scholarly journals Synergistic Degradation of Chloramphenicol by an Ultrasound-Enhanced Fenton-like Sponge Iron System

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3561
Author(s):  
Xia Meng ◽  
Zhongming Liu ◽  
Shoujuan Wang ◽  
Fangong Kong
Keyword(s):  
Degradation Rate ◽  
Degradation Products ◽  
Iron Concentration ◽  
Sponge Iron ◽  
Degradation Efficiency ◽  
Gas Chromatography Mass Spectrometry ◽  
Oh Radicals ◽  
Surface Method ◽  
Synergistic Degradation ◽  
The Impact

In this study, an ultrasound Fenton-like sponge iron system was used to enhance the degradation efficiency for chloramphenicol (CAP). Three single-factor experiments of reaction pH, hydrogen peroxide (H2O2) concentration, and sponge iron (Fe) concentration were used to explore the impact on CAP degradation efficiency. The response surface method revealed the interactions between various factors. The degradation efficiency for CAP was as high as 99.97% at pH = 3, 3.19 mmol/L H2O2, and a sponge iron concentration of 2.26 g/L. The degradation rate for CAP was significantly reduced upon the addition of some inorganic salts, mainly due to the quenching of OH radicals. Gram-negative (G(−)) Escherichia coli and Gram-positive (G(+)) Staphylococcus aureus were used to evaluate the changes in the antibacterial activity of CAP. Finally, gas chromatography/mass spectrometry (GC-MS) was used to identify the degradation products and the degradation path for the products was proposed based on the detected products.

Detection of Fourth Generation Synthetic Halocarbons in the Upper Troposphere

2021 ◽  
Author(s):  
Tanja Schuck ◽  
Katharina Meixner ◽  
Peter van Velthoven ◽  
Simon O’Doherty ◽  
Martin Vollmer ◽  
...  
Keyword(s):  
Degradation Products ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Gas Chromatography Mass Spectrometry ◽  
Fourth Generation ◽  
Oh Radicals ◽  
Sample Collection ◽  
Upper Troposphere ◽  
Wide Range ◽  
Air Sample

<p>Synthetic halocarbons are used for a wide range of applications, for example air conditioning or foam blowing. Many of them are long-lived greenhouse gases contributing to climate change and, in addition, may contribute to stratospheric ozone depletion if containing chlorine or bromine. Therefore, their production and use are regulated by the Montreal Protocol and its amendments. These long-lived halocarbons are increasingly replaced by a fourth generation of unsaturated short-lived halocarbons, the hydrochlorofluoroolefines (HCFOs) and hydrofluoroolefines (HFOs). The main removal process of these compounds in the atmosphere is reaction with OH radicals, and their average lifetimes are of the order of up to a few tens of days.</p><p>As part of the IAGOS-CARIBIC instrument package we operate an automated air sample collection system during regular flights in the upper troposphere and lowermost stratosphere. At altitudes around 10-12 km, samples are collected in stainless steel and glass flasks at predefined times. Post-flight laboratory analyses include gas chromatography - mass spectrometry measurements of a wide range of halocarbons. The short-lived compounds HFO-1234ze(E) and HCFO-1233zd(E) were detected in a small number of samples, indicating that these compounds are sufficiently long lived for transport into the upper troposphere. There were not found in stratospheric samples.</p><p>At this altitude, low abundance of OH and low temperatures may slow down chemical decay, and tracer lifetimes may increase significantly. Based on average temperatures and OH abundance, we estimate local lifetimes of HFO-1234ze(E) and HCFO-1233zd(E)  in the mid-latitudes of up to 75 days and 200 days, respectively. Short-lived H(C)FOs reaching the upper troposphere could thus be transported over large distances and their degradation products may be deposited  far from their emission sources.</p>

scholarly journals Evaluation of the daytime tropospheric loss of 2-methylbutanal

2021 ◽  
Author(s):  
María Asensio ◽  
María Antiñolo ◽  
Sergio Blázquez ◽  
José Albaladejo ◽  
Elena Jiménez
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gaseous Products ◽  
Flight Mass Spectrometry ◽  
Atmospheric Degradation ◽  
The Impact

