Estimation of .OH radical reaction rate constants for phenol and chlorinated phenols using UV/H2O2 photo-oxidation.
TL;DR: A mechanistic model for UV/H2O2 photooxidation has been developed and room temperature (27 degrees C) rate constants for the reaction of .OH radical with the substrates have been estimated by using the model equation.
About: This article is published in Journal of Hazardous Materials.The article was published on 1999-01-01. It has received 97 citations till now. The article focuses on the topics: Reaction rate constant & Radical.
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TL;DR: In this article, the effectiveness of pure and modified TiO2 for photocatalytic degradation of different organic matters and clarifies the advantages of the modifiedTiO2 with photoactivity under visible light.
523 citations
TL;DR: The results indicate that the dye can be most effectively oxidized in aqueous solution at dye:Fe(2+):H2O2 molar ratio of 1:1.1, which corresponds to about 81% reduction of the initial COD.
445 citations
TL;DR: Degradation experiments with various structurally distinct compounds were carried out, indicating a similar selectivity of the heterogeneous Fenton-like system to that known for oxidation with ·OH.
236 citations
TL;DR: The chlorophenols photo-degradation kinetics and mechanism in the aquatic environment under UV-vis in the presence of hydroxyl radicals and singlet oxygen is presented and pathways for intermediate reactions e.g. dechlorination, oxidation, dimerization are presented.
235 citations
TL;DR: In this paper, the effects of UV lamp power and H2O2 concentration on NO and SO2 removal efficiencies were studied in an ultraviolet (UV)-bubble column reactor, and the results showed that under all conditions, SO2 achieved 100% removal.
235 citations
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01 Jan 1992
TL;DR: The most widely read reference in the water industry, Water Industry Reference as discussed by the authors, is a comprehensive reference tool for water analysis methods that covers all aspects of USEPA-approved water analysis.
Abstract: Set your standards with these standard methods. This is it: the most widely read publication in the water industry, your all-inclusive reference tool. This comprehensive reference covers all aspects of USEPA-approved water analysis methods. More than 400 methods - all detailed step-by-step; 8 vibrant, full-color pages of aquatic algae illustrations; Never-before-seen figures that will help users with toxicity testing and the identification of apparatus used in the methods; Over 300 superbly illustrated figures; A new analytical tool for a number of inorganic nonmetals; Improved coverage of data evaluation, sample preservation, and reagant water; And much more!
78,324 citations
TL;DR: In this article, the theoretical and practical yield of OH from O3 at high pH, 03/H202, O3/UV and H2O2/UV systems are reviewed.
Abstract: Advanced oxidation processes are defined as those which involve the generation of hydroxyl radicals in sufficient quantity to affect water purification. The theoretical and (practical yield of OH from O3 at high pH, 03/H202, O3/UV and H2O2/UV systems is reviewed. New data is presented which illustrates the importance of direct photolysis in the O3/UV process, the effect of the H202:03 ratio in the O3/H2O2 process, and the impact of the low extinction coefficient of H2O2 in the H202/UV process.
1,663 citations
TL;DR: The application status and potential of three chemical oxidation treatment methods which generate powerful oxidants (hydroxyl radicals): ultraviolet light (UV)/hydrogen peroxide (H2O2) process, Fenton's reagent treatment, and titanium dioxide (TiO2)-assisted photocatalytic degradation, are described and discussed in this paper.
Abstract: The application status and potential of three chemical oxidation treatment methods which generate powerful oxidants (hydroxyl radicals): ultraviolet light (UV)/hydrogen peroxide (H2O2) process, Fenton's reagent treatment, and titanium dioxide (TiO2)-assisted photocatalytic degradation, are described and discussed. These oxidation methods are known to effectively degrade and, in several cases, mineralize contaminants ranging from inorganic compounds (such as cyanides) to chlorinated aliphatic compounds and complex aromatic compounds in reaction times on the order of a few minutes to a few hours. Of the three oxidation systems discussed, the technology for the UV/H2O2 process is the most advanced, with numerous successful full-scale treatment units already in existence. Applications of both the Fenton's reagent and TiO2-assisted photodegradation processes are currently being developed, with the concepts proven in numerous laboratory-scale studies for a wide range of contaminants. However, both of t...
321 citations
TL;DR: In this article, the photoassisted oxidation of pentachlorophenol (PCP) in TiO_2 particle suspensions was investigated, and complete dechlorination of 47 µM PCP was achieved after 3 h of illumination at high intensity with apparent quantum efficiencies ranging from 1 to 3%.
Abstract: The photoassisted oxidation of pentachlorophenol (PCP) in TiO_2 particle suspensions was investigated. Complete dechlorination of 47 µM PCP was achieved after 3 h of illumination at high intensity with apparent quantum efficiencies (ΦPCP, ΦCI, ΦH+, ΦH_2O_2) ranging from 1 to 3%. p-Chloranil, tetrachlorohydroquinone, H_2O_2, and o-chloranil were formed as the principal intermediates. Formate and acetate were formed as products during the latter stages of photooxidation. The mechanism for photooxidation of PCP proceeds via hydroxyl radical attack on the para position of the PCP ring to form a semiquinone radical which in turn disproportionates to yield p-chloranil and tetrachlorohydroquinone. Under high-intensity illumination, the reaction intermediates are attacked further by •OH to yield HCO_2^-, CH_3CO_2^-, CO_2, H^+, and Cl^-.
232 citations
TL;DR: In this article, the performance of photolysis of polynuclear aromatic hydrocarbons, including fluorene, phenanthrene, and acenaphthene, was investigated.
Abstract: Direct photolysis with UV radiation (254 nm) and oxidation with ozone combined with UV radiation of three polynuclear aromatic hydrocarbons, fluorene, phenanthrene, and acenaphthene, has been studied. Quantum yields of the direct photolysis of the PAHs determined were 7.5 {times} 10{sup {minus}3}, 6.9 {times} 10{sup {minus}3}, and 52 {times} 10{sup {minus}3} mol(photon){sup {minus}1} for fluorene, phenanthrene, and acenaphthene, respectively. Contributions of direct ozonation, direct photolysis, and radical oxidation have also been estimated for the oxidation with ozone combined with UV radiation. Fluorene is oxidized by direct photolysis and radical reactions, phenanthrene through direct mechanisms, ozonation, and photolysis, and acenaphthene mainly by direct ozonation.
158 citations