Degradation of atrazine in the electrochemical LED-UV/Cl2 system: The role of •OH and Cl•

2021 ◽  
Author(s):  
Ying Huang ◽  
Yangyang Li ◽  
Minghao Kong ◽  
Dionysios D. Dionysiou ◽  
Lecheng Lei
Keyword(s):  
Degradation Kinetics ◽  
Free Chlorine

In this study, electrochemically generated free chlorine (EC/Cl2) was activated by UV275nm irradiation to degrade atrazine, a commonly used herbicide, investigating the degradation kinetics and mechanisms. The potential at RuO2/IrO2-Ti...

Characteristics of p-chlorophenol degradation by Photo Fenton oxidation

2000 ◽  
Vol 42 (3-4) ◽  
pp. 219-224 ◽  
Author(s):  
J. Yoon ◽  
S. Kim ◽  
D.S. Lee ◽  
J. Huh
Keyword(s):  
Degradation Kinetics ◽  
Decomposition Kinetics ◽  
Fenton Oxidation ◽  
Oh Radical ◽  
Mercury Lamp ◽  
Batch Mode ◽  
Specific Objective ◽  
Initial Ph

This study investigated the characteristics of Photo Fenton oxidation in comparison with Fenton oxidation in dark environments. The specific objective was to provide an in-depth understanding as to how the presence of UV would effect the reaction and its efficiency as compared to the Dark Fenton Oxidation. All reactions were carried out in batch mode at an initial pH of 3.5, with H2O2 in excess and iron in catalytic concentrations. The medium pressure mercury lamp (320-400 nm) was used as a UV source. The role of UV in Photo Fenton Oxidation of p-chlorophenol was found to be manyfold as compared to Dark Fenton Oxidation. It included the expedition of ferric ion reduction and the photolysis of H2O2, which exerted a direct impact on the p-chlorophenol degradation kinetics by enhancing the production of OH radical. Also included in the role was alteration of the quantity (and potentially quality) of intermediates, which would lead to a change in the decomposition kinetics in an indirect manner. Therefore, it was concluded that the performance of Photo Fenton Oxidation as compared to Dark Fenton Oxidation could vary in complicated ways depending upon the characteristics of target compounds and their intermediates.

Control of disinfection and halogenated disinfection byproducts by the electrochemical process

2007 ◽  
Vol 55 (12) ◽  
pp. 213-219 ◽  
Author(s):  
Y.J. Jung ◽  
B.S. Oh ◽  
J.W. Kang ◽  
M.A. Page ◽  
M.J. Phillips ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Disinfection Byproducts ◽  
Electrochemical Process ◽  
Free Chlorine ◽  
Haloacetic Acids ◽  
Oh Radicals ◽  
Inactivation Kinetic ◽  
E Coli ◽  
Electrochemical Processes

The aim of this study was to investigate some aspects of the performance of electrochemical process as an alternative disinfection strategy, while minimising DBPs, for water purification. The study of electrochemical processes has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals (•OH), were also generated. The formation of mixed oxidants increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Using several microorganisms, such as E. coli and MS2 bacteriophage, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radicals, was investigated for enhancement of the inactivation rate. Additionally, the formation and reduction of DBPs was studied by monitoring the concentration of haloacetic acids (HAAs) during the process.

Reactivity of the Polyamide Membrane Monomer with Free Chlorine: Reaction Kinetics, Mechanisms, and the Role of Chloride

2019 ◽  
Vol 53 (14) ◽  
pp. 8167-8176 ◽  
Author(s):  
Kun Huang ◽  
Keith P. Reber ◽  
Michael D. Toomey ◽  
Holly Haflich ◽  
John A. Howarter ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Free Chlorine ◽  
Chlorine Reaction ◽  
Polyamide Membrane

scholarly journals The roles of bromide and precursor structures on DBP formation and species distribution

