Chemical Oxidation by Photolytic Decomposition of Hydrogen Peroxide

Liao, Chih‐Hsiang; Gurol, Mirat D.

doi:10.1021/es00012a018

Cited by 197 publications

(85 citation statements)

References 17 publications

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“…These mechanistic models are based on known chemical and photochemical principles and can help understanding the often complex chemical mechanisms. They can be of great value during the design and engineering process [16][17][18][19][20][21][22][23][24]. For this reason, the model discussed in this paper belongs to this group.…”

Section: Omentioning

confidence: 99%

Application of a mechanistic UV/hydrogen peroxide model at full-scale: Sensitivity analysis, calibration and performance evaluation

Audenaert

Vermeersch

Hulle

et al. 2011

Chemical Engineering Journal

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Numerous mechanistic models describing the UV/H 2 O 2 process have been proposed in literature. In this study, one of them was used to predict the behavior of a full-scale reactor. The model was calibrated and validated with nonsynthetic influent using different operational conditions. A local sensitivity analysis was conducted to determine the most important operational and chemical model parameters. Based on the latter, the incident UV irradiation intensity and two kinetic rate constants were selected for mathematical estimation. In order to investigate changes of the NOM content over time, some time delay was considered between calibration and validation data collection. Hydrogen peroxide concentration, the decadic absorption coefficient at 310 nm (UVA 310 , as a surrogate for natural organic matter) and pH could be satisfactorily predicted during model validation using an independent data set. It was demonstrated that quick real-time calibration is an option at less controllable full-scale conditions. The reactivity of UVA 310 towards hydroxyl radicals did not show significant variations over time suggesting no need for frequent recalibration. Parameters that determine the initiation step, i.e. photolysis of hydrogen peroxide, have a large impact on most of the variables. Some reaction rate constants were also of importance, but nine kinetic constants did show absolutely no influence to one of the variables. Parameters related to UV shielding by NOM were of main importance. At the conditions used in this study, i.e. H 2 O 2 concentrations between 0.5 and 4 mM, hydraulic residence times between 90 and 200 s and alkalinity concentrations between 2.5 and 6 mM, competitive radiation absorption by NOM was more detrimental to the micro pollutant removal efficiency than hydroxyl radical scavenging. Hydrogen peroxide concentration was classified as a non-sensitive variable, in contrast to the concentration of a micro pollutant which showed to be very to extremely influential to many of the parameters. UV absorption as a NOM surrogate is a promising variable to be included in future models. Model extension by splitting up the UVA 310

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Section: Omentioning

confidence: 99%

Application of a mechanistic UV/hydrogen peroxide model at full-scale: Sensitivity analysis, calibration and performance evaluation

Audenaert

Vermeersch

Hulle

et al. 2011

Chemical Engineering Journal

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“…(8) The formed carbonate radicals are highly selective and react relatively slowly with organic compounds [34]. They may also react with hydrogen peroxide to originate peroxy radical (HO 2 ·) [35] which is a much less reactive species than the hydroxyl radical. Natural organic matter not only acts as a hydroxyl radical scavenger but as explained previously, it can filter the UV light reducing the fraction of the incident light intensity available for hydrogen peroxide [35], which is the major source of hydroxyl radicals in the UV/H 2 O 2 system.…”

Section: Natural Watermentioning

confidence: 99%

“…They may also react with hydrogen peroxide to originate peroxy radical (HO 2 ·) [35] which is a much less reactive species than the hydroxyl radical. Natural organic matter not only acts as a hydroxyl radical scavenger but as explained previously, it can filter the UV light reducing the fraction of the incident light intensity available for hydrogen peroxide [35], which is the major source of hydroxyl radicals in the UV/H 2 O 2 system. The fraction of light absorbed by the hydrogen peroxide was found to be 1.2 to 7.3 fold higher in the Eno River water than in Elizabeth River water at an equivalent UV fluence.…”

Section: Natural Watermentioning

confidence: 99%

Photolysis, oxidation and subsequent toxicity of a mixture of polycyclic aromatic hydrocarbons in natural waters

Shemer

Linden

2007

Journal of Photochemistry and Photobiology A: Chemistry

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Photodegradation of a mixture of three polycyclic aromatic hydrocarbons fluorene (FLU), dibenzofuran (DBF), and dibenzothiophene (DBT) using UV and UV/H 2 O 2 processes was studied. Treating a mixture of the PAHs stimulated a more realistic contamination composition present in polluted water. Effects of pH, PAH concentration, and water matrix composition on removal rates and efficiencies of these compounds are discussed. Batch experiments were conducted using both monochromatic low pressure (LP, 253.7 nm) and polychromatic medium pressure (MP, 200-400 nm) UV sources, in a quasi-collimated beam setup. A synergistic effect was observed during direct photolysis and LP-UV/H 2 O 2 of the mixture as compared to photodegradation as a single component in an aqueous solution. Similar results were obtained for FLU using MP-UV/H 2 O 2 whereas, degradation of DBF and DBT was inhibited in a mixture. Natural water enhanced the direct photolysis compared to laboratory buffered water, whereas, degradation of the PAHs in the natural water was inhibited using UV/H 2 O 2 process. Toxicity testing using a luminescent inhibition bioassay was correlated to intermediates generated during UV-based oxidation reactions.

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“…The scavenging capabilities of humic material and formaldehyde can be compared by estimating the product of the reaction rate constants with the concentration. The rate constant of humic material with hydroxyl radical was reported to be 1.6x10 4 sec -1 (mg/L of DOC) -1 (25), while the rate constant of formaldehyde with hydroxyl radical is 1.0x10 9 M-1 sec -1 (22). Assuming 4 mg/L of DOC for humic material and 17 x10 -3 mg/L of formaldehyde at the peak value, the radical scavenging capabilities of the humic material and formaldehyde are estimated respectively as 64,000 sec -1 and 570 sec -1-, or in other words; only one out of 113 radical is expected to react with formaldehyde.…”

Section: Formaldehyde Formation At Various Ozone Dosagesmentioning

confidence: 99%

Formaldehyde Formation During Ozonation Of Drinking Water

Can

Gurol

2003

Ozone: Science & Engineering

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Partial oxidation of natural organic material during ozonation produces oxygenated by-products of low molecular weight. Formaldehyde, being the most common oxygenated by-product of ozone, is considered to be a problematic compound by the water industry due to its potential adverse health effects. This research attempts to provide specific information on the effects of water quality parameters, specifically, pH and alkalinity, the structure of humic material, and the operational parameters, e.g., ozone dosage and contact time, on generation of formaldehyde.The results showed that ozonation caused almost an immediate formation of formaldehyde, which reached a peak value, and then started to decrease with continued ozonation. Ozonation of aqueous fulvic acid produced higher concentrations of formaldehyde compared to other types of humic material. Formaldehyde formation was suppressed by high bicarbonate levels, and enhanced at higher pH. Formaldehyde accumulation was more dramatic at low ozone dosages.

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Chemical Oxidation by Photolytic Decomposition of Hydrogen Peroxide

Cited by 197 publications

References 17 publications

Application of a mechanistic UV/hydrogen peroxide model at full-scale: Sensitivity analysis, calibration and performance evaluation

Application of a mechanistic UV/hydrogen peroxide model at full-scale: Sensitivity analysis, calibration and performance evaluation

Photolysis, oxidation and subsequent toxicity of a mixture of polycyclic aromatic hydrocarbons in natural waters

Formaldehyde Formation During Ozonation Of Drinking Water

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