Aqueous Iron(IV)–Oxo Complex: An Emerging Powerful Reactive Oxidant Formed by Iron(II)-Based Advanced Oxidation Processes for Oxidative Water Treatment

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(3), P. 1492 - 1509

Published: Jan. 10, 2022

High-valent iron(IV)–oxo complexes are of great significance as reactive intermediates implicated in diverse chemical and biological systems. The aqueous complex (FeaqIVO2+) is the simplest but one most powerful ferryl ion species, which possesses a high-spin state, high reduction potential, long lifetime. It has been well documented that FeaqIVO2+ reacts with organic compounds through various pathways (hydrogen-atom, hydride, oxygen-atom, electron transfer electrophilic addition) at moderate reaction rates show selective reactivity toward inorganic ions prevailing natural water, single out superior candidate for oxidative water treatment. This review provides state-of-the-art knowledge on properties oxidation mechanism kinetics FeaqIVO2+, special attention to similarities differences two representative free radicals (hydroxyl radical sulfate radical). Moreover, prospective role Feaq2+ activation-initiated advanced processes (AOPs) intensively investigated over past 20 years, significantly challenged conventional recognition dominated these AOPs. latest progress identifying contribution Feaq2+-based AOPs thereby reviewed, highlighting controversies nature oxidants formed several activated peroxide oxyacid processes. Finally, future perspectives advancing evaluation from an engineering viewpoint proposed.

Language: Английский

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Ozone chemistry in western U.S. wildfire plumes

Science Advances, Journal Year: 2021, Volume and Issue: 7(50)

Published: Dec. 8, 2021

Wildfires are a substantial but poorly quantified source of tropospheric ozone (O3). Here, to investigate the highly variable O3 chemistry in wildfire plumes, we exploit situ chemical characterization western wildfires during FIREX-AQ flight campaign and show that production can be predicted as function experimentally constrained OH exposure, volatile organic compound (VOC) reactivity, fate peroxy radicals. The exhibits rapid transition regimes. Within few daylight hours, formation substantially slows is largely limited by abundance nitrogen oxides (NOx). This finding supports previous observations enhanced when VOC-rich smoke mixes into NOx-rich urban thereby deteriorating air quality. Last, relate underlying fire characteristics, enabling more accurate representation atmospheric models used study quality predict climate.

Language: Английский

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Expediting Toluene Combustion by Harmonizing the Ce–O Strength over Co-Doped CeZr Oxide Catalysts

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(4), P. 1797 - 1806

Published: Jan. 13, 2023

Low-temperature catalytic degradation of volatile organic compounds (VOCs) by enhancing the activity non-precious metal catalysts has always been focus attention. The mineralization aromatic VOCs requires participation a large number oxygen atoms, so activation species is crucial in reaction. Herein, we originally adjust Ce-O bond strength CeZr oxide cobalt doping to promote species, thus improving toluene performance while maintaining high stability. Subsequent characterizations and theoretical calculations demonstrate that weakening increases vacancy content, promotes enhances redox ability catalysts. This strategy also accelerates depletion intermediate species. study will contribute enhance non-noble catalysts, thereby VOCs.

Language: Английский

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Organic Peroxides in Aerosol: Key Reactive Intermediates for Multiphase Processes in the Atmosphere

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(4), P. 1635 - 1679

Published: Jan. 11, 2023

Organic peroxides (POs) are organic molecules with one or more peroxide (−O–O−) functional groups. POs commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve temporary reservoirs for oxidative radicals (HOx ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, reactivity, key reactive intermediates atmospheric multiphase processes determining life cycle (formation, growth, aging), climate, health impacts of aerosol. However, there remain substantial gaps origin, molecular diversity, fate due complex nature dynamic behavior. Here, we summarize current understanding on POs, a focus identification quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, chemical transformation pathways, well environmental impacts. We find that interactions SO2 transition metal ions generally fast PO pathways liquid water, lifetimes estimated be minutes hours, while hydrolysis is particularly important α-substituted hydroperoxides. Meanwhile, photolysis thermolysis likely minor sinks POs. These distinctly different fates, such reaction OH radicals, which highlights need understand By summarizing advances remaining challenges investigation propose future research priorities regarding fate,

Language: Английский

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Low-Temperature Combustion of Toluene over Cu-Doped SmMn₂O₅ Mullite Catalysts via Creating Highly Active Cu²⁺–O–Mn⁴⁺ Sites

