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

2001 ◽  
Vol 44 (5) ◽  
pp. 15-15 ◽  
Author(s):  
J. Yoon ◽  
Y. Lee ◽  
S. Kim
Keyword(s):  
Landfill Leachate ◽  
Fenton Reaction ◽  
Reaction Pathway ◽  
Oxidation Products ◽  
Ferrous Ion ◽  
Oh Radicals ◽  
Effective Manner ◽  
Short Period ◽  
High Concentrations ◽  
Fenton System

Fenton reaction has been often used to treat industrial wastewater or landfill leachate. However, most mechanistic research into the Fenton reaction has been confined to low concentration conditions (usually the concentration of iron is less than 1 mM). These conditions are removed from the circumstances of real application. This is especially true in the treatment of landfill leachate in Korea. Therefore, we investigated the characteristics of the Fenton system using high concentrations of iron (mostly [Fe2+] = 1∼10 mM, [H2O2] = 5 mM, [Organic (t-BuOH or methanol)] = 0 or 30 mM) and interpreted the results from the known reaction mechanisms of the Fenton system. As a result, the use of high ferrous ion [≥1 mM) is believed to be appropriate for producing large quantities of OH• within a short period of time, causing fast consumption of hydrogen peroxide. However, OH• scavenging by the ferrous ion, the changes of oxidation products due to the oxygen depleted conditions, and the precipitation effect of ferric ion must be considered for the successful application of Fenton reaction. On the other hand, in low ferrous ion (<1 mM), it is important to utilize the redox cycles of iron in an effective manner.

Mechanistic and Kinetic Study of Atmospheric Oxidation of Chlordane Initiated by OH Radicals

2019 ◽  
Vol 16 (8) ◽  
pp. 647-655
Author(s):  
Zhezheng Ding ◽  
Yayi Yi ◽  
Fei Xu ◽  
Qingzhu Zhang ◽  
Xiaoli Xu ◽  
...  
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Geometrical Structures ◽  
Elementary Reactions ◽  
Atmospheric Fate ◽  
High Concentrations

Chlordane, one of the extremely hazardous Persistent Organic Pollutants (POPs), was widely used as pesticides all over the world and its residues have been detected at high concentrations in many areas. As a species of Semi-Volatile Organic Compounds (SVOCs), chlordane exists mainly in the atmosphere where it can be migrated and transformed. Due to the carcinogenic and mutagenic properties, understanding its atmospheric fate is of great significance. In the present work, the oxidation mechanism of chlordane initiated by OH radicals under the atmospheric conditions was investigated by using Density Functional Theory (DFT). The geometrical structures were optimized at the M06- 2X/6-311+g(d,p) level and single-point energies were calculated at the M06-2X/6-311+g(3df,2p) level. The relevant rate constants of the key elementary reactions were calculated by using Rice-Ramsperger- Kassel-Marcus (RRKM) theory at 298 K and 1 atm. All of the energetically favorable pathways were discussed in detail, and theoretical results showed that the oxidation products are dichlorochlordene, hydroxychlrodane, cycloketone and dichloracyl. Combined with available experimental observation, this study can, therefore, help to clarify the atmospheric fate of chlordane.

scholarly journals Spin trapping studies of essential oils in lipid systems

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 461-468 ◽  
Author(s):  
Katerina Makarova ◽  
Kinga Drązikowska ◽  
Beata Suska ◽  
Katarzyna Zawada ◽  
Iwona Wawer
Keyword(s):  
Essential Oils ◽  
Fenton Reaction ◽  
Spin Trap ◽  
Spin Trapping ◽  
Oh Radicals ◽  
Bath Salts ◽  
Radical Adduct ◽  
Hyperfine Splittings ◽  
Skin Care Products ◽  
Fenton System

Abstract In the present work, we report the results of a spin trapping ESR study of four essential oils widely used for skin care products such as creams and bath salts. The studied essential oils are Rosmarini aetheroleum (rosemary), Menthae piperitae aetheroleum (mint), Lavandulae aetheroleum (lavender), and Thymi aetheroleum (thyme). Fenton reaction in the presence of ethanol was used to generate free radicals. The N-tert-butyl-α-phenylnitrone (PBN) was used as a spin trap. In the Fenton reaction, the rosemary oil had the lowest effect on radical adduct formation as compared to the reference Fenton system. Since essential oils are known to be lipid soluble, we also conducted studies of essential oils in Fenton reaction in the presence of lipids. Two model lipids were used, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). The obtained results suggested that in the presence of DOPC lipids, the •OH and PBN/•CHCH3(OH) radicals are formed in both phases, that is, water and lipids, and all the studied essential oils affected the Fenton reaction in a similar way. Whereas, in the DPPC system, the additional type of PBN/X (aN = 16.1 G, aH = 2.9 G) radical adduct was generated. DFT calculations of hyperfine splittings were performed at B3LYP/6-311+G(d,p)/EPR-II level of theory for the set of c-centered PBN adducts in order to identify PBN/X radical.

