Free-Radical-Induced Oxidative and Reductive Degradation of Fluoroquinolone Pharmaceuticals: Kinetic Studies and Degradation Mechanism

2009 ◽  
Vol 113 (27) ◽  
pp. 7846-7851 ◽  
Author(s):  
Hanoz Santoke ◽  
Weihua Song ◽  
William J. Cooper ◽  
John Greaves ◽  
George E. Miller
Keyword(s):  
Free Radical ◽  
Degradation Mechanism ◽  
Kinetic Studies ◽  
Reductive Degradation

Free-radical-induced oxidative and reductive degradation of N,N′-diethyl-m-toluamide (DEET): Kinetic studies and degradation pathway

2009 ◽  
Vol 43 (3) ◽  
pp. 635-642 ◽  
Author(s):  
Weihua Song ◽  
William J. Cooper ◽  
Barrie M. Peake ◽  
Stephen P. Mezyk ◽  
Michael G. Nickelsen ◽  
...  
Keyword(s):  
Free Radical ◽  
Kinetic Studies ◽  
Degradation Pathway ◽  
Reductive Degradation

Free-Radical-Induced Oxidative and Reductive Degradation of Fibrate Pharmaceuticals: Kinetic Studies and Degradation Mechanisms

2009 ◽  
Vol 113 (7) ◽  
pp. 1287-1294 ◽  
Author(s):  
Behnaz Razavi ◽  
Weihua Song ◽  
William J. Cooper ◽  
John Greaves ◽  
Joonseon Jeong
Keyword(s):  
Free Radical ◽  
Kinetic Studies ◽  
Degradation Mechanisms ◽  
Reductive Degradation

Aqueous free-radical polymerization of PEGMEMA macromer: kinetic studies via an on-line 1H NMR technique

2012 ◽  
Vol 21 (10) ◽  
pp. 683-688 ◽  
Author(s):  
Vahid Najafi ◽  
Farshid Ziaee ◽  
Kourosh Kabiri ◽  
Mohammad Jalal Zohouriaan Mehr ◽  
Hossein Abdollahi ◽  
...  
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
1H Nmr ◽  
Free Radical Polymerization ◽  
Kinetic Studies ◽  
On Line

scholarly journals The MCM v3.3 degradation scheme for isoprene

2015 ◽  
Vol 15 (6) ◽  
pp. 9709-9766 ◽  
Author(s):  
M. E. Jenkin ◽  
J. C. Young ◽  
A. R. Rickard
Keyword(s):  
Boundary Layer ◽  
Free Radical ◽  
Degradation Mechanism ◽  
Closed Shell ◽  
Chemical Mechanism ◽  
Formation Mechanisms ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Radical Species ◽  
Master Chemical Mechanism

Abstract. The chemistry of isoprene degradation in the Master Chemical Mechanism (MCM) has been systematically refined and updated to reflect recent advances in understanding, with these updates appearing in the latest version, MCM v3.3. The complete isoprene degradation mechanism in MCM v3.3 consists of 1935 reactions of 605 closed shell and free radical species, which treat the chemistry initiated by reaction with OH radicals, NO3 radicals and ozone (O3). A detailed overview of the updates is provided, within the context of reported kinetic and mechanistic information. The revisions mainly relate to the OH-initiated chemistry, which tends to dominate under atmospheric conditions, although these include updates to the chemistry of some products that are also generated from the O3 - and NO3-initiated oxidation. The revisions have impacts in a number of key areas, including HOx recycling, NOx recycling and the formation of species reported to play a role in SOA-formation mechanisms. The performance of the MCM v3.3 isoprene mechanism has been compared with those of earlier versions (MCM v3.1 and MCM v3.2) over a range of relevant conditions, using a box model of the tropical forested boundary layer. The results of these calculations are presented and discussed, and are used to illustrate the impacts of the mechanistic updates in MCM v3.3.

scholarly journals Degradation of Diallyl Phthalate (DAP) by Fenton Oxidation: Mechanistic and Kinetic Studies

2018 ◽  
Vol 9 (1) ◽  
pp. 23
Author(s):  
Sondos Dbira ◽  
Nasr Bensalah ◽  
Moustafa Zagho ◽  
Ahmed Bedoui
Keyword(s):  
High Performance ◽  
Hplc Analysis ◽  
Degradation Mechanism ◽  
Kinetic Studies ◽  
Cost Effective ◽  
Fenton Oxidation ◽  
Fenton’S Reaction ◽  
Toc Removal ◽  
Initial Ph ◽  
Diallyl Phthalate

In this work, the degradation and mineralization of Diallyl Phthalate (DAP) in water by Fenton oxidation was investigated. The effects of different experimental parameters including the initial pH, the hydrogen peroxide (H2O2) dose, the catalyst (Fe2+) dose, the iron source, and the DAP concentration on the rate and the yield of DAP degradation by Fenton oxidation were evaluated. DAP and its intermediates were quantified by high performance liquid chromatography (HPLC) analysis and the measurement of total organic carbon (TOC) during Fenton oxidation. The results obtained confirmed that hydroxyl radicals (HO•) generated from Fenton’s reaction were capable of completely eliminating DAP from water. Fenton oxidation of 100 mg/L DAP aqueous solution at pH = 3.2 required 1000 mg/L H2O2 and 50 mg/L Fe2+. Under these conditions, more than TOC removal exceeded 95% after 300 min Fenton oxidation. The competition kinetics method was used to determine an absolute rate constant of 7.26.109 M−1 s−1 for the reaction between DAP and HO• radicals. HPLC analysis showed that phthalic acid, 1,2-dihydroxybenzene, 1,2,4-trihydroxybenzene, maleic acid, formic acid and oxalic acid were the main intermediates formed during DAP degradation. Accordingly, a simple DAP degradation mechanism by the Fenton reaction was proposed. These promising results proved the potential of Fenton oxidation as a cost-effective method for the decontamination of wastewaters containing phthalates.

scholarly journals Effect of Natural Organic Matter on the Ozonation Mechanism of Trimethoprim in Water

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2935
Author(s):  
Ning Zhang ◽  
Beihai Zhou ◽  
Rongfang Yuan ◽  
Fei Wang ◽  
Huilun Chen
Keyword(s):  
Organic Matter ◽  
Free Radical ◽  
Natural Organic Matter ◽  
Removal Efficiency ◽  
Bacterial Infections ◽  
Degradation Mechanism ◽  
Degradation Pathways ◽  
Ozonation Time ◽  
Direct Hydroxylation ◽  
Fluorescence Peak

Trimethoprim (TMP) is often used for the treatment of various bacterial infections. It can be detected in water, and it is difficult to be biodegraded. In this study, the degradation mechanism of TMP through ozonation and the effect of humic acids (HA) were investigated. Excessive ozone (pH 6, 0 °C) could reduce the content of TMP to less than 1% in 30 s. However, when ozone (O3) was not excessive (pH 6, 20 °C), the removal efficiency of TMP increased with the increase of O3 concentration. Four possible degradation pathways of TMP in the process of ozonation were speculated: hydroxylation, demethylation, carbonylation, and cleavage. The presence of HA in water inhibit the generation of ozonation products of TMP. The excitation-emission matrices (EEM) analysis showed that with the extension of ozonation time, the fluorescence value in the solution decreased and the fluorescence peak blue shifted. These results indicated that the structure of HA changed in the reaction and was competitively degraded with TMP. According to the free radical quenching test, the products of pyrolysis, direct hydroxylation and demethylation were mainly produced by indirect oxidation.

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