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(14), P. 10433 - 10441

Published: June 25, 2022

Catalytic combustion of volatile organic compounds (VOCs) at low temperatures is still an urgent issue to be solved. Herein, low-temperature toluene over Cu-doped SmMn2O5 mullite catalysts via creating highly active Cu2+-O-Mn4+ sites has been originally demonstrated. exhibited 90% conversion 206 °C and displayed robust stability even in the presence water. It demonstrated that Cu doping created composite were more exposed after removing surface Sm species acid-etching. Benefiting from this, redox oxygen activation ability was significantly enhanced. The consumption benzaldehyde benzoic acid as intermediate CO2 generation apparently promoted, which direct reasons for enhanced toluene. This work provides novel ideas development high-performance VOC combustion, great industrial application prospects.

Language: Английский

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Oxidation Flow Reactor Results in a Chinese Megacity Emphasize the Important Contribution of S/IVOCs to Ambient SOA Formation

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 56(11), P. 6880 - 6893

Published: Dec. 13, 2021

Oxygenated volatile organic compounds (OVOCs) and secondary aerosol (SOA) formation potential of ambient air in Guangzhou, China was investigated using a field-deployed oxidation flow reactor (OFR). The OFR used to mimic hours weeks atmospheric exposure hydroxyl (OH) radicals within the 2–3 min residence time. A comprehensive investigation on variation VOCs OVOCs as function OH is shown. Substantial acids nitrogen-containing OVOC species were observed. Maximum SOA observed following 1–4 equiv days' exposure. produced from known/measured VOC/IVOC precursors such single-ring aromatics long-chain alkanes can account for 52–75% measured under low NOx 26–60% high conditions based laboratory yield parametrizations. To our knowledge, this first time that contribution (8–20%) (C8–C20) alkane quantified direct measurement. By additionally estimating unmeasured semivolatile intermediate volatility (S/IVOCs) are committed with C8–C20 alkanes, 64–100% be explained, signifying important S/IVOCs large cyclic SOA.

Language: Английский

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Seasonal variation in oxygenated organic molecules in urban Beijing and their contribution to secondary organic aerosol

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(15), P. 10077 - 10097

Published: Aug. 5, 2022

Abstract. Oxygenated organic molecules (OOMs) are crucial for atmospheric new particle formation and secondary aerosol (SOA) growth. Therefore, understanding their chemical composition, temporal behavior, sources is of great importance. Previous studies on OOMs mainly focus environments where biogenic predominant, yet sites with dominant anthropogenic emissions, such as megacities, have been lacking. Here, we conducted long-term measurements OOMs, covering four seasons the year 2019, in urban Beijing. The OOM concentration was found to be highest summer (1.6×108 cm−3), followed by autumn (7.9×107 spring (5.7×107 cm−3) winter (2.3×107 suggesting that enhanced photo-oxidation together rise temperature promote OOMs. Most contained 5 10 carbon atoms 3 7 effective oxygen (nOeff=nO-2×nN). average nOeff increased increasing capacity, which lowest autumn. By performing a newly developed workflow, were classified into following types: aromatic aliphatic isoprene monoterpene Among them, (29 %–41 %) (26 main contributors all seasons, indicating Beijing dominated sources. contribution significantly (33 %), much higher than those other three (8 %–10 %). Concentrations (0.2–5.3×107 (1.1–8.4×106 lower reported at sites, they possessed nitrogen contents due high NOx levels (9.5–38.3 ppbv – parts per billion volume) With regard content two composed CHO CHON species, while CHON2 ones. Such prominent differences suggest varying pathways between these combining an dynamic model, estimated SOA growth rate through condensation could reach 0.64, 0.61, 0.41, 0.30 µg m−3 h−1 autumn, summer, spring, winter, respectively. Despite similar concentrations former had volatilities and, therefore, showed contributions (46 %–62 latter (14 %–32 contrast, limited low abundances or volatilities, 8 %–12 % %–5 %, Overall, our results improve concentration, seasonal variation, potential impacts can help formulate refined restriction policy specific control areas.

