Fast coupling and detoxification of aqueous halobenzoquinones by extracellular nucleophiles: The relationship among structures, pathways and toxicity

Zhong, Chen; Zhao, He; Cao, Hongbin; Huang, Ching-Hua

doi:10.1016/j.cej.2022.135525

Cited by 5 publications

(5 citation statements)

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“…Changes in pH, 61 hydrogen bonds, continuum solvation, 62 as well as the presence of divalent metal cations 33 may lead to g-tensor shifting. Our previous study 55 As shown in Figure 4a, MnO 2 alone would not transform SMX. A major product of SMX with the presence of CAT had molecular ions of m/z 360 and 382 ([M + H] + = 360 and [M + Na] + = 382), which was in accordance with the findings of Guo et al 25 According to the Fukui index (f 0 & f − , Table S1), SMX was more likely to couple to C1 and C2 than other sites.…”

Section: Environmental Science and Technologymentioning

confidence: 69%

“…Changes in pH, 61 hydrogen bonds, continuum solvation, 62 as well as the presence of divalent metal cations 33 may lead to g-tensor shifting. Our previous study 55 S1), SMX was more likely to couple to C1 and C2 than other sites. Hydrolysis occurred in the adducts under elevated temperatures (Figure S10).…”

Section: ■ Introductionmentioning

confidence: 70%

“…Changes in pH, hydrogen bonds, continuum solvation, as well as the presence of divalent metal cations may lead to g -tensor shifting. Our previous study found that Cys would form Michael adducts with chloroquinones. Although Cys completely quenched SQ • , it can still remove SMX over a relatively long time.…”

Section: Resultsmentioning

confidence: 98%

“…Full-oxidation of HQ (RT = 2.37 min) to p-Q (RT = 2.93 min) was observed in our study after 12 min of oxidation by the HPLC method without reductive reagents (Figure S4), indicating that the oxidation of HQ by MnO 2 did not predominate slower removal to SMX. 25 Because reductive reagents not only dissolved MnO 2 but also quenched SQ • and quinone, 55 Role of Dissolved Mn(II)/Mn(III). Conductivity during the reaction was monitored without the presence of background electrolytes or pH buffers for better sensitivity.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

“…Because reductive reagents not only dissolved MnO 2 but also quenched SQ • and quinone,55 all samples were quenched by ultra-…”

mentioning

confidence: 99%

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Degradation of Sulfamethoxazole by Manganese(IV) Oxide in the Presence of Humic Acid: Role of Stabilized Semiquinone Radicals

Zhong,

Cao,

Huang

et al. 2023

Environ. Sci. Technol.

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In this work, we demonstrate for the first time the abatement of sulfamethoxazole (SMX) induced by stabilized orthosemiquinone radicals (o-SQ •− ) in the MnO 2 -mediated system in the presence of humic acid. To evaluate the performance of different MnO 2 /mediator systems, 16 mediators are examined for their effects on MnO 2 reactions with SMX. The key role of the bidentate Mn(II)o-SQ • complex and MnO 2 surface in stabilizing SQ •− is revealed. To illustrate the formation of the Mn(II)-o-SQ • complex, electron spin resonance, cyclic voltammetry, and mass spectra were used. To demonstrate the presence of o-SQ • on the MnO 2 surface, EDTA was used to quench Mn(II)-o-SQ • . The high stability of o-SQ •− on the MnO 2 surface is attributed to the higher potential of o-SQ •− (0.9643 V) than the MnO 2 surface (0.8598 V) at pH 7.0. The SMX removal rate constant by different stabilized o-SQ • at pH 7.0 ranges from 0.0098 to 0.2252 min −1 . The favorable model is the rate constant ln (k obs, 7.0 ) = 6.002E HOMO (o-Q red ) + 33.744(E LUMO (o-Q) − E HOMO (o-Q red )) − 32.800, whose parameters represent the generation and reactivity of o-SQ • , respectively. Moreover, aniline and cystine are competitive substrates for SMX in coupling o-SQ •− . Due to the abundance of humic constituents in aquatic environments, this finding sheds light on the low-oxidant-demand, low-carbon, and highly selective removal of sulfonamide antibiotics.

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