Autoxidation of SIV inhibited by chlorophenols reacting with sulfate radicals

2007 ◽  
Vol 4 (5) ◽  
pp. 355 ◽  
Author(s):  
Józef Ziajka ◽  
Krzysztof J. Rudzinski

Environmental context. Chlorophenols pollute natural waters and soils, as well as urban waste water systems. Although toxic and carcinogenic to animals and humans, a detailed knowledge of their action is limited. A new approach to effective degradation in the environment is advanced oxidation processes with sulfate radicals. The radicals can originate from the oxidation of sulfur dioxide or sulfites to make these common pollutants and food additives interact with chlorophenols. The main goal of this work is to determine rate constants for reactions of these chlorophenols with sulfate radicals in order to shed some light on the chemical kinetics of these reactions. Abstract. Kinetic experiments have shown that six chlorophenols (CPs) inhibit the autoxidation of SIV catalysed by Fe(ClO4)3 in aqueous solution at 25°C and pH ≈ 3.0. Efficiency of the inhibition decreases with the number of chlorine substituents for all CPs except for 2,5-dichlorophenol (2,5-DCP), which ranked between the tri- and tetrachlorophenols. The inhibition is explained by reactions of chlorophenols with sulfate radicals, the chain carriers in the mechanism of autoxidation. Rate constants for these reactions are determined for the first time, using the reversed-rates method with ethanol as a reference inhibitor: 8.7 × 109 (4-CP), 7.4 × 109 (2,4-DCP), 1.9 × 109 (2,5-DCP), 2.4 × 109 (2,4,5-TCP), 2.9 × 109 (2,4,6-TCP), and 7.5 × 108 (2,3,5,6-TTCP); 4.3 × 107 (ethanol reference) M–1 s–1. Linear correlations were derived for the estimation of rate constants for the remaining chlorophenols using sums of Brown substituent coefficients or relative strengths of O–H bonds. The results can be used in the development of advanced oxidation processes that utilise sulfate radicals for mineralisation of chlorophenols in wastewaters, and also demonstrate that chlorophenols can extend the lifetimes of SO2 and sulfites in natural and atmospheric waters.

2011 ◽  
Vol 11 (1) ◽  
pp. 129-134 ◽  
Author(s):  
A. Dulov ◽  
N. Dulova ◽  
Y. Veressinina ◽  
M. Trapido

The degradation of propoxycarbazone-sodium, an active component of commercial herbicide, in aqueous solution with ozone, UV photolysis and advanced oxidation processes: O3/UV, O3/UV/H2O2, H2O2/UV, and the Fenton process was studied. All these methods of degradation proved feasible. The kinetics of propoxycarbazone-sodium degradation in water followed the pseudo-first order equation for all studied processes except the Fenton treatment. The application of schemes with ozone demonstrated low pseudo-first order rate constants within the range of 10−4 s−1. Addition of UV radiation to the processes improved the removal of propoxycarbazone-sodium and increased the pseudo-first order rate constants to 10−3 s−1. The Fenton process was the most efficient and resulted in 5 and 60 s of half-life and 90% conversion time of propoxycarbazone-sodium, respectively, at 14 mM H2O2 concentration. UV treatment and the Fenton process may be recommended for practical application in decontamination of water or wastewater.


2020 ◽  
Vol 6 (10) ◽  
pp. 2800-2815
Author(s):  
Jelena Molnar Jazić ◽  
Tajana Đurkić ◽  
Bojan Bašić ◽  
Malcolm Watson ◽  
Tamara Apostolović ◽  
...  

In water treatment, the application of advanced oxidation processes (AOPs) which involve the generation of not only hydroxyl but also sulfate radicals has recently attracted increasing attention worldwide.


Author(s):  
Zahia Benredjem ◽  
Karima Barbari ◽  
Imene Chaabna ◽  
Samia Saaidia ◽  
Abdelhak Djemel ◽  
...  

Abstract The Advanced Oxidation Processes (AOPs) are promising environmentally friendly technologies for the treatment of wastewater containing organic pollutants in general and particularly dyes. The aim of this work is to determine which of the AOP processes based on the Fenton reaction is more effective in degrading the methyl orange (MO) dye. The comparative study of the Fenton, photo-Fenton (PF) and electro-Fenton (EF) processes has shown that electro-Fenton is the most efficient method for oxidizing Methyl Orange. The evolution of organic matter degradation was followed by absorbance (discoloration) and COD (mineralization) measurements. The kinetics of the MO degradation by the electro-Fenton process is very rapid and the OM degradation rate reached 90.87% after 5 min. The influence of some parameters such as the concentration of the catalyst (Fe (II)), the concentration of MO, the current density, the nature and the concentration of supporting electrolyte was investigated. The results showed that the degradation rate increases with the increase in the applied current density and the concentration of the supporting electrolyte. The study of the concentration effect on the rate degradation revealed optimal values for the concentrations 2.10−5 M and 75 mg L−1 of Fe (II) and MO respectively.