Degradation of p-hydroxyphenylacetic acid by photoassisted Fenton reaction

2001 ◽  
Vol 44 (5) ◽  
pp. 31-38 ◽  
Author(s):  
J.L. Acero ◽  
F.J. Benítez ◽  
F.J. Real ◽  
A.I. Leal
Keyword(s):  
Fenton Reaction ◽  
Advanced Oxidation Processes ◽  
Radical Reaction ◽  
Industrial Plant ◽  
Oh Radicals ◽  
Oxidation Processes ◽  
Fenton’S Reaction ◽  
Optimum Ph ◽  
Hydroxyphenylacetic Acid ◽  
Fenton System

The chemical decomposition of p-hydroxyphenylacetic acid, a phenolic pollutant present in agro-industrial plant effluents, has been investigated by means of the Fenton's reaction and the photoassisted Fenton's reaction, the so-called photo-Fenton system. The degradation levels achieved have been compared to those obtained by applying other Advanced Oxidation Processes, such as the combination UV/H2O2. The optimum pH to carry out the decomposition of this organic compound by either Fenton or photo-Fenton systems was found to be pH = 3. The presence of buffers such as phosphate impedes these processes due to the formation of ferric complexes. A reaction mechanism, which allows calculating the contribution of the radical reaction to the global process, has been proposed. According to this mechanism, the dominant way of degradation of p-hydroxyphenylacetic acid is through its reaction with the OH radicals originated in the photolysis of H2O2 and, especially, in the Fenton's reaction.

scholarly journals Large contribution to secondary organic aerosol from isoprene cloud chemistry

2021 ◽  
Vol 7 (13) ◽  
pp. eabe2952
Author(s):  
Houssni Lamkaddam ◽  
Josef Dommen ◽  
Ananth Ranjithkumar ◽  
Hamish Gordon ◽  
Günther Wehrle ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Cloud Droplet ◽  
Organic Aerosol ◽  
Global Scale ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Large Contribution ◽  
Cloud Processing

Aerosols still present the largest uncertainty in estimating anthropogenic radiative forcing. Cloud processing is potentially important for secondary organic aerosol (SOA) formation, a major aerosol component: however, laboratory experiments fail to mimic this process under atmospherically relevant conditions. We developed a wetted-wall flow reactor to simulate aqueous-phase processing of isoprene oxidation products (iOP) in cloud droplets. We find that 50 to 70% (in moles) of iOP partition into the aqueous cloud phase, where they rapidly react with OH radicals, producing SOA with a molar yield of 0.45 after cloud droplet evaporation. Integrating our experimental results into a global model, we show that clouds effectively boost the amount of SOA. We conclude that, on a global scale, cloud processing of iOP produces 6.9 Tg of SOA per year or approximately 20% of the total biogenic SOA burden and is the main source of SOA in the mid-troposphere (4 to 6 km).

scholarly journals Enhancement of Iron-Based Photo-Driven Processes by the Presence of Catechol Moieties

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 372
Author(s):  
Javier Moreno-Andrés ◽  
Iván Vallés ◽  
Paula García-Negueroles ◽  
Lucas Santos-Juanes ◽  
Antonio Arques
Keyword(s):  
Fenton Reaction ◽  
Advanced Oxidation Processes ◽  
Salt Water ◽  
Degradation Process ◽  
Contaminants Of Emerging Concern ◽  
Low Salt ◽  
Aquaculture Industry ◽  
Iron Based ◽  
Ph Range ◽  
Fenton System

Photo-induced Advanced Oxidation Processes (AOPs) using H2O2 or S2O82− as radical precursors were assessed for the abatement of six different contaminants of emerging concern (CECs). In order to increase the efficiency of these AOPs at a wider pH range, the catechol organic functional compound was studied as a potential assistant in photo-driven iron-based processes. Different salinity regimes were also studied (in terms of Cl− concentration), namely low salt water (1 g·L−1) or a salt–water (30 g·L−1) matrix. Results obtained revealed that the presence of catechol could efficiently assist the photo-Fenton system and partly promote the photo-induced S2O82− system, which was highly dependent on salinity. Regarding the behavior of individual CECs, the photo-Fenton reaction was able to enhance the degradation of all six CECs, meanwhile the S2O82−-based process showed a moderate enhancement for acetaminophen, amoxicillin or clofibric acid. Finally, a response-surface methodology was employed to determine the effect of pH and catechol concentration on the different photo-driven processes. Catechol was removed during the degradation process. According to the results obtained, the presence of catechol in organic macromolecules can bring some advantages in water treatment for either freshwater (wastewater) or seawater (maritime or aquaculture industry).

