Redox Conversion of Arsenite and Nitrate in the UV/Quinone Systems

Chen, Zhihao; Jin, Jiyuan; Song, Xiaojie; Zhang, Guoyang; Zhang, Shujuan

doi:10.1021/acs.est.8b03538

Cited by 47 publications

(25 citation statements)

References 55 publications

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“…In the acidic environment, both phenolic (−OH)- and quinone (CO)-type functionalities activated O 2 to form • HO 2 responsible for H 2 O 2 generation, which produces • OH via a successive single-electron transfer resulting in As(III) oxidation. Single or multiple stages can be contributed toward As(III) to As(V) oxidation via double- or single-electron transfer . The following reaction pathway (eqs –) can be suggested for the present study The DO concentrations in the effluent solutions are not noticeably correlated with the oxygen flow rate and the fluctuation range of DO concentrations in these cases shows a good overlap in general (Table S2).…”

Section: Results and Discussionmentioning

confidence: 88%

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Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Mahandra

Ghahreman

2020

Ind. Eng. Chem. Res.

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This work pertains to a novel continuous column process for As(III) oxidation using commercial activated carbon as a promising catalyst in acidic solutions on a minipilot scale. Notable efficiency of arsenic oxidation is validated in continuous column tests treating 5 g/L As(III) acidic solutions with activated carbon in the presence of oxygen. Residence time, pH, dissolved oxygen, and initial As(III) concentration are proved to be the significant impacting parameters on the arsenic oxidation process. Insights into the oxidation pathway by Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) illustrate that the efficient oxidation of arsenic is attributed to the ample oxygen functionalities on the carbon surfaces, which play a role in the in situ formation of hydrogen peroxide. This study provides a promising process for the application of activated carbon in arsenic oxidation from highly concentrated arsenic waste solutions in the mining and metal industries.

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Section: Results and Discussionmentioning

confidence: 88%

“…Single or multiple stages can be contributed toward As(III) to As(V) oxidation via doubleor single-electron transfer. 44 The following reaction pathway (eqs 4−7) can be suggested for the present study…”

Section: Columnmentioning

confidence: 99%

Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Mahandra

Ghahreman

2020

Ind. Eng. Chem. Res.

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“…To examine the thermodynamic basis of As(III) oxidation, we first calculated their Eh values at different pH values based on standard reduction potential (Eh) and p K a values of As(V)/As(III) (here the occurrence of double-electron transfer reaction is assumed for simplifying the Eh calculation) , and the involved ROS redox couples (i.e., O 2 /•HO 2 couple via R3, H 2 O 2 /H 2 O couple, and •OH/H 2 O couple). − The Eh values of the As(V)/As(III) couple were calculated to be 0.239 V at pH 3.0, −0.122 V at pH 7.0, and −0.397 V at pH 9.5 (Figure S16). In comparison, the Eh values of the O 2 /•HO 2 couple were −0.021 V at pH 3.0 and −0.127 V at pH 7.0, lower than or close to those of the As(V)/As(III) couple at these two pH values.…”

Section: Resultsmentioning

confidence: 99%

pH Dependence of Arsenic Oxidation by Rice-Husk-Derived Biochar: Roles of Redox-Active Moieties

Zhong

Jiang

Zhao

et al. 2019

Environ. Sci. Technol.

213

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Biochars have demonstrated great potential for water decontamination and soil remediation; however, their redox reactivity toward trace contaminants and the corresponding redox-active moieties (RAMs, i.e., phenolic −OH, semiquinone-type persistent free radicals (PFRs), and quinoid CO) remain poorly understood. Here we investigated the roles of the RAMs on biochar in oxidation of As(III) under varying pH and O2 conditions. The results showed that the promoted oxidation of As(III) by the RAMs is strongly pH dependent. Under acidic and neutral conditions, only the oxidation of As(III) by •OH and H2O2 produced from activation of O2 by phenolic −OH and semiquinone-type PFRs occurred. In contrast, the oxidation by semiquinone-type PFRs, quinoid CO, and H2O2 (if O2 was introduced) appeared under alkaline conditions. This pH-dependent oxidation behavior was attributed to the varying redox activities of RAMs, as confirmed by multiple characterization and validation experiments using biochar with tuned RAMs compositions, as well as thermodynamics evaluation. Our findings provide new insights into the roles of the RAMs on biochar in the promoted oxidation of trace As(III) over a broader pH range under both anoxic and oxic conditions. This study also paves a promising way to oxidize As(III) with biochar.

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“…The diffuse reflectance UV–visible absorption spectra (DR-UVS) were measured by a UV-2600 PRO (Shimadzu, Japan) coupled with an integrating sphere . The aqueous concentrations of As(III) and As(V) were determined with a combined high-performance liquid chromatograph–atomic fluorescence spectrometer (HPLC-AFS, AF-640A, Rayleigh, Beijing, China) . Hydrogen peroxide was quantified with a potassium titanyl oxalate spectrophotometric method at 400 nm …”

Section: Materials and Methodsmentioning

confidence: 99%

“…24 The aqueous concentrations of As(III) and As(V) were determined with a combined high-performance liquid chromatograph−atomic fluorescence spectrometer (HPLC-AFS, AF-640A, Rayleigh, Beijing, China). 25 Hydrogen peroxide was quantified with a potassium titanyl oxalate spectrophotometric method at 400 nm. 26 DFT Calculations.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Enhanced Fenton-like Oxidation of As(III) over Ce–Ti Binary Oxide: A New Strategy to Tune Catalytic Activity via Balancing Bimolecular Adsorption Energies

Shan

Liu

Hua

et al. 2020

Environ. Sci. Technol.

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The development of catalysts for oxidation of aqueous contaminants has long been relying on trial-and-error strategies due to lack of activity-tuning principles. Herein, Fenton-like oxidation of As(III) as a chemisorbed model contaminant over a series of fabricated Ce x Ti1‑x O2 catalysts with tunable structures was investigated. The activity of Ce x Ti1–x O2 showed a volcano-shape dependency on Ce molar fraction, peaking at Ce0.25Ti0.75O2 (x = 0.25) with 6.32–6.36 times higher activity and 2.67–2.94 times higher specific activity compared with CeO2 and TiO2. The non-radical surface hydroperoxo complexes were experimentally substantiated as the dominant oxidant species on Ce0.25Ti0.75O2, which enabled a high efficiency of H2O2 utilization (99.1%). Under the verified Langmuir–Hinshelwood mechanism, the microkinetic model for the catalytic oxidation was established, and thus, the quantitative relationship between activity and adsorption energies for bimolecular chemisorption reactions was elucidated. Theoretically, a catalyst with identical adsorption energies toward both chemisorbed reactants tends to obtain the highest activity. Through DFT calculation, the highest activity of Ce0.25Ti0.75O2 was rationally interpreted by the balanced adsorption energies toward As(III) and H2O2, which was attributed to the shifted electronic density of states induced by Ce doping. This study provides a potent strategy to tune the catalytic activity of bimolecular chemisorption reactions.

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Redox Conversion of Arsenite and Nitrate in the UV/Quinone Systems

Cited by 47 publications

References 55 publications

Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

pH Dependence of Arsenic Oxidation by Rice-Husk-Derived Biochar: Roles of Redox-Active Moieties

Enhanced Fenton-like Oxidation of As(III) over Ce–Ti Binary Oxide: A New Strategy to Tune Catalytic Activity via Balancing Bimolecular Adsorption Energies

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