Abstract. Saturated aldehydes, e.g. 2-methylbutanal (2MB, CH3CH2CH(CH3)C(O)H), are emitted into the atmosphere by several biogenic sources. The first step in the daytime atmospheric degradation of 2MB involves gas-phase reactions initiated by hydroxyl (OH) radicals, chlorine (Cl) atoms and/or sunlight. In this work, we report the rate coefficients for the gas-phase reaction of 2MB with OH (kOH) and Cl (kCl) together with the photolysis rate coefficient (J) in the ultraviolet solar actinic region in Valencia (Spain) at different times of the day. The temperature dependence of kOH was described in the 263–353 K range by the following Arrhenius expression: kOH(T)=(8.88±0.41)×10-12 exp[(331±14)/T] cm3 molecule-1 s-1. At 298 K, the reported kOH and kCl are (2.68±0.07)×10-11 cm3 molecule-1 s-1 and (2.16±0.16)×10-11 cm3 molecule-1 s-1. Identification and quantification of the gaseous products of the Cl-reaction and those from the photodissociation of 2MB were carried out in a smog chamber by different techniques (Fourier transform infrared spectroscopy, proton transfer time-of-flight mass spectrometry, and gas chromatography coupled to mass spectrometry). The formation and size distribution of secondary organic aerosols formed in the Cl-reaction was monitored by a fast mobility particle sizer spectrometer. A discussion on the relative importance of the first step in the daytime atmospheric degradation of 2MB is presented together with the impact of the degradation products in marine atmospheres.

Environmental Friendly Degradation of Atrazine by Ozone and Identification of Main Degradation Products

2014 ◽  
Vol 1001 ◽  
pp. 52-57
Author(s):  
Marián Šudý ◽  
Karol Balog ◽  
Maroš Soldán
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Degradation Products ◽  
Degradation Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Oh Radicals ◽  
Environmental Friendly ◽  
Chromatography Mass Spectrometry ◽  
Atrazine Degradation

The present study investigates the degradation of atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-s-triazine) by ozone and OH radicals during ozonization with the identification of the main degradation products after ozonation. The identification of main degradation products during atrazine degradation process was conducted by gas chromatography–mass spectrometry (GC–MS).

scholarly journals Exploration on the Enhancement of Detoxification Ability of Zearalenone and Its Degradation Products of Aspergillus niger FS10 under Directional Stress of Zearalenone

Toxins ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 720
Author(s):  
Jian Ji ◽  
Jian Yu ◽  
Yang Yang ◽  
Xiao Yuan ◽  
Jia Yang ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Metabolic Profile ◽  
Degradation Rate ◽  
Degradation Products ◽  
Degradation Efficiency ◽  
Environmental Friendly ◽  
Wide Range ◽  
Before And After ◽  
Low Toxicity ◽  
Metabolomics Analysis

Zearalenone (ZEN) is one of the most common mycotoxin contaminants in food. For food safety, an efficient and environmental-friendly approach to ZEN degradation is significant. In this study, an Aspergillus niger strain, FS10, was stimulated with 1.0 μg/mL ZEN for 24 h, repeating 5 times to obtain a stressed strain, Zearalenone-Stressed-FS10 (ZEN-S-FS10), with high degradation efficiency. The results show that the degradation rate of ZEN-S-FS10 to ZEN can be stabilized above 95%. Through metabolomics analysis of the metabolome difference of FS10 before and after ZEN stimulation, it was found that the change of metabolic profile may be the main reason for the increase in the degradation rate of ZEN. The optimization results of degradation conditions of ZEN-S-FS10 show that the degradation efficiency is the highest with a concentration of 104 CFU/mL and a period of 28 h. Finally, we analyzed the degradation products by UPLC-q-TOF, which shows that ZEN was degraded into two low-toxicity products: C18H22O8S (Zearalenone 4-sulfate) and C18H22O5 ((E)-Zearalenone). This provides a wide range of possibilities for the industrial application of this strain.

scholarly journals Abatement of trichloroethylene using DBD plasma

2014 ◽  
Vol 32 ◽  
pp. 1460344
Author(s):  
M. Vesali-Naseh ◽  
S. Xu ◽  
L. Xu ◽  
A. Khodadadi ◽  
Y. Mortazavi ◽  
...  
Keyword(s):  
Discharge Plasma ◽  
Barrier Discharge ◽  
Degradation Products ◽  
Gas Chromatography Mass Spectrometry ◽  
Oh Radicals ◽  
Dielectric Barrier Discharge Plasma ◽  
Dbd Plasma ◽  
Optimum Energy ◽  
Barrier Discharge Plasma ◽  
Zero Order Reaction

Dielectric barrier discharge plasma was used to oxidize trichloroethylene (TCE) in 21% of O 2 in carriers of N 2 and He . The degradation products of TCE were analyzed using gas chromatography mass spectrometry. TCE was decomposed completely at optimum energy density of 260 and 300 J/l for He and N 2, respectively and its conversion followed zero order reaction. The TCE removal efficiency is decreased in humid air due to interception of reactive intermediates by OH radicals.