Naphthalimide Assemblies for Simultaneous Detection of Ferrous Ion and H 2 O 2 to Prevent Fenton Reaction

2021 ◽  
Vol 6 (7) ◽  
pp. 1692-1698
Author(s):  
Amrit Kaur ◽  
Mandeep Kaur ◽  
Vandana Bhalla ◽  
Manroop Singh ◽  
A.J.S. Bhanwer ◽  
...  
Keyword(s):  
Fenton Reaction ◽  
Simultaneous Detection ◽  
Ferrous Ion

An algal process treatment combined with the Fenton reaction for high concentrations of amoxicillin and cefradine

RSC Advances ◽  
2015 ◽  
Vol 5 (122) ◽  
pp. 100775-100782 ◽  
Author(s):  
Haitao Li ◽  
Yu Pan ◽  
Zhizhi Wang ◽  
Shan Chen ◽  
Ruixin Guo ◽  
...  
Keyword(s):  
Fenton Reaction ◽  
High Concentrations ◽  
Action Process ◽  
Combined Technique

The goal of the current study was to create a combined technique for the removal of two common antibiotics (amoxicillin and cefradine) using Fenton and an algal action process.

Scale-up and cost analysis of a photo-Fenton system for sanitary landfill leachate treatment

2016 ◽  
Vol 283 ◽  
pp. 76-88 ◽  
Author(s):  
Tânia F.C.V. Silva ◽  
Amélia Fonseca ◽  
Isabel Saraiva ◽  
Rui A.R. Boaventura ◽  
Vítor J.P. Vilar
Keyword(s):  
Cost Analysis ◽  
Landfill Leachate ◽  
Scale Up ◽  
Sanitary Landfill ◽  
Leachate Treatment ◽  
Fenton System ◽  
Sanitary Landfill Leachate

Investigating the NO-dependent photooxidation of limonene by OH and O3 using the atmosphere simulation chamber SAPHIR

2021 ◽  
Author(s):  
Yat Sing Pang ◽  
Martin Kaminski ◽  
Anna Novelli ◽  
Philip Carlsson ◽  
Ismail-Hakki Acir ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Reaction Pathways ◽  
Oh Radicals ◽  
Oh Radical ◽  
Simulation Experiments ◽  
Master Chemical Mechanism ◽  
Simulation Results ◽  
Atmosphere Simulation Chamber

<p>Limonene is the fourth-most abundant monoterpene in the atmosphere, which upon oxidation leads to the formation of secondary organic aerosol (SOA) and thereby influences climate and air quality.</p><p>In this study, the oxidation of limonene by OH at different atmospherically relevant NO and HO<sub>2</sub> levels (NO: 0.1 – 10 ppb; HO<sub>2</sub>: 20 ppt) was investigated in simulation experiments in the SAPHIR chamber at Forschungszentrum Jülich. The analysis focuses on comparing measured radical concentrations (RO<sub>2</sub>, HO<sub>2</sub>, OH) and OH reactivity (k<sub>OH</sub>) with modeled values calculated using the Master Chemical Mechanism (MCM) version 3.3.1.</p><p>At high and medium NO concentrations, RO<sub>2</sub> is expected to quickly react with NO. An HO<sub>2</sub> radical is produced during the process that can be converted back to an OH radical by another reaction with NO. Consistently, for experiments conducted at medium NO levels (~0.5 ppb, RO<sub>2</sub> lifetime ~10 s), simulated RO<sub>2</sub>, HO<sub>2</sub>, and OH agree with observations within the measurement uncertainties, if the OH reactivity of oxidation products is correctly described.</p><p>At lower NO concentrations, the regeneration of HO<sub>2</sub> in the RO<sub>2</sub> + NO reaction is slow and the reaction of RO<sub>2</sub> with HO<sub>2</sub> gains importance in forming peroxides. However, simulation results show a large discrepancy between calculated radical concentrations and measurements at low NO levels (<0.1 ppb, RO<sub>2</sub> lifetime ~ 100 s). Simulated RO<sub>2</sub> concentrations are found to be overestimated by a factor of three; simulated HO<sub>2</sub> concentrations are underestimated by 50 %; simulated OH concentrations are underestimated by about 35%, even if k<sub>OH</sub> is correctly described. This suggests that there could be additional RO<sub>2</sub> reaction pathways that regenerate HO<sub>2</sub> and OH radicals become important, but they are not taken into account in the MCM model.</p>

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