Can the commonly used quenching method really evaluate the role of reactive oxygen species in pollutant abatement during catalytic ozonation?

Guo, Yang; Long, Jingfei; Huang, Jun; Yu, Gang; Wang, Huijiao

doi:10.1016/j.watres.2022.118275

Cited by 204 publications

(68 citation statements)

References 52 publications

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“…Parallel experiments were performed with the addition of 1 mM TBA, p -BQ, and CHCl 3 . According to previous reports, , the second-order reaction rate constants of TBA and p -BQ were 0.6 × 10 9 and 0.1 × 10 9 M –1 s –1 , respectively, which did not display an obvious differences in the order of magnitude. From Figure b, TBA and p -BQ showed similar inhabitation effects of 31.1% and 26.0%, respectively.…”

Section: Resultssupporting

confidence: 60%

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

Zhong

Zhu

Zhou

et al. 2022

ACS Appl. Nano Mater.

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Electrochemical advanced oxidation processes (EAOPs) are a class of promising technologies for wastewater remediation. The challenge of EAOPs is the in situ generation and activation of hydrogen peroxide (H2O2) to evolve reactive oxygen species (ROS) simultaneously with low energy consumption and high performances. In this work, we designed an EAOP system, coupling FeOCl nanoparticles on oxygen-enriched carbon nanotubes (O-CNTs) and a nickel foam (FeOCl/O-CNTs/NF) cathode for electro-Fenton (EF) reactions and an IrO2/Ti anode for anodic oxidation (AO) simultaneously. Specifically, the defects and oxygen functional groups on O-CNTs introduced by a modified Hummers’ method could induce the charge redistribution of O-CNTs for outstanding two-electron oxygen-reduction-reaction performances (H2O2 selectivity of 73%) and provide more anchoring sites for the loading of active cocatalyst nanoparticles. Thus, abundant FeOCl nanoparticles were successfully loaded onto O-CNTs. Such a FeOCl/O-CNTs/NF cathode exhibited a high H2O2 production rate of 95 mmol gcat –1 h–1 because of the improved exposure of catalytic active sites supported on nickel foam to attain a large specific surface area. •OH was generated from H2O2 via both heterogeneous and homogeneous EF processes induced by the FeOCl/O-CNTs/NF cathode and leached ferrous ions accordingly. Sulfamethoxazole (SMX) was completely removed within 30 min at a low specific energy consumption of 0.024 kWh g–1 SMX–1. Thus, the simultaneous FeOCl/O-CNTs/NF-based EF system and AO provide an efficient and cost-effective technology for organic contaminant remediation.

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Section: Resultssupporting

confidence: 60%

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

Zhong

Zhu

Zhou

et al. 2022

ACS Appl. Nano Mater.

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“…With respect to the role of 1 O 2 , the observation that adding 5–50 mM TBA could not fully depress the degradation of FFA at pH 9.0 (Figure b) indicates that 1 O 2 might be produced in the H 2 O 2 /periodate process. To verify this assumption, FFA oxidation was further examined in the presence of L-histidine, which is a scavenger for both 1 O 2 and HO · . , It was found that FFA oxidation was completely quenched upon the addition of l -histidine at pH 9.0 (Figure b), confirming that 1 O 2 played a role in the H 2 O 2 /periodate process. Note that the reactivity and contribution of 1 O 2 toward organic contaminant degradation may be substrate-specific, but the significant scavenging effect of TBA on FFA removal (Figure b) suggested that 1 O 2 was not the major ROS in the H 2 O 2 /periodate process, even at alkaline pH. …”

Section: Resultsmentioning

confidence: 91%

Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H₂O₂/Periodate Process

Chen

Sun

Dong

et al. 2022

Environ. Sci. Technol.