2006 ◽  
Vol 6 (4) ◽  
pp. 27-33 ◽  
Author(s):  
G.S. Wang ◽  
P.L. Huang
Keyword(s):  
Organic Matter ◽  
Organic Acids ◽  
Natural Organic Matter ◽  
Species Distribution ◽  
Ph Effect ◽  
Free Chlorine ◽  
Haloacetic Acids ◽  
Formation Potential ◽  
Trihalomethane Formation Potential

This study investigates the role of bromide and the structure of precursors in DBPs formation. Resorcinol (1,3-dihydroxylbenzene) and 2,4-pentadiol were used to represent the aromatic and aliphatic precursors. Laboratory prepared hydrophilic organic acids was used to simulate the mixtures of the aqueous natural organic matter. The results showed that about 60% of the bromide was transformed into HOBr and OBr− by chlorine when the chlorine dosages was high (5–20 mg/L of free chlorine). However, only 20% of bromide was transformed into HOBr and OBr− at low chlorine dosage (1 mg/L). Trihalomethane formation potential (THMFP) measurements showed that higher THMs formation was obtained at higher pH for 2,4-pentadiol, mainly due to the presence of the bromo-THMs. For resorcinol, however, no bromo-THMs are formed at either pH 7 or 9. For THMFP from hydrophilic organic acids, no apparent pH effect was observed. It is concluded that the higher THM formation at higher pH was mainly due to the formation of bromo-THMs from the aliphatic precursors. Similar trends are obtained in THMFP measurements for haloacetic acids formation potential (HAAFP).

scholarly journals Role of AT1G72910, AT1G72940, and ADR1-LIKE 2 in Plant Immunity under Nonsense-Mediated mRNA Decay-Compromised Conditions at Low Temperatures

2020 ◽  
Vol 21 (21) ◽  
pp. 7986
Author(s):  
Zeeshan Nasim ◽  
Muhammad Fahim ◽  
Katarzyna Gawarecka ◽  
Hendry Susila ◽  
Suhyun Jin ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Mrna Decay ◽  
Degradation Kinetics ◽  
Plant Immunity ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Stunted Growth ◽  
Nonsense Mediated Mrna Decay

Nonsense-mediated mRNA decay (NMD) removes aberrant transcripts to avoid the accumulation of truncated proteins. NMD regulates nucleotide-binding, leucine-rich repeat (NLR) genes to prevent autoimmunity; however, the function of a large number of NLRs still remains poorly understood. Here, we show that three NLR genes (AT1G72910, AT1G72940, and ADR1-LIKE 2) are important for NMD-mediated regulation of defense signaling at lower temperatures. At 16 °C, the NMD-compromised up-frameshift protein1 (upf1) upf3 mutants showed growth arrest that can be rescued by the artificial miRNA-mediated knockdown of the three NLR genes. mRNA levels of these NLRs are induced by Pseudomonas syringae inoculation and exogenous SA treatment. Mutations in AT1G72910, AT1G72940, and ADR1-LIKE 2 genes resulted in increased susceptibility to Pseudomonas syringae, whereas their overexpression resulted in severely stunted growth, which was dependent on basal disease resistance genes. The NMD-deficient upf1 upf3 mutants accumulated higher levels of NMD signature-containing transcripts from these NLR genes at 16 °C. Furthermore, mRNA degradation kinetics showed that these NMD signature-containing transcripts were more stable in upf1 upf3 mutants. Based on these findings, we propose that AT1G72910, AT1G72940, and ADR1-LIKE 2 are directly regulated by NMD in a temperature-dependent manner and play an important role in modulating plant immunity at lower temperatures.

scholarly journals EFEITO DO ÓLEO DE SEMENTE DE UVA SOBRE O POLIPROPILENO (PP) RECICLADO. PARTE I: CINÉTICA DE DEGRADAÇÃO

