Assessing the Use of Probes and Quenchers for Understanding the Reactive Species in Advanced Oxidation Processes

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(13), P. 5433 - 5444

Published: March 17, 2023

Advanced oxidation processes (AOPs) are increasingly applied in water and wastewater treatment. Understanding the role of reactive species using probes quenchers is one main requirements for good process design. However, much fundamental kinetic data reactions with lacking, probably leading to inappropriate probe quencher selection dosing. In this work, second-order rate constants over 150 such as •OH, SO4•-, Cl• chemical oxidants free chlorine persulfate were determined. Some previously ill-quantified (e.g., furfuryl alcohol methyl phenyl sulfoxide certain oxidants, nitrobenzene 1,4-dioxane halogen radicals) found be kinetically favorable. The specific can guided by improved database. criteria properly choosing dosages proposed along a procedure quantifying interference from addition. limitations approaches explicated, possible solutions combination other tools) proposed. Overall, database protocols provided work benefit future research understanding radical chemistry AOPs well radical-involved processes.

Language: Английский

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Multiple Roles of Dissolved Organic Matter in Advanced Oxidation Processes

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(16), P. 11111 - 11131

Published: July 7, 2022

Advanced oxidation processes (AOPs) can degrade a wide range of trace organic contaminants (TrOCs) to improve the quality potable water or discharged wastewater effluents. Their effectiveness is impacted, however, by dissolved matter (DOM) that ubiquitous in all sources. During application an AOP, DOM scavenge radicals and/or block light penetration, therefore impacting their toward contaminant transformation. The multiple ways which different types sources impact oxidative purification are critically reviewed. inhibit degradation TrOCs, but it also enhance formation and reactivity useful for elimination alter transformation pathways contaminants. An in-depth analysis highlights inhibitory effect on efficiency TrOCs based DOM's structure optical properties its oxidants as well synergistic contribution from redox transient intermediates. AOPs influence types, mechanisms, extent byproducts formation. Research needs proposed advance practical understanding how be exploited purification.

Language: Английский

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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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Reactivity of Chlorine Radicals (Cl^• and Cl₂^•–) with Dissolved Organic Matter and the Formation of Chlorinated Byproducts

Environmental Science & Technology, Journal Year: 2020, Volume and Issue: 55(1), P. 689 - 699

Published: Dec. 21, 2020

Chlorine radicals, including Cl• and Cl2•-, can be produced in sunlight waters (rivers, oceans, lakes) or water treatment processes (e.g., electrochemical advanced oxidation processes). Dissolved organic matter (DOM) is a major reactant with, scavenger of, Cl2•- water, but limited quantitative information exists regarding the influence of DOM structure on its reactivity with Cl2•-. This study aimed at quantifying reaction rates formation chlorinated byproducts from reactions DOM. Laser flash photolysis experiments were conducted to quantify second-order rate constants 19 isolates (kDOM-Cl•) (kDOM-Cl2•-), compare those hydroxyl radical (kDOM-•OH). The values for kDOM-Cl• ((3.71 ± 0.34) × 108 (1.52 1.56) 109 MC-1 s-1) orders magnitude greater than kDOM-Cl2•- ((4.60 0.90) 106 (3.57 0.53) 107 s-1). negatively correlated weight-averaged molecular weight (MW) due diffusion-controlled reactions. high aromaticity total antioxidant capacity tended react faster During same experiments, we also monitored through evolution chlorine (TOCl) as function oxidant exposure (CT value). Maximum TOCl occurred CT 4-8 10-12 M·s 1.1-2.2 10-10 These results signify importance scavenging radicals potential risks producing unknown toxicity.

