Simulated solar light driven Fe(III)/Fe(II) redox cycle for roxarsone degradation and simultaneous arsenate immobilization

Chen, Na; Wang, Xiaobing; Wan, Yichao; Luo, Yani; Huang, Yunhua; Zhang, Lizhi

doi:10.1016/j.jhazmat.2019.121635

Cited by 33 publications

(7 citation statements)

References 44 publications

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“…). 65,66 Figure 2a shows that the addition of 25 mM ethanol and TBA completely inhibited Tl(I) oxidation in both systems, confirming that • OH is the main reactive radical accounting for Tl(I) oxidation. The addition of 30 U/mL SOD suppressed 30.6% and 12.5% of the Tl(I) oxidation rate in the UV and H 2 O 2 systems, respectively, implying a more important role of O 2…”

Section: •−mentioning

confidence: 69%

“…The results suggest that • OH and O 2 •– were both involved in Tl(I) oxidation in Fe(III) solutions when mediated by UV light and H 2 O 2 . The individual roles of these two radicals were further explored through a series of trapping experiments by adding different scavengers (TBA for • OH, ethanol for both Fe(IV) and • OH, and SOD for O 2 •– ). , Figure a shows that the addition of 25 mM ethanol and TBA completely inhibited Tl(I) oxidation in both systems, confirming that • OH is the main reactive radical accounting for Tl(I) oxidation. The addition of 30 U/mL SOD suppressed 30.6% and 12.5% of the Tl(I) oxidation rate in the UV and H 2 O 2 systems, respectively, implying a more important role of O 2 •– in the UV system, which is consistent with the stronger DMPO-O 2 •– signal recorded in the irradiated solutions.…”

Section: Resultsmentioning

confidence: 87%

“…• OH generation at pH < 2.5 and pH > 2.5, respectively. 64,66 The higher photoactivity of Fe(OH) 2+ (approximately 3 times the • OH quantum yield) compared to Fe(H 2 O) 6 3+ could explain the increased k obs values at pH 1.0−3.0. 64 When the solution pH further increased to 4.0−6.0; however, the hydrolytic polymers with a poor photoactivity formed, resulting in less efficient • OH generation and thereby a decreased Tl(I) oxidation rate.…”

Section: •−mentioning

confidence: 99%

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Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Huang

Huangfu

et al. 2022

Environ. Sci. Technol.

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The redox transformation between the oxidation states of thallium (Tl(I) and Tl(III)) is the key to influencing its toxicity, reactivity, and mobility. Dissolved iron (Fe) is widely distributed in the environment and coexists at a high level with Tl in acidic mine drainages (AMDs). While ultraviolet (UV) light and H 2 O 2 can directly (by inducing Tl(III) reduction) and indirectly (by inducing Fe(III) to form reactive intermediates) impact the redox cycles of Tl in Fe(III)-containing solutions, the kinetics and mechanism remain largely unclear. This study is the first to investigate the UV light-and H 2 O 2 -mediated Tl redox kinetics in acidic Fe(III) solutions. The results demonstrate that UV light and H 2 O 2 could directly reduce Tl(III) to Tl(I), with the extent of reduction dependent on the presence of Fe(III) and the solution pH. At pH 3.0, Tl(I) was completely oxidized to Tl(III), which can be ascribed to the generation of hydroxyl radicals ( • OH) from the Fe(III) photoreduction or Fe(III) reaction with H 2 O 2 . The kinetics of Tl(I) oxidation were strongly affected by the Fe(III) concentration, pH, light source, and water matrix. Kinetic models incorporating Tl redox kinetics with Fe redox kinetics were developed and satisfactorily interpreted Tl(III) reduction and Tl(I) oxidation under the examined conditions. These findings emphasize the roles of the UV light-and H 2 O 2 -driven Fe cycles in influencing the redox state of Tl, with implications for determining its mobility and fate in the environment.

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Section: •−mentioning

confidence: 69%

Section: Resultsmentioning

confidence: 87%

Section: •−mentioning

confidence: 99%

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Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Huang

Huangfu

et al. 2022

Environ. Sci. Technol.

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“…Like most organic pollutants, phenylarsenic feed additives can be degraded by a range of oxidation-based technologies, but their breakdown releases the more toxic and mobile inorganic arsenic species. ,,− Thus, the treatment of these organoarsenicals poses unique challenges, and effective capture of the toxic degradation products is as important, if not more important, than degradation of the parent compounds. Recently, treatment schemes based on oxidative degradation of ROX and p -ASA to arsenate followed by sorptive removal of arsenate using the in situ generated or externally added iron (hydro)oxides through Fenton, Fenton-like, ferrate oxidation, and photocatalytic oxidation have been developed, but these methods suffer the general limitations of high cost and tedious operation. ,− In particular, the presence of dissolved organic matter (DOM) at high levels in the manure leachate poses a significant challenge for the above-mentioned treatment technologies through competing for the adsorption sites and competitive scavenging of the oxidants. ,− As a result, alternative technologies that have high efficiency, simple operation, and resistance against the impact of the water matrix components should be explored for treating phenylarsenic feed additives in manure leachate.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Roxarsone Coupled with Sorptive Removal of the Inorganic Arsenic Released by Iron–Carbon (Fe–C) Microelectrolysis

Xie

Cheng

2021

ACS EST Eng.

