Hydroxyl radicals in anodic oxidation systems: generation, identification and quantification

Xie, Jiangzhou; Zhang, Changyong; Waite, T. David

doi:10.1016/j.watres.2022.118425

Cited by 123 publications

(43 citation statements)

References 171 publications

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“…The signals of singlet oxygen ( 1 O 2 ) were also observed in electrolysis ( E ), E/PDS, and E/PDS/CNT systems (Figure S4b). Alcohols such as tert -butyl alcohol (TBA) and methanol (MeOH) are used as quenchers for radicals in the bulk solution or on the catalyst surface. − Despite this, KI is an effective scavenger of SBRs, , KI would react with persulfate ions as a reducing agent, and thus cannot be directly used in persulfate systems . As shown in Figure S5, radical quenchers, that is, methanol (MeOH) and TBA, as well as the singlet oxygen scavenger (TEMP) had a trivial impact on DCP degradation in either E/PDS/CNT or PDS/CNT systems, implying that radicals and singlet oxygen were not the primary ROS for DCP degradation.…”

Section: Resultsmentioning

confidence: 99%

Electro-Induced Carbon Nanotube Discrete Electrodes for Sustainable Persulfate Activation

Ren

Zhang

Cheng

et al. 2022

Environ. Sci. Technol.

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In electrochemical advanced oxidation processes (EAOPs), the rate-limiting step is the mass transfer of pollutants to the electrodes due to the limited active surface areas. To this end, we established a three-dimensional (3D) EAOP system by coupling conventional graphite electrodes with dispersed carbon nanotubes (CNTs). The electrodes (particularly the anode) induced electric field spontaneously polarized CNTs into dispersed reactive particle electrodes (CNT-PEs) in the solution, which remarkably promoted electrochemical activation of peroxydisulfate (PDS) to generate surface CNT–PDS* complexes and surface-bound radicals (SBRs). Based on the excited potential (E CNT‑PEs) at different positions in the 3D electric field, CNT-PEs were activated into three states. (i) E CNT‑PEs < E organic, CNT-PEs are chemically inert toward DCP oxidation; (ii) E organic < E CNT‑PEs < E water, CNT-PEs will oxidize DCP via an electron-transfer process (ETP); (iii) E CNT‑PEs > E water, both CNT–PDS* complexes and the anode will oxidize water to produce SBRs. Thus, DCP could be oxidized by CNT–PDS* complexes via ETP to form polychlorophenols on the CNT surface, causing rapid deactivation of the micro-electrodes. In contrast, SBRs attack DCP directly into chloride ions and hydroxylated products, maintaining the surface cleanliness and activity of CNT-PEs for long-term operations.

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Section: Resultsmentioning

confidence: 99%

Electro-Induced Carbon Nanotube Discrete Electrodes for Sustainable Persulfate Activation

Ren

Zhang

Cheng

et al. 2022

Environ. Sci. Technol.

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“…In correlational study, the Oxidation reduction potential (ORP) of slightly acidic electrolyzed water is improved within 400 mv than tap water, as shown in Fig. 1d, the strong oxidation of HR raised the ORP by more than 500 mv, which can significantly affect the anti-microbial capacity of HRW (Xie et al, 2022;Zhang, C et al, 2019).…”

Section: Properties Of Hrw In Treatmentmentioning

confidence: 91%

“…Hydroxyl radical (HR) can decompose organic pollutants with strong oxidation, using REDOX or free radical chain reaction for sterilization and disinfection (Xie et al, 2022). The REDOX potential of HR is higher than that of general strong oxidants, as shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

“…This approach is efficient, however, it might make plant cells a potential target for attack, resulting in the loss of functional components or aromatic substances. Recently, HR has been widely used in environmental fields for wastewater treatment, microbial control, etc., exhibiting good organic contaminant degradation and microbial removal effects (Xie et al, 2022;Vatansever et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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Effect of hydroxyl radical water treatment on functional components, volatile compounds and preservation of four different fruits and vegetables

Huang

Wang

Cheng

et al. 2022

Preprint

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Hydroxyl radical has been widely applied in the non-food fields, but whether its feasibility for treating fruits and vegetables remains unknown. In this work, effects of hydroxyl radical water (HRW) treatment on functional components, volatile compounds, and preservation properties of cherry tomato, grape, coriander and celery were investigated. Results showed that HRW treatment could be significantly effective on delaying the color change and decay of fruits and vegetables. Besides causing a slim loss of total sugars, HRW-treated samples exhibited different losses of total phenols and ascorbic acid. The total phenol and ascorbic acid of celery were lost by 17.95% and 13.01% respectively, which may be caused by excessive surface area, indicating that the applicability of HRW to celery is still to be discussed. The loss of functional components of both fruits could be controlled under 4%. Phenolic profiles and volatile compounds kept almost steadily during treatment. Notably, the increased contents of partial ester compounds might improve the sensory of fruits and vegetables, cherry tomatoes treated with HRW showed an increase of 77.28% in ethyl caproate. Moreover, the reduction of some compounds obtained from the decomposition of fatty acid hydroperoxides may enhance the fresh odor of fruits and vegetables. Accordingly, HRW treatment is a safety and environmental technology for post-harvest processing of fruits and vegetables.

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“…The change in the absorbance value, that is, the hydroxyl radical content, before and after the reaction was detected by dyeing with a dye, and compared. The number of free radicals in the system was determined through spectrophotometry after being dyed with salicylic acid [ 29 ], methylene blue [ 30 ], and crystal violet [ 31 ] and standing for 20 min. The absorbance of salicylic acid was measured at 660 nm, and that of methylene blue and crystal violet was measured at 530 nm.…”

Section: Methodsmentioning

confidence: 99%

Bactericidal Effect and Associated Properties of Non-Electrolytic Hypochlorite Water on Foodborne Pathogenic Bacteria

Gao

Liu

et al. 2022

Foods

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This study investigated the broad-spectrum bactericidal activity of non-electrolytic hypochlorite water (NEHW) and detected its hydroxyl radical content compared with that of slightly acidic electrolytic water (SAEW). Based on the results of UV scanning and storage stability, higher hypochlorite content and stronger oxidation were found to be responsible for the stronger bactericidal effect of NEHW. NEHW can achieve 99% bacterial disinfection effect by treating with 10 mg/L available chlorine concentration for more than 5 minutes. At the same time, the storage stability of NEHW was higher than that of SAEW. After 20 days of storage under sealed and dark conditions, the pH value only increased by 7.9%, and the effective chlorine concentration remained nearly 80%. The results showed that NEHW had higher germicidal efficacy and storage stability than SAEW.

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Hydroxyl radicals in anodic oxidation systems: generation, identification and quantification

Cited by 123 publications

References 171 publications

Electro-Induced Carbon Nanotube Discrete Electrodes for Sustainable Persulfate Activation

Electro-Induced Carbon Nanotube Discrete Electrodes for Sustainable Persulfate Activation

Effect of hydroxyl radical water treatment on functional components, volatile compounds and preservation of four different fruits and vegetables

Bactericidal Effect and Associated Properties of Non-Electrolytic Hypochlorite Water on Foodborne Pathogenic Bacteria

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