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International Journal of Environmental... Mar 2023NO is a greenhouse gas and a candidate oxidant. Volatile organic pollutants (VOCs) have caused great harm to the atmospheric ecological environment. Developing the...
NO is a greenhouse gas and a candidate oxidant. Volatile organic pollutants (VOCs) have caused great harm to the atmospheric ecological environment. Developing the technique utilizing NO as the oxidant to oxidize VOCs to realize the collaborative purification has significant importance and practical value for NO emission control and VOC abatement. Therefore, the study of NO catalytic oxidation of tert-butanol based on zeolite catalysts was carried out. A series of molecular sieves, including FER, MOR, ZSM-5, Y, and BEA, were selected as the catalyst objects, and the 1.5% wt Fe and Co were, respectively, loaded on the zeolite catalysts via the impregnation method. It was found that the catalytic performance of BEA was the best among the molecular sieves. Comparing the catalytic performance of Fe-BEA under different load gradients (0.25~2%), it was found that 1.5% Fe-BEA possessed the best catalytic activity. A series of characterization methods showed that Fe content in 1.5% Fe-BEA was the highest, and more active sites formed to promote the catalytic reaction. The α-O in the reaction eventually oxidized tert-butanol to CO over the active site. The Co mainly existed in the form of Co cations over Co-BEA samples; the 2% Co-BEA possessing higher amounts of Co exhibited the highest activity among the prepared Co-BEA samples.
Topics: tert-Butyl Alcohol; Zeolites; Oxidants; Oxidation-Reduction
PubMed: 36981811
DOI: 10.3390/ijerph20064902 -
Archives of Biochemistry and Biophysics Dec 2017Free and ester forms of unsaturated fatty acids and cholesterol are oxidized in vivo by multiple oxidants to give diverse products. Some lipid oxidation is mediated by...
Isomer distribution of hydroxyoctadecadienoates (HODE) and hydroxyeicosatetraenoates (HETE) produced in the plasma oxidation mediated by peroxyl radical, peroxynitrite, hypochlorite, 15-lipoxygenase, and singlet oxygen.
Free and ester forms of unsaturated fatty acids and cholesterol are oxidized in vivo by multiple oxidants to give diverse products. Some lipid oxidation is mediated by enzymes to selectively give specific products, while others proceed randomly to produce mixtures of many kinds of regioisomers and stereoisomers. The efficacy of antioxidants against lipid oxidation depends on the nature of the oxidants and therefore the identification of oxidant is important for understanding the roles and effects of lipid oxidation and antioxidants in vivo. In the present study, the isomer distribution of hydro(pero)xyoctadecadienoates (H(p)ODEs) and hydro(pero)xyeicosatetraenoates (H(p)ETEs), the most abundant lipid oxidation products found in human plasma, produced in the oxidation of plasma by peroxyl radicals, peroxynitrite, hypochlorite, 15-lipoxygenase, and singlet oxygen were examined. It was shown that 9- and 13-(E,E)-HODEs, 13(S)-(Z,E)-HODE, and 10- and 12-(Z,E)-HODEs were specific lipid oxidation products by free radical, 15-lipoxygenase, and singlet oxygen, respectively. The isomer distribution of HODEs produced by peroxynitrite was similar to that by peroxyl radical, suggesting that the peroxynitrite mediated lipid oxidation proceeds by free radical mechanisms. The production of HODEs and HETEs by hypochlorite was very small. HODEs may be a better biomarker than HETEs since linoleates are oxidized by simpler mechanisms than arachidonates and all the HODEs isomers can be quantified more easily. These products may be used as specific biomarkers for the identification of responsible oxidants and for the assessment of oxidant-specific lipid oxidation levels and effects of antioxidants in vivo.
Topics: Animals; Arachidonate 15-Lipoxygenase; Fatty Acids, Unsaturated; Hydroxyeicosatetraenoic Acids; Hypochlorous Acid; Mice; Oxidants; Oxidation-Reduction; Peroxides; Peroxynitrous Acid; Plasma; Singlet Oxygen; Stereoisomerism
PubMed: 29097313
DOI: 10.1016/j.abb.2017.10.023 -
Environmental Research Sep 2023In this study, the relative residual UV absorbance (UV) and/or electron donating capacity (EDC) was investigated as a surrogate parameter to evaluate the abatement of...
