Investigation of the reaction pathway of OH radicals produced by Fenton oxidation in the conditions of wastewater treatment

Yoon, Jeyong; Lee, Y; Kim, S

doi:10.2166/wst.2001.0242

Cited by 177 publications

(82 citation statements)

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“…Thus, hydroxyl group addition for benzene under standard conditions is an endogonic reaction (⌬G o Ј ϭ 25.8 kJ/mol) (16). One possible mechanism for overcoming the unfavorable thermodynamics of benzene hydroxylation is through the formation of highly reactive hydroxyl free radicals (HO·), which subsequently attack the aromatic ring (1,16,38). When benzenedegrading cultures of strain RCB with nitrate as the electron acceptor were incubated in the presence of the hydroxyl free radical scavenger sodium iodide (0.5 mM), benzene degradation and subsequent phenol formation were inhibited compared to controls not amended with sodium iodide (Table 1).…”

Section: Mechanism Of Hydroxylationmentioning

confidence: 99%

Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

Chakraborty

Coates

2005

Appl Environ Microbiol

118

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Benzene is a highly toxic industrial compound that is essential to the production of various chemicals, drugs, and fuel oils. Due to its toxicity and carcinogenicity, much recent attention has been focused on benzene biodegradation, especially in the absence of molecular oxygen. However, the mechanism by which anaerobic benzene biodegradation occurs is still unclear. This is because until the recent isolation of Dechloromonas strains JJ and RCB no organism that anaerobically degraded benzene was available with which to elucidate the pathway. Although many microorganisms use an initial fumarate addition reaction for hydrocarbon biodegradation, the large activation energy required argues against this mechanism for benzene. Other possible mechanisms include hydroxylation, carboxylation, biomethylation, or reduction of the benzene ring, but previous studies performed with undefined benzene-degrading cultures were unable to clearly distinguish which, if any, of these alternatives is used. Here we demonstrate that anaerobic nitrate-dependent benzene degradation by Dechloromonas strain RCB involves an initial hydroxylation, subsequent carboxylation, and loss of the hydroxyl group to form benzoate. These studies provide the first pure-culture evidence of the pathway of anaerobic benzene degradation. The outcome of these studies also suggests that all anaerobic benzenedegrading microorganisms, regardless of their terminal electron acceptor, may use this pathway.

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Section: Mechanism Of Hydroxylationmentioning

confidence: 99%

Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

Chakraborty

Coates

2005

Appl Environ Microbiol

118

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“…It can be argued that the possible presence of dissolved oxygen (activated by UV radiation) and photolysis effect were crucial factors for COD removal. The presence of dissolved oxygen, due to the strong mixing conditions, was in effect also confirmed by [31][32][33].…”

Section: Photo-fenton Processmentioning

confidence: 65%

“…Likely, the high presence of organic matter negatively interferes with the Fe 2+ regeneration process, thus leading to the accumulation of H2O2 [33][34][35]: organic matter is an • OH scavenger, involving the interruption of the radical chain reactions that lead to Fe 2+ regeneration through this equation:…”

Section: Fenton Processmentioning

confidence: 99%

H2O2 Based Oxidation Processes for the Treatment of Real High Strength Aqueous Wastes

et al. 2017

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This work was aimed at studying the applicability of H 2 O 2 -based oxidation processes (namely H 2 O 2 /UV, photo-Fenton, and Fenton) for the treatment of six real aqueous wastes. These wastes derived from chemical, pharmaceutical, and detergent production, and were characterised by high COD (chemical oxygen demand) and, in four cases, surfactant concentrations: overall, about 100 tests were conducted. The H 2 O 2 /UV and photo-Fenton processes proved to be very effective in COD removal, the efficiency being greater than 70%. The optimal treatment conditions for the H 2 O 2 /UV process were: 120 min reaction, H 2 O 2 /COD initial dosage ratio = 1/2; the radiation intensity (up to 2000 W·L −1 ) revealed to be a crucial factor, especially in the earlier stage of the process (about 40 min): this aspect can be exploited to reduce the costs related to energy consumption. For the photo-Fenton process the following conditions were chosen: Fe 2+ /H 2 O 2 ratio = 1/30; specific power input = 125 W·L −1 ; H 2 O 2 /COD initial = 1/2; reaction time = 240 min. Photolytic reactions and the presence of dissolved oxygen revealed to be crucial factors for COD removal. The Fenton process, while showing a moderate efficiency (25% COD removal) in the treatment of high loaded wastewaters, provided excellent results in the treatment of aqueous wastes with high content of surfactants. An average yield removal of 70% for non-ionic surfactants (TAS) and 95% for anionic surfactants (MBAS) was obtained, under the following optimal conditions: Fe 2+ /H 2 O 2 = 1/4, H 2 O 2 /COD initial ratio = 1, and contact time = 30 min.

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“…This is because large amount of generation of hydroxyl radical consume dissolved oxygen in the sample. The production of hydroxyl radical within a short period of time results in the depletion of dissolved oxygen and this may reduce the efficiency of the mineralization of organics [14]. By comparing the results of 0.1M, 0.2M, 0.3M & 0.35M for a particular ratio of ferrous to hydrogen peroxide COD is reduced drastically.…”

Section: Cod and Total Solid Variation For Different Molar Ratio Omentioning

confidence: 98%

Treatment of Pharmaceutical Sludge by Fenton Oxidation Process

Nithyanandam¹,

Saravanane²

2013

IJCEA

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Abstract-Fenton Oxidation process was used to treat the pharmaceutical sludge having the COD value of 118, 400 mg/L for the safe disposal. By varying the ratio of ferrous to hydrogen peroxide for different molar ratio (0.1M, 0.2M, 0.3M, 0.35M,0.4 M) of Fenton's reagent the pharmaceutical sludge was treated and COD reductions were calculated and optimum ratio was found out. Sludge was also treated by physical treatment by varying the pH and temperature and COD reductions were calculated and the optimum point was found out. The untreated and treated sludge was subjected to GC-MS for the quantitative analysis of non-biodegradable compounds. Scanning Electron Microscope image acquistation and elemental analysis were also studied for both treated and untreated samples. The purpose of the study is to find the suitable end-use method for reusing the treated and oxidized products.

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Investigation of the reaction pathway of OH radicals produced by Fenton oxidation in the conditions of wastewater treatment

Cited by 177 publications

References 0 publications

Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

H2O2 Based Oxidation Processes for the Treatment of Real High Strength Aqueous Wastes

Treatment of Pharmaceutical Sludge by Fenton Oxidation Process

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