1996 ◽  
Vol 122 (1) ◽  
pp. 58-62 ◽  
Author(s):  
Andrew Hong ◽  
Mark E. Zappi ◽  
Chiang Hai Kuo ◽  
Donald Hill

Author(s):  
Tatek Temesgen ◽  
Mooyoung Han

Abstract In this study, the influence of nanobubbles (NBs) application in ozone (O3) based advanced oxidation processes (AOP) is investigated. The results demonstrate the potential of NBs application to O3 – based AOP. It was observed that NBs suppress the negative influence of pH and operating temperatures on the efficiency of ozonation. In addition, the application of NBs tends to improve the solubility of O3 and the rate of mass transfer under the influence of a broad range of temperature and pH conditions. The results of this research indicate that application of NBs minimized the reduction in concentration of dissolved O3 with an increase in temperature. Furthermore, application of NBs highly improved the OH radical formation in acidic conditions. The results of this research depicted for first time that the application of NBs strongly encourages the initiation of reactions involving OH radicals. It was found by this research that NBs can boost the concentration of OH radicals up to 3.5 fold compared to equivalent MB supported ozonation systems. This is assumed to improve the efficiency of currently existing conventional bubble supported O3 – based AOP systems.


2019 ◽  
Vol 17 (2) ◽  
pp. 254-265 ◽  
Author(s):  
A. Derbalah ◽  
M. Sunday ◽  
R. Chidya ◽  
W. Jadoon ◽  
H. Sakugawa

Abstract In this study, the kinetics of photocatalytic removal of imidacloprid, a systemic chloronicotinoid insecticide, from water using two advanced oxidation systems (ZnO(normal)/H2O2/artificial sunlight and ZnO(nano)/H2O2/artificial sunlight) were investigated. Moreover, the effects of pH, insecticide concentration, catalyst concentration, catalyst particle size, and water type on the photocatalytic removal of imidacloprid were evaluated. Furthermore, total mineralization of imidacloprid under these advanced oxidation systems was evaluated by monitoring the decreases in dissolved organic carbon (DOC) concentrations and formation rate of inorganic ions (Cl− and NO2−) with irradiation time using total organic carbon (TOC) analysis and ion chromatography to confirm the complete detoxification of imidacloprid in water. The degradation rate of imidacloprid was faster under the ZnO(nano)/H2O2/artificial sunlight system than the ZnO(normal)/artificial sunlight system in both pure and river water. The photocatalytic degradation of imidacloprid under both advanced oxidation systems was affected by pH, catalyst concentration, imidacloprid concentration, and water type. Almost complete mineralization of imidacloprid was only achieved in the ZnO(nano)/H2O2/artificial sunlight oxidation system. The photogeneration rate of hydroxyl radicals was higher under the ZnO(nano)/H2O2/artificial sunlight system than the ZnO(normal)/H2O2/artificial sunlight system. Advanced oxidation processes, particularly those using nanosized zinc oxide, can be regarded as an effective photocatalytic method for imidacloprid removal from water.


2018 ◽  
Vol 7 (1) ◽  
pp. 61-67
Author(s):  
Do Ngoc Khue ◽  
Tran Dai Lam ◽  
Dao Duy Hung ◽  
Vu Quang Bach ◽  
Nguyen Van Anh ◽  
...  

AbstractSeveral advanced oxidation processes have been performed for the decomposition of ester nitrates (ENs), such as nitroglycerine (NG) and pentaerythritol tetranitrate (PETN). The reaction kinetics for removing NG and PETN by some of the advanced oxidation processes (e.g. UV-H2O2, Fenton, UV-Fenton) followed the pseudo-first-order model. The reaction rates in different systems followed the sequence ENs/UV<ENs/H2O2<ENs/UV-H2O2<ENs/Fenton<ENs/UV-Fenton. The effect of various parameters, such as pH, concentration of hydrogen peroxide, and temperature, on the degradation of NG and PETN were studied.


Chemosphere ◽  
2016 ◽  
Vol 144 ◽  
pp. 1780-1787 ◽  
Author(s):  
Tarun Anumol ◽  
Sonia Dagnino ◽  
Darcy R. Vandervort ◽  
Shane A. Snyder

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