In this study, the relative residual UV absorbance (UV) and/or electron donating capacity (EDC) was investigated as a surrogate parameter to evaluate the abatement of micropollutants during the Fe(II)/PMS and Mn(II)/NTA/PMS processes. In the Fe(II)/PMS process, due to the generation of SO and •OH at acidic pH, UV and EDC abatement was greater at pH 5. In the Mn(II)/NTA/PMS process, UV abatement was greater at pH 7 and 9, while EDC abatement was greater at pH 5 and 7. This was attributed to the fact that MnO was formed at alkaline pH to remove UV by coagulation, and manganese intermediates (Mn(V)) were formed at acidic pH to remove EDC via electron transfer. Due to the strong oxidation capacity of SO, •OH and Mn(V), the abatement of micropollutants increased with increasing dosages of oxidant in different waters in both processes. In the Fe(II)/PMS and Mn(II)/NTA/PMS processes, except for nitrobenzene (∼23% and 40%, respectively), the removal of other micropollutants was greater than 70% when the oxidant dosages were greater in different waters. The linear relationship between the relative residual UV, EDC and the removal of micropollutants was established in different waters, showing a one-phase or two-phase linear relationship. The differences of the slopes for one-phase linear correlation in the Fe(II)/PMS process (micropollutant-UV: 0.36-2.89, micropollutant-EDC: 0.26-1.75) were less than that in the Mn(II)/NTA/PMS process (micropollutant-UV: 0.40-13.16, micropollutant-EDC: 0.51-8.39). Overall, these results suggest that the relative residual UV and EDC could truly reflect the removal of micropollutants during the Fe(II)/PMS and Mn(II)/NTA/PMS processes.
Topics: Electrons; Manganese Compounds; Water Pollutants, Chemical; Oxides; Oxidation-Reduction; Oxidants; Ferrous Compounds
PubMed: 37276973
DOI: 10.1016/j.envres.2023.116253 -
Antioxidants & Redox Signaling May 2023The MarR/DUF24-family QsrR and YodB repressors control quinone detoxification pathways in and . In , the QsrR regulon also confers resistance to antimicrobial...
The MarR/DUF24-family QsrR and YodB repressors control quinone detoxification pathways in and . In , the QsrR regulon also confers resistance to antimicrobial compounds with quinone-like elements, such as rifampicin, ciprofloxacin, and pyocyanin. Although QsrR was shown to be inhibited by thiol--alkylation of its conserved Cys4 residue by 1,4-benzoquinone, YodB senses quinones and diamide by the formation of reversible intermolecular disulfides. In this study, we aimed at further investigating the redox-regulation of QsrR and the role of its Cys4, Cys29, and Cys32 residues under quinone and oxidative stress in . The QsrR regulon was strongly induced by quinones and oxidants, such as diamide, allicin, hypochlorous acid (HOCl), and AGXX in . Transcriptional induction of by quinones and oxidants required Cys4 and either Cys29' or Cys32' of QsrR for redox sensing . DNA-binding assays revealed that QsrR is reversibly inactivated by quinones and oxidants, depending on Cys4. Using mass spectrometry, QsrR was shown to sense diamide by an intermolecular thiol-disulfide switch, involving Cys4 and Cys29' of opposing subunits . In contrast, allicin caused -thioallylation of all three Cys residues in QsrR, leading to its dissociation from the operator sequence. Further, the QsrR regulon confers resistance against quinones and oxidants, depending on Cys4 and either Cys29' or Cys32'. QsrR was characterized as a two-Cys-type redox-sensing regulator, which senses the oxidative mode of quinones and strong oxidants, such as diamide, HOCl, and the antimicrobial compound allicin different thiol switch mechanisms.
Topics: Sulfhydryl Compounds; Quinones; Staphylococcus aureus; Oxidants; Diamide; Oxidation-Reduction; Hypochlorous Acid; Bacterial Proteins
PubMed: 36242097
DOI: 10.1089/ars.2022.0090 -
Experimental Gerontology Sep 2022As organisms age, cellular function declines in a time-dependent manner. Oxidative stress induced by reactive oxygen species damages cellular machinery and contributes...
