Electrochemical Oxidation of 6:2 Polyfluoroalkyl Phosphate Diester—Simulation of Transformation Pathways and Reaction Kinetics with Hydroxyl Radicals

2021 ◽  
Author(s):  
Jonathan Zweigle ◽  
Boris Bugsel ◽  
Markus Schmitt ◽  
Christian Zwiener
Keyword(s):  
Reaction Kinetics ◽  
Electrochemical Oxidation ◽  
Hydroxyl Radicals ◽  
Phosphate Diester ◽  
Transformation Pathways

Reaction kinetics on treatment of food industry wastewaters by electrochemical oxidation

2013 ◽  
Vol 52 (37-39) ◽  
pp. 7092-7100 ◽  
Author(s):  
Güray Güven ◽  
N. Altιnay Perendeci ◽  
Abdurrahman Tanyolaç
Keyword(s):  
Reaction Kinetics ◽  
Electrochemical Oxidation ◽  
Food Industry

scholarly journals Modeling the Mineralization Kinetics of Visible Led Graphene Oxide/Titania Photocatalytic Ozonation of an Urban Wastewater Containing Pharmaceutical Compounds

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1256
Author(s):  
Fernando J. Beltrán ◽  
Manuel Checa ◽  
Javier Rivas ◽  
Juan F. García-Araya
Keyword(s):  
Free Radical ◽  
Kinetic Model ◽  
Hydroxyl Radical ◽  
Reaction Kinetics ◽  
Hydroxyl Radicals ◽  
Reaction Rate ◽  
Pharmaceutical Compounds ◽  
Urban Wastewater ◽  
Photocatalytic Ozonation ◽  
Liquid Reaction

In a water ozonation process, dissolved organics undergo two reactions at least: direct ozone attack and oxidation with hydroxyl radicals generated from the ozone decomposition. In the particular case of urban wastewater contaminated with pharmaceuticals, competition between these two reactions can be studied through application of gas–liquid reaction kinetics. However, there is a lack in literature about kinetic modeling of ozone processes in water specially in photocatalytic ozonation. In this work, lumped reactions of ozone and hydroxyl radicals with total organic carbon have been proposed. Urban wastewater containing a mixture of eight pharmaceutical compounds has been used to establish the kinetic model that simulates the mineralization process. The kinetic model is based on a mechanism of free radical and molecular reactions and the knowledge of mass transfer, chemical reaction rate constants, and radiation transfer data. According to the model, both single ozonation and photocatalytic ozonation present two distinct reaction periods characterized by the absence and presence of dissolved ozone. In the first period (less than 10 min), pharmaceuticals mainly disappear by direct ozone reactions and TOC variation due to these compounds has been modeled according to gas–liquid reaction kinetics through a lumped ozone-pharmaceutical TOC fast second order reaction. The corresponding rate constant of this reaction was found to change with time from 3 × 105 to 200 M−1 s−1 with Hatta values higher than 0.3. In the second period (nearly 5 h), competition between direct and hydroxyl radical reactions takes place and a kinetic model based on a direct and free radical reaction mechanism is proposed. Main influencing parameters to be known were: Direct ozone reaction rate constant, catalyst quantum yield, and hydroxyl radical scavengers. The first two take values of 0.5 M−1 s−1 and 5 × 10−4 mol·photon−1, respectively, while a fraction of TOC between 10% and 90% that changes with time was found to possess hydroxyl radical scavenger nature.

Electrochemical degradation of PAH compounds in process water: a kinetic study on model solutions and a proof of concept study on runoff water from harbour sediment purification

2010 ◽  
Vol 61 (8) ◽  
pp. 2043-2051 ◽  
Author(s):  
J. Muff ◽  
E. G. Søgaard
Keyword(s):  
Reaction Kinetics ◽  
Electrochemical Oxidation ◽  
Water Oxidation ◽  
Side Reaction ◽  
Product Formation ◽  
Polluted Water ◽  
Proof Of Concept ◽  
Runoff Water ◽  
Removal Rates ◽  
Concept Study

The present study has investigated the possibility to apply electrochemical oxidation in the treatment of polycyclic aromatic hydrocarbon (PAHs) pollutants in water. The reaction kinetics of naphthalene, fluoranthene, and pyrene oxidation have been studied in a batch recirculation experimental setup applying a commercial one-compartment cell of tubular design with Ti/Pt90-Ir10 anode. The rate of oxidation has been evaluated upon variations in current density, electrolyte composition and concentration. All three PAHs were degraded by direct anodic oxidation in 0.10 M Na2SO4 electrolyte, and the removal rates were significantly enhanced by a factor of two to six in 0.10 M NaCl due to contribution from the indirect hypochlorite oxidation. Second order reaction kinetics was observed for the degradation of naphthalene in all electrolytes whereas fluoranthene and pyrene followed first order kinetics. Decreased current densities from 200 to 15 mA cm−2 in the NaCl electrolyte also decreased the removal rates, but significantly enhanced the current efficiencies of the PAH oxidation, based on a defined current efficiency constant, kq. This observation is believed to be due to the suppression of the water oxidation side reaction at lower applied voltages. A proof of concept study in real polluted water demonstrated the applicability of the electrochemical oxidation technique for larger scale use, where especially the indirect chloride mediated oxidation approach was a promising technique. However, the risk and extent of by-product formation needs to be studied in greater detail.

scholarly journals Reaction kinetics and mechanisms of organosilicon fungicide flusilazole with sulfate and hydroxyl radicals

Chemosphere ◽  
2018 ◽  
Vol 190 ◽  
pp. 327-336 ◽  
Author(s):  
D. Fabio Mercado ◽  
Larisa L.B. Bracco ◽  
Antonio Arques ◽  
Mónica C. Gonzalez ◽  
Paula Caregnato
Keyword(s):  
Reaction Kinetics ◽  
Hydroxyl Radicals
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