Language: Английский

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The Role of Dissolved Organic Matter Composition in Determining Photochemical Reactivity at the Molecular Level

Environmental Science & Technology, Journal Year: 2019, Volume and Issue: 53(20), P. 11725 - 11734

Published: Sept. 11, 2019

Dissolved organic matter (DOM) composition influences its ability to form photochemically produced reactive intermediates (PPRI). While relationships have been established between bulk DOM properties and triplet (3DOM) singlet oxygen (1O2) quantum yields, contradictory evidence exists for hydroxyl radical (•OH) hydroxylating species. Furthermore, little is known about these at the molecular level. We evaluated photochemical reactivity of water samples from a wastewater treatment plant St. Louis River in Minnesota Wisconsin, U.S.A. Bulk characterization using ultraviolet-visible spectroscopy demonstrates that color apparent size decrease downstream, while analysis Fourier-transform ion cyclotron resonance mass spectrometry reveals saturation chemodiversity highest near Lake Superior. 3DOM yield coefficients 1O2 yields increase downstream correlate strongly with saturated formulas. Similar results are observed carbon-normalized photodegradation rate constants atorvastatin, carbamazepine, venlafaxine, which react primarily 1O2. In contrast, •OH lowest less saturated, more oxygenated DOM, suggesting not major precursor. Mixed DEET, reacts multiple PPRI. Molecular-level compositional data reveal insights into differing formation pathways individual PPRI, but information specific contaminants needed predict their fate.

Language: Английский

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A review on the degradation efficiency, DBP formation, and toxicity variation in the UV/chlorine treatment of micropollutants

Chemical Engineering Journal, Journal Year: 2021, Volume and Issue: 424, P. 130053 - 130053

Published: May 16, 2021

Language: Английский

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Particulate nitrate photolysis in the atmosphere

Environmental Science Atmospheres, Journal Year: 2022, Volume and Issue: 2(2), P. 111 - 127

Published: Jan. 1, 2022

Particulate nitrate photolysis can lead to the formation of secondary inorganic and organic aerosols that affect climate, air quality, human health.

Language: Английский

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Critical Review of UV-Advanced Reduction Processes for the Treatment of Chemical Contaminants in Water

ACS Environmental Au, Journal Year: 2022, Volume and Issue: 2(3), P. 178 - 205

Published: Feb. 14, 2022

UV-advanced reduction processes (UV-ARP) are an advanced water treatment technology characterized by the reductive transformation of chemical contaminants. Contaminant abatement in UV-ARP is most often accomplished through reaction with hydrated electrons (eaq–) produced from UV photolysis sensitizers (e.g., sulfite). In this Review, we evaluate photochemical kinetics, substrate scope, and optimization UV-ARP. We find that quantities typically reported studies natural engineered systems under-reported literature, especially formation rates, scavenging capacities, concentrations key reactive species like eaq–. The absence these has made it difficult to fully impact operating conditions role matrix components on efficiencies scope weighted heavily toward contaminant classes resistant degradation oxidation processes, oxyanions per- polyfluoroalkyl substances. Some have sought optimize contaminants; however, a thorough evaluation dissolved organic matter strategies needed. Overall, data compilation, analysis, research recommendations provided Review will assist community future efforts optimizing systems, modeling eaq–-based developing new systems.

Language: Английский

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A critical review on reliability of quenching experiment in advanced oxidation processes

Chemical Engineering Journal, Journal Year: 2023, Volume and Issue: 466, P. 143161 - 143161

Published: April 23, 2023

Language: Английский

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Degradation of Perfluorooctanoic Acid by Chlorine Radical Triggered Electrochemical Oxidation System

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(25), P. 9416 - 9425

Published: June 9, 2023

Electrochemical oxidation (EO) has been shown to have the unique ability degrade perfluorooctanoic acid (PFOA), although radical chemistry involved in this degradation is unclear, particularly presence of chloride ions (Cl–). In study, reaction kinetics, free quenching, electron spin resonance, and probes were used examine roles ·OH reactive chlorine species (RCS, including Cl·, Cl2•–, ClO·) EO PFOA. Using NaCl, PFOA rates 89.4%–94.9% defluorination 38.7%–44.1% achieved after 480 min with concentrations ranging from 2.4 240 μM. The occurred via synergistic effect Cl· rather than through direct anodic oxidation. products density functional theory (DFT) calculations revealed that triggered first step reaction, thus initial transfer was not rate-limiting degradation. change Gibbs energy caused by 65.57 kJ mol–1, which more two times lower ·OH. However, subsequent demonstrated for time promising development electrochemical technology remove perfluorinated alkyl substances environment.

Language: Английский

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