions. They broke plasmid strands and damaged bases. O 2•− was also involved, and it coupled with the reactions' intermediate radicals of eArGs. The second-order reaction rates of bla TEM-1 and tet-A segments (209−216 bps) with the triplet state of 4-carboxybenzophenone were calculated to be (2.61− 2.75) × 10 8 M −1 s −1 . Besides as photosensitizers, the antioxidant moieties in EfOM also acted as quenchers to revert intermediate radicals back to their original forms, reducing the rate of photodegradation. However, the terrestrial origin natural organic matter was unable to photosensitize because it formed less triplets, especially high-energy triplets, so its inhibitory effects predominated. This study advances our understanding of the role of EfOM in the photo-oxidation of eArGs and the difference between EfOM and terrestrial-origin natural organic matter.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes

Peng

Pan

Zhou

et al. 2023

Environ. Sci. Technol.

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“…Even over the range of commonly applied UV doses of 20 to 300 mJ cm –2 , the presence of DOM and hence 3 DOM* increased free chlorine decay rates (Figure S24). To our best knowledge, it is the first time to find that 3 DOM* exhibits a strong reducing capacity toward HOCl and builds upon the recent work showing similar effects of 3 DOM* on enhancing degradation rates of PMS and chlorine dioxide. , …”

Section: Environmental Implicationsmentioning

confidence: 79%

“…The observed free chlorine decay was attributed to three pathways: (i) DOM consumption (rates similar to dark controls), (ii) direct photolysis from UV 254 irradiation, and (iii) indirect photolysis from reacting with transient species formed in DOM or photosensitizer photosensitization. 12,13,31,32,36,42 The role of HO • and Cl • on chlorine decay was absent as the dosed acetate ion (10 mM) completely quenched them (Figure S3). The selected photosensitizers can barely react with free chlorine in the dark (Figure S4).…”

Section: Chemicalsmentioning

confidence: 99%

“…The only evidence was that the free chlorine decay rate decreased slightly (<20%) with increasing DO (the quencher of 3 DOM*, DOM • – , and e aq – ) from 300 to 1200 μM. ,,, However, the lifetime of 1 DOM* (<0.1 ns) is far less than that of 3 DOM* (2–178 μs). − Whether 1 DOM* or other transient species (e.g., 3 DOM*) played predominant roles in free chlorine decay can hardly be concluded based on the very limited evidence. In fact, 3 DOM* has been reported to reduce peroxymonosulfate (PMS) and chlorine dioxide to generate SO 4 •– and chlorite, respectively. , DOM •– was also observed to reduce hydrogen peroxide to form HO • . Additionally, e aq – and O 2 •– can react with free chlorine at 7.2 × 10 9 and 7.5 × 10 6 M –1 s –1 , respectively .…”

Section: Introductionmentioning

confidence: 99%

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Photochemical Transformation of Free Chlorine Induced by Triplet State Dissolved Organic Matter

Kong

Pan

et al. 2023

Environ. Sci. Technol.

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Photolysis of free chlorine is an increasingly recognized approach for effectively inactivating microorganisms and eliminating trace organic contaminants. However, the impact of dissolved organic matter (DOM), which is ubiquitous in engineered water systems, on free chlorine photolysis is not yet well understood. In this study, triplet state DOM ( 3 DOM*) was found to cause the decay of free chlorine for the first time. By using laser flash photolysis, the scavenging rate constants of triplet state model photosensitizers by free chlorine at pH 7.0 were determined to be in the range of (0.26−3.33) × 10 9 M −1 s −1 . 3 DOM*, acting as a reductant, reacted with free chlorine at an estimated reaction rate constant of 1.22(±0.22) × 10 9 M −1 s −1 at pH 7.0. This study revealed an overlooked pathway of free chlorine decay during UV irradiation in the presence of DOM. Besides the DOM's light screening ability and scavenging of radicals or free chlorine, 3 DOM* played an important role in the decay of free chlorine. This reaction pathway accounted for a significant proportion of the decay of free chlorine, ranging from 23 to 45%, even when DOM concentrations were below 3 mg C L −1 and a free chlorine dose of 70 μM was present during UV irradiation at 254 nm. The generation of HO • and Cl • from the oxidation of 3 DOM* by free chlorine was confirmed by electron paramagnetic resonance and quantified by chemical probes. By inputting the newly observed pathway in the kinetics model, the decay of free chlorine in UV 254 -irradiated DOM solution can be well predicted.

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Inorganic Disinfection By-Products (DBPs)

Kong,

Fan,

Guan

et al. 2024

The Handbook of Environmental Chemistry

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Reducing properties of triplet state organic matter (3DOM*) probed via the transformation from chlorine dioxide to chlorite

Cited by 14 publications

References 55 publications

Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes

Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes

Photochemical Transformation of Free Chlorine Induced by Triplet State Dissolved Organic Matter

Inorganic Disinfection By-Products (DBPs)

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