Language: Английский

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Linking gas, particulate, and toxic endpoints to air emissions in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM)

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(9), P. 5043 - 5099

Published: May 4, 2023

Abstract. Chemical mechanisms describe the atmospheric transformations of organic and inorganic species connect air emissions to secondary such as ozone, fine particles, hazardous pollutants (HAPs) like formaldehyde. Recent advances in our understanding several chemical systems shifts drivers chemistry warrant updates used transport models Community Multiscale Air Quality (CMAQ) modeling system. This work builds on Regional Atmospheric Chemistry Mechanism version 2 (RACM2) develops Multiphase (CRACMM) 1.0, which demonstrates a fully coupled representation leading ozone aerosol (SOA) with consideration HAPs. CRACMMv1.0 includes 178 gas-phase species, 51 particulate 508 reactions spanning heterogeneous pathways. To support estimation health risks associated HAPs, nine CRACMM cover 50 % total cancer 60 non-cancer emission-weighted toxicity estimated for primary HAPs from anthropogenic biomass burning sources US, coverage higher (> 80 %) when formaldehyde acrolein are considered. In addition, new mechanism were added based importance their aerosol, or burden reactive carbon (ROC): sesquiterpenes, furans, propylene glycol, alkane-like low- intermediate-volatility compounds (9 species), oxygenated (16 aromatic hydrocarbons (2 slowly reacting carbon. Intermediate- lower-volatility increase ROC by 40 compared current operational mechanisms. Autoxidation, reaction particularly effective producing SOA, was C10 larger alkanes, hydrocarbons, monoterpene including second-generation aldehydes. Integrating radical SOA put additional constraints both enabled implementation previously unconsidered pathways phenolic furanone compounds, predicted account ∼ 30 hydrocarbon under typical conditions. found span atmospherically relevant range number, number oxygens per carbon, oxidation state slight high bias hydrogens total, 11 emitted implemented precursors CMAQv5.3.3 representations, resulting bottom-up prediction is required accurate source attribution design control strategies. available CMAQv5.4.

Language: Английский

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Chlorine-Tolerant Chlorobenzene Combustion over Mullite Catalysts via In Situ Constructing Ru–O–Mn Sites

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 11, 2025

The catalytic combustion of chlorine-containing volatile organic compounds (CVOCs) at low temperatures still faces chlorine poisoning challenges. Herein, chlorine-tolerant chlorobenzene over manganese-based mullite (SmMn2O5) catalysts has been originally demonstrated via in situ constructing rich Ru-O-Mn sites, engineered from the doping ruthenium (Ru) and subsequent etching samarium (Sm). Such exhibited 90% activity for 258 °C maintained about 80% after 30 h stability test. Specifically, Ru could readily replace Mn4+ SmMn2O5 to form Sm expose more surface which significantly enhanced redox capacity oxygen activation ability, thus improving low-temperature chlorobenzene. Besides, sites boosted transformation intermediate species low-pollution accelerated removal Cl formation CO2, enhancing tolerance catalysts. This study deepened understanding mechanism provided a feasible strategy development high-efficiency chlorine-resistant CVOCs.

Language: Английский

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Development and evaluation of a new compact mechanism for aromatic oxidation in atmospheric models

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(24), P. 18351 - 18374

Published: Dec. 17, 2021

Abstract. Aromatic hydrocarbons, including benzene, toluene, and xylenes, play an important role in atmospheric chemistry, but the associated chemical mechanisms are complex uncertain. Sparing representation of this chemistry models is needed for computational tractability. Here, we develop a new compact mechanism aromatic (GC13) that captures current knowledge from laboratory studies with only 17 unique species 44 reactions. We compare GC13 to six other currently used varying complexity box model simulations environmental chamber data diurnal boundary layer show provides results consistent or better than more oxygenated products (alcohols, carbonyls, dicarbonyls), ozone, hydrogen oxide (HOx≡OH+HO2) radicals. Specifically, features increased radical recycling ozone destruction phenoxy–phenylperoxy cycling relative mechanisms. implement into GEOS-Chem global transport find higher glyoxal yields net loss compared oxidation contributes 23 %, 5 8 % glyoxal, methylglyoxal, formic acid production, respectively, has mixed effects on formaldehyde. It drives small decreases tropospheric OH (−2.2 %), NOx (≡NO+NO2; −3.7 (−0.8 large increase NO3 (+22 %) cycling. Regional polluted environments can be substantially larger, especially photolysis carbonyls produced by oxidation, which wintertime increases concentrations.

Language: Английский

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