As organisms age, cellular function declines in a time-dependent manner. Oxidative stress induced by reactive oxygen species damages cellular machinery and contributes to senescence which narrows the homeostatic window needed to maintain function and survive stress. Sex differences in longevity are apparent in many species and may be related to sex-specific homeostatic responses. Here we use the emerging aging model system Tigriopus californicus, the splashpool copepod, to estimate sex- and age-specific tolerances to two chemical oxidants, hydrogen peroxide and paraquat. Sex-specific tolerance was estimated for both oxidants simultaneously for 15 age-classes. As animals aged, hydrogen peroxide tolerance decreased but paraquat tolerance increased. Also, we observed no sex difference for hydrogen peroxide tolerance, while females were more tolerant of paraquat. Our results demonstrate that oxidative stressors can have dramatically different sex and age effects in Tigriopus californicus. These findings underscore the challenges ahead in understanding relationships among oxidative stressors, sex, and aging.
Topics: Animals; Copepoda; Female; Hydrogen Peroxide; Male; Oxidants; Oxidative Stress; Paraquat
PubMed: 35750273
DOI: 10.1016/j.exger.2022.111871 -
Chemosphere Oct 2020With low potential to generate harmful by-products, peracetic acid (PAA) has drawn increasing attention as an alternative oxidant for disinfection and advanced oxidation...
With low potential to generate harmful by-products, peracetic acid (PAA) has drawn increasing attention as an alternative oxidant for disinfection and advanced oxidation processes in wastewater treatment. Commercial formulations contain significant concentrations of both PAA and HO in aqueous solutions and a robust method to distinctively quantify the two respective oxidants simultaneously is needed. This study aimed to improve the accuracy of employing methyl p-tolyl sulfide (MTS) and triphenylphosphine (TPP) as indicators for PAA and HO, respectively, under various environmental conditions, by the detection of the oxidation products of sulfoxide MTSO and phosphine oxide TPPO using HPLC-UV. To improve the analytical method, the reaction rates of MTS and TPP with PAA and HO, impact of pH on the detection, and matrix effects of real wastewater effluents and produce wash water were evaluated to minimize the interference of HO with PAA determination. The determined rate constants of PAA reaction with MTS (k=34.6±0.4Ms in 2/1 HO/acetonitrile (ACN) (v/v)) and HO reaction with TPP ( [Formula: see text] in 1/1 HO/ACN (v/v)) provided the fundamental guidance to optimize the method. Overall, a highly accurate and sensitive method for simultaneous quantification of PAA and HO (method quantification limit = 0.8 and 6.0 μM, respectively) is established and will be useful for various environmental samples with PAA and HO applications.
Topics: Chromatography, High Pressure Liquid; Disinfection; Hydrogen Peroxide; Oxidants; Oxidation-Reduction; Peracetic Acid; Wastewater; Water; Water Purification
PubMed: 32505952
DOI: 10.1016/j.chemosphere.2020.127229 -
Free Radical Biology & Medicine Aug 2020Selenium compounds have been identified as potential oxidant scavengers for biological applications due to the nucleophilicity of Se, and the ease of oxidation of the...
Selenium compounds have been identified as potential oxidant scavengers for biological applications due to the nucleophilicity of Se, and the ease of oxidation of the selenium centre. Previous studies have reported apparent second order rate constants for a number of oxidants (e.g. HOCl, ONOOH) with some selenium species, but these data are limited. Here we provide apparent second order rate constants for reaction of selenols (RSeH), selenides (RSeR') and diselenides (RSeSeR') with biologically-relevant oxidants (HOCl, HO, other peroxides) as well as overall consumption data for the excited state species singlet oxygen (O). Selenols show very high reactivity with HOCl and O, with rate constants > 10 M s, whilst selenides and diselenides typically react with rate constants one- (selenides) or two- (diselenides) orders of magnitude slower. Rate constants for reaction of diselenides with HO and other hydroperoxides are much slower, with k for HO being <1 M s, and for amino acid and peptide hydroperoxides ~10 M s. The rate constants determined for HOCl and O with these selenium species are greater than, or similar to, rate constants for amino acid side chains on proteins, including the corresponding sulfur-centered species (Cys and Met), suggesting that selenium containing compounds may be effective oxidant scavengers. Some of these reactions may be catalytic in nature due to ready recycling of the oxidized selenium species. These data may aid the development of highly efficacious, and catalytic, oxidant scavengers.