scholarly journals Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16

2021 ◽  
Vol 22 (17) ◽  
pp. 9242
Author(s):  
Yuxin Guo ◽  
Yaohua Huang ◽  
Shimei Pang ◽  
Tianhao Zhou ◽  
Ziqiu Lin ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
High Performance ◽  
Degradation Rate ◽  
Degradation Products ◽  
Living System ◽  
Gas Chromatography Mass Spectrometry ◽  
Synthetic Pyrethroids ◽  
Half Saturation Constant ◽  
Important Concern ◽  
Specific Degradation

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L−1 of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20–40 °C, pH 5–9, and initial tetramethrin 25–800 mg·L−1. The maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were determined to be 0.4561 day−1, 7.3 mg·L−1, and 75.2 mg·L−1, respectively. The Box–Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography–mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg−1) with strain A16 (1.0 × 107 cells g−1 of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.

THE IMPACT OF WIND CONDITIONS ON THE LEVELS OF TOTAL IRON CONTENT IN THE SEA OF AZOV

2017 ◽  
Author(s):  
Yuri Fedorov ◽  
Yuri Fedorov ◽  
Irina Dotsenko ◽  
Irina Dotsenko ◽  
Leonid Dmitrik ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Iron Content ◽  
Iron Concentration ◽  
Total Iron ◽  
Sea Of Azov ◽  
Open Area ◽  
The Sea Of Azov ◽  
Dissolved Iron ◽  
The Impact ◽  
Taganrog Bay

The distribution and behavior of certain of trace elements in sea water is greatly affected by both physical, chemical and hydrometeorological conditions that are showed in the scientific works of prof. Yu.A. Fedorov with coauthors (1999-2015). Due to the shallow waters last factor is one of the dominant, during the different wind situation changes significantly the dynamics of water masses and interaction in the system “water – suspended matter – bottom sediments”.Therefore, the study of the behavior of the total iron in the water of the sea at different wind situation is relevant. The content of dissolved iron forms migration in The Sea of Azov water (open area) varies from 0.017 to 0.21 mg /dm3 (mean 0.053 mg /dm3) and in Taganrog Bay from 0.035 to 0.58 mg /dm3 (mean 0.11 mg /dm3) and it is not depending on weather conditions.The reduction in the overall iron concentration in the direction of the Taganrog Bay → The Sea of Azov (open area) is observed on average more than twice. The dissolved iron content exceeding TLV levels and their frequency of occurrence in the estuary, respectively, were higher compared with The Sea of Azov (open area).There is an increase in the overall iron concentration in the water of the Azov Sea on average 1.5 times during the storm conditions, due to the destruction of the structure of the upper layer and resuspension of bottom sediments, intensifying the transition of iron compounds in the solution.

scholarly journals High MB Solution Degradation Efficiency of FeSiBZr Amorphous Ribbon with Surface Tunnels

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3694 ◽  
Author(s):  
Qi Chen ◽  
Zhicheng Yan ◽  
Hao Zhang ◽  
Lai-Chang Zhang ◽  
Haijian Ma ◽  
...  
Keyword(s):  
Specific Surface ◽  
Porous Structure ◽  
Surface Area ◽  
Free Volume ◽  
Specific Surface Area ◽  
Degradation Rate ◽  
High Efficiency ◽  
Amorphous Ribbon ◽  
Degradation Efficiency ◽  
Characteristic Distance

The as spun amorphous (Fe78Si9B13)99.5Zr0.5 (Zr0.5) and (Fe78Si9B13)99Zr1 (Zr1) ribbons having a Fenton-like reaction are proved to bear a good degradation performance in organic dye wastewater treatment for the first time by evaluating their degradation efficiency in methylene blue (MB) solution. Compared to the widely studied (Fe78Si9B13)100Zr0 (Zr0) amorphous ribbon for degradation, with increasing cZr (Zr atomic content), the as-spun Zr0, Zr0.5 and Zr1 amorphous ribbons have gradually increased degradation rate of MB solution. According to δc (characteristic distance) of as-spun Zr0, Zr0.5 and Zr1 ribbons, the free volume in Zr1 ribbon is higher Zr0 and Zr0.5 ribbons. In the reaction process, the Zr1 ribbon surface formed the 3D nano-porous structure with specific surface area higher than the cotton floc structure formed by Zr0 ribbon and coarse porous structure formed by Zr0.5 ribbon. The Zr1 ribbon’s high free volume and high specific surface area make its degradation rate of MB solution higher than that of Zr0 and Zr0.5 ribbons. This work not only provides a new method to remedying the organic dyes wastewater with high efficiency and low-cost, but also improves an application prospect of Fe-based glassy alloys.

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