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Although periodate-based advanced oxidation processes have been proven to be efficient in abating organic contaminants, the activation properties of different periodate species remain largely unclear. Herein, by highlighting the role of H4IO6 –, we reinvestigated the pH effect on the decontamination performance of the H2O2/periodate process. Results revealed that elevating pH from 2.0 to 10.0 could markedly accelerate the rates of organic contaminant decay but decrease the amounts of organic contaminant removal. This pH-dependent trend of organic contaminant degradation corresponded well with the HO· yield and the variation of periodate species. Specifically, although 1O2 could be detected at pH 9.0, HO· was determined to be the major reactive oxidizing species in the H2O2/periodate process under all the tested pH levels. Furthermore, it was suggested that only H4IO6 – and H2I2O10 4– could serve as the precursors of HO·. The second-order rate constant for the reaction of H2I2O10 4– species with H2O2 was determined to be ∼1199.5 M–1 s–1 at pH 9.0, which was two orders of magnitude greater than that of H4IO6 – (∼2.2 M–1 s–1 at pH 3.0). Taken together, the reaction pathways of H2O2 with different periodate species were proposed. These fundamental findings could improve our understanding of the periodate-based advanced oxidation processes.

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“…We would like to highlight that if O 2 •– , formed via chain reactions initiated on • OH-mediated oxidation of organics, is directly involved in the oxidation of organics as reported in the case of CCl 4 and CHCl 3 , then addition of TBA will inhibit superoxide-mediated oxidation of these organics and lead to erroneous conclusions. However, direct oxidation of organics via interaction with O 2 •– is unlikely as O 2 •– is expected to react with O 3 rather than the organics, since (i) the rate constant for the O 3 and O 2 •– reaction (1.6 × 10 9 M –1 s –1 ) is much higher than the reported rate constants for O 2 •– reaction with various organics, and (ii) the concentration of O 3 is usually higher than the concentration of organics present.…”

Section: Resultsmentioning

confidence: 92%

Caveats in the Use of Tertiary Butyl Alcohol as a Probe for Hydroxyl Radical Involvement in Conventional Ozonation and Catalytic Ozonation Processes

et al. 2022

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In this study, we enunciate the limitations associated with the use of tert-butanol (TBA) to deduce the contribution of hydroxyl radicals ( • OH) in organic oxidation during conventional ozonation and/or heterogeneous catalytic ozonation (HCO). Our results show that TBA is unable to access surface-located • OH formed during HCO. Furthermore, TBA may also interfere with the adsorption of organic compounds on the catalyst surface and decrease the adsorptive as well as concomitant oxidative removal of organics via nonradical-mediated pathways (if important). Our results also demonstrate that TBA scavenging results are inconclusive for mildly ozone reactive compounds due to switching from O 3 / • OH-mediated oxidation in the absence of TBA to O 3 -driven oxidation in the presence of TBA. The presence of TBA may also decrease the rate of ozone decay with the increased stability of O 3 in the presence of TBA, facilitating (i) direct oxidation of ozone-reactive organics in the bulk solution and/or (ii) diffusion of O 3 to the catalyst surface and subsequent surface-mediated oxidation of organics. Overall, we conclude that caution needs to be exercised when interpreting the observations made in the presence of TBA and also describe the further experimentation required to confirm/reject the role of • OH in organic oxidation. The findings of this work should assist in preventing researchers from reaching erroneous conclusions regarding the involvement of • OH in catalytic or conventional ozonation processes.

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Can the commonly used quenching method really evaluate the role of reactive oxygen species in pollutant abatement during catalytic ozonation?

Cited by 204 publications

References 52 publications

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H₂O₂/Periodate Process

Caveats in the Use of Tertiary Butyl Alcohol as a Probe for Hydroxyl Radical Involvement in Conventional Ozonation and Catalytic Ozonation Processes

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Can the commonly used quenching method really evaluate the role of reactive oxygen species in pollutant abatement during catalytic ozonation?

Cited by 204 publications

References 52 publications

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H2O2/Periodate Process

Caveats in the Use of Tertiary Butyl Alcohol as a Probe for Hydroxyl Radical Involvement in Conventional Ozonation and Catalytic Ozonation Processes

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Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H₂O₂/Periodate Process