Topics: Hydrogen Peroxide; Hypochlorous Acid; Kinetics; Oxidants; Oxidation-Reduction; Selenium; Selenium Compounds
PubMed: 32439383
DOI: 10.1016/j.freeradbiomed.2020.05.007 -
Scientific Reports Jun 2023As a basic building block of graphene-based materials, graphene oxide (GO) plays an important role in scientific research and industrial applications. At present,...
As a basic building block of graphene-based materials, graphene oxide (GO) plays an important role in scientific research and industrial applications. At present, numerous methods have been employed to synthesize GO, there are still some issues that need to be solved, thus it is of importance to develop a green, safe and low-cost GO preparation method. Herein, a green, safe and fast method was designed to prepare GO, namely, graphite powder was firstly oxidized in a dilute sulfuric acid solution (HSO, 6 mol/L) with hydrogen peroxide (HO, 30 wt%) as oxidant, and then exfoliated to GO by ultrasonic treatment in water. In this process, HO was the only oxidant, and no other oxidants were used, thus the explosive nature of GO preparation reaction in the conventional methods could be completely eliminated. This method has other advantages such as green, fast, low-cost and no Mn-based residues. The experimental results confirm that obtained GO with oxygen-containing groups has better adsorption property compared to the graphite powder. As adsorbent, GO can remove methylene blue (50 mg/L) and Cd (56.2 mg/L) from water with removal capacity of 23.8 mg/g and 24.7 mg/g, respectively. It provides a green, fast and low-cost method to prepare GO for some applications such as adsorbent.
Topics: Graphite; Hydrogen Peroxide; Powders; Water; Oxidants; Adsorption; Water Pollutants, Chemical; Kinetics
PubMed: 37291198
DOI: 10.1038/s41598-023-36595-2 -
Biology Open Apr 2023One challenge for invading pathogens represents the exposure to highly microbicidal hypohalous acids (HOX), such as hypochlorous acid (HOCl) and hypothiocyanous acid...
One challenge for invading pathogens represents the exposure to highly microbicidal hypohalous acids (HOX), such as hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Generated at high concentrations by innate immune cells during phagocytosis, HOX kills the engulfed microbes through extensive macromolecular damage. However, microorganisms have evolved strategies to detoxify the oxidants and/or alleviate HOX-mediated damage, which improves their survival during HOX exposure. Many of these defense systems are bacteria-specific and therefore considered potential drug targets. Our minireview highlights recent (July 2021 to November 2022) advances in the field of microbial HOX defense systems and how these systems are regulated. We report recent progress on redox-sensing transcriptional regulators, two-component systems, and σ/anti-σ factors and review how oxidative modifications in these regulatory proteins affect the expression of their target genes. Moreover, we discuss novel studies that describe how HOCl affects the activity of redox-regulated enzymes and highlight mechanisms that bacteria employ to reduce HOSCN.
Topics: Oxidants; Hypochlorous Acid; Oxidation-Reduction; Bacteria
PubMed: 37102360
DOI: 10.1242/bio.059809 -
Molecules (Basel, Switzerland) Feb 2020The development of sustainable processes and products through innovative catalytic materials and procedures that allow a better use of resources is undoubtedly one of... (Review)
Review
The development of sustainable processes and products through innovative catalytic materials and procedures that allow a better use of resources is undoubtedly one of the most significant issues facing researchers nowadays. Environmental and economically advanced catalytic processes for selective oxidation of alcohols are currently focused on designing new catalysts able to activate green oxidants (dioxygen or peroxides) and applying unconventional conditions of sustainable significance, like the use of microwave irradiation as an alternative energy source. This short review aims to provide an overview of the recently (2015-2020) discovered homogeneous aerobic and peroxidative oxidations of primary and secondary alcohols catalyzed by copper complexes, highlighting new catalysts with potential application in sustainable organic synthesis, with significance in academia and industry.
Topics: Alcohols; Catalysis; Copper; Green Chemistry Technology; Humans; Microwaves; Molecular Structure; Oxidants; Oxidation-Reduction; Oxygen; Peroxides
PubMed: 32050493
DOI: 10.3390/molecules25030748