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Iron–carbon (Fe–C) microelectrolysis was proposed as a novel method for simultaneous degradation of a model phenylarsenic compound, roxarsone (ROX), in manure leachate and removal of the inorganic arsenic released. The initial rate equation for ROX degradation was determined as r init = 1.55[ROX]1.0[Fe–C]0.9[H+]0.5 (μM/min), at the initial solution pH of 2.0–5.0 and in the presence of overdosed Fe–C filler. A unique advantage of Fe–C microelectrolysis process is that ROX was first reduced to 3-amino-4-hydroxyphenylarsenic acid by the atomic hydrogen generated by cathodic reduction under acidic conditions, which facilitated subsequent oxidative attack by HO•. The iron (hydro)oxide precipitate formed from iron corrosion effectively captured the inorganic arsenic released, reducing the residual arsenic level in the treated water and swine manure leachate to <100 μg/L (standard for irrigation water in China), while the treatment performance was barely affected by the major constitutes of water matrix. The residual level of arsenic in the effluent of a Fe–C microelectrolysis column could be kept consistently below 100 μg/L for 5 months with proper replenishment of the Fe–C filler. The concurrent occurrence of reduction and oxidation reactions and the in situ generation of iron (hydro)oxides make Fe–C microelectrolysis process particularly efficient for treating nitroaromatic compounds and organoarsenicals.

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“…ROX could be photodegraded in the aquatic environment, such as in poultry litter leachates and surface water (Chen et al, 2020;Mangalgiri et al, 2015), but ROX photodegradation behavior has not been fully understood. In general, the photodegradation of organic contaminants can be divided into two main types: direct photolysis and indirect photolysis.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of roxarsone in the aquatic environment: influencing factors, mechanisms, and artificial neural network modeling

Meng

Arong

Yuan

et al. 2021

Environ Sci Pollut Res

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Roxarsone (ROX) is an organoarsenic feed additive, and can be discharged into aquatic environment.ROX can photodegrade into more toxic inorganic arsenics, causing arsenic pollution. However, the photodegradation behavior of ROX in aquatic environment is still unclear. To better understand ROX photodegradation behavior, this study investigated the ROX photodegradation mechanism and in uencing factors, and modeled the photodegradation process. The results showed that ROX in the aquatic environment was degraded to inorganic As(III) and As(V) under light irradiation. The degradation e ciency was enhanced by 25 % with the increase of light intensity from 300 µW/cm 2 to 800 µW/cm 2 via indirect photolysis. The photodegradation was temperature dependence, but was only slightly affected by pH. Nitrate ion (NO 3 − ) had an obvious in uence, but sulfate, carbonate, and chlorate ions had a negligible effect on ROX degradation. Dissolved organic matter (DOM) in the solution inhibited the photodegradation. ROX photodegradation was mainly mediated by reactive oxygen species (in the form of single oxygen 1 O 2 ) generated through ROX self-sensitization under irradiation. Based on the data of factors affecting ROX photodegradation, ROX photodegradation model was built and trained by an arti cial neural network (ANN), and the predicted degradation rate was in good agreement with the real values with a root mean square error of 1.008. This study improved the understanding of ROX photodegradation behavior and provided a basis for controlling the pollution from ROX photodegradation.

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Simulated solar light driven Fe(III)/Fe(II) redox cycle for roxarsone degradation and simultaneous arsenate immobilization

Cited by 33 publications

References 44 publications

Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Oxidation of Roxarsone Coupled with Sorptive Removal of the Inorganic Arsenic Released by Iron–Carbon (Fe–C) Microelectrolysis

Photodegradation of roxarsone in the aquatic environment: influencing factors, mechanisms, and artificial neural network modeling

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Simulated solar light driven Fe(III)/Fe(II) redox cycle for roxarsone degradation and simultaneous arsenate immobilization

Cited by 33 publications

References 44 publications

Light- and H2O2-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Light- and H2O2-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Oxidation of Roxarsone Coupled with Sorptive Removal of the Inorganic Arsenic Released by Iron–Carbon (Fe–C) Microelectrolysis

Photodegradation of roxarsone in the aquatic environment: influencing factors, mechanisms, and artificial neural network modeling

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Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights

Light- and H₂O₂-Mediated Redox Transformation of Thallium in Acidic Solutions Containing Iron: Kinetics and Mechanistic Insights