2018 ◽  
Vol 4 (1) ◽  
pp. 0049-0058 ◽  
Author(s):  
Helson Moreira Da Costa ◽  
Valéria Dutra Ramos ◽  
Leonardo Luis Esteves
Keyword(s):  
Seed Oil ◽  
Degradation Kinetics ◽  
Oxidative Degradation ◽  
Melt Flow Index ◽  
Kinetic Mechanism ◽  
Flow Index ◽  
Recycled Polypropylene ◽  
Thermogravimetric Data ◽  
Thermo Oxidative Degradation

O óleo de semente de uva (OSV) foi incorporado ao polipropileno (PP) reciclado em 4% em massa. Uma série de oito extrusões consecutivas foi realizada e dados sobre o índice de fluidez (MFI) foram obtidos. A análise termogravimétrica (TGA/DTG) também foi conduzida e a cinética de degradação termo-oxidativa foi determinada. Os resultados de MFI alcançados permitiram concluir que o OSV apresenta um papel de “plastificante externo” e/ou lubrificante. Por sua vez, os dados termogravimétricos mostraram que o OSV atua como antioxidante para o PP reciclado. Após oito extrusões consecutivas, a amostra PP rec./OSV apresentou maiores valores de TM, Tendset e t1/2 do que a amostra de PP rec. Além disso, seguindo o procedimento de análise cinética descrito por Esteves et al. (2017), foi verificado que o OSV permitiu que maiores valores de energia de ativação, durante o processo termo-oxidativo, fossem alcançados e que um mecanismo cinético hipotético, diferente daquele do PP rec., também pudesse ser encontrado.Grape seed oil (OSU) was incorporated into recycled polypropylene (PP) at 4% by weight. A series of eight consecutive extrusions was performed and melt flow index (MFI) data were obtained. Thermogravimetric analysis (TGA/DTG) was also conducted and thermo-oxidative degradation kinetics was determined. MFI results allowed to conclude that OSU presents a role of "external plasticizer" and/or lubricant. In turn, thermogravimetric data showed that OSU acts as an antioxidant for recycled PP. After eight consecutive extrusions, PP rec./OSU sample presented higher TM, Tendset and t1/2 values ​​than rec PP sample. In addition, following the kinetic analysis procedure described in the literature, it was verified that OSU allowed higher values ​​of activation energy, during thermo-oxidative process, were achieved and that a hypothetical kinetic mechanism, different from that of the PP rec., was also found.

scholarly journals Study on Solubilization and Stabilization of Eight Flavonoids by 17 Chinese Herbal Polysaccharides

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xuexiao Cao ◽  
Lei Wang ◽  
Meiqi Liu ◽  
Xiaoliang Ren ◽  
Tingting Han ◽  
...  
Keyword(s):  
High Performance ◽  
Degradation Kinetics ◽  
Biological Activities ◽  
Phase Solubility ◽  
Active Components ◽  
Buffer Solution ◽  
Chinese Medicines ◽  
Acceleration Method ◽  
The Stability

Flavonoids are important active components of traditional Chinese medicines (TCMs) because of their many biological activities. We studied the interaction between 17 polysaccharides and eight flavonoids via high-performance liquid chromatography (HPLC) and the effect of the interactions on the solubility and stability of the flavonoids. The effect of the polysaccharides on the solubility of flavonoids was analyzed by statistical methods and showed significant solubility improvements. The constant temperature acceleration method (90°C/pH 9 buffer solution) was used to measure the degradation kinetics and half-life of flavonoids with and without polysaccharides. All the polysaccharides displayed a stabilizing effect on all eight flavonoids. The stabilizing effects varied in the order: quercetin, baicalein > baicalin > galuteolin > daidzin > rutin > luteolin > daidzien. The phase-solubility method was applied to quercetin and baicalein to study the mechanism of action of the polysaccharides. It appeared that the two flavonoids could form 1 : 1 inclusion complexes with polysaccharides, which may be one of the factors increasing solubility and stability. These findings increase our understanding of the role of endogenous polysaccharides in TCM in improving the stability and bioavailability of bioactive flavonoids.

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