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Ecotoxicology and Environmental Safety Apr 2023Advanced oxidation processes (AOPs) are a class of highly efficient pollution remediation technologies that produce oxidising radicals under specific conditions to... (Review)
Review
Advanced oxidation processes (AOPs) are a class of highly efficient pollution remediation technologies that produce oxidising radicals under specific conditions to degrade organic pollutants. The Fenton reaction is a commonly applied AOP. To combine the advantages of AOPs and biodegradation in the remediation of organic pollutants, some studies have developed coupled systems between Fenton AOPs and white rot fungi (WRF) for environmental organic pollutant remediation and have achieved some success. Moreover, a promising system, termed as advanced bio-oxidation processes (ABOPs), mediated by the quinone redox cycling of WRF, has attracted increasing attention in the field. In this ABOP system, the radicals and HO produced through the quinone redox cycling of WRF can strengthen Fenton reaction. Meanwhile, in this process, the reduction of Fe to Fe ensures the maintenance of Fenton reaction, leading to a promising application potential for the remediation of environmental organic pollutants. ABOPs combine the advantages of bioremediation and advanced oxidation remediation. Further understanding the coupling of Fenton reaction and WRF in the degradation of organic pollutants will be of great significance for the remediation of organic pollutants. Therefore, in this study, we reviewed recent remediation techniques for organic pollutants involving the coupled application of WRF and the Fenton reaction, focusing on the application of new ABOPs mediated by WRF, and discussed the reaction mechanism and conditions of ABOPs. Finally, we discussed the application prospects and future research directions of the joint application of WRF and advanced oxidation technologies for the remediation of environmental organic pollutants.
Topics: Hydrogen Peroxide; Environmental Pollutants; Oxidation-Reduction; Environmental Restoration and Remediation; Fungi; Water Pollutants, Chemical
PubMed: 36889210
DOI: 10.1016/j.ecoenv.2023.114697 -
The Science of the Total Environment Nov 2022Ozonation has been used to effectively remove micropollutants from the secondary effluent in several wastewater treatment plants. It is known that ozonation transforms...
Ozonation has been used to effectively remove micropollutants from the secondary effluent in several wastewater treatment plants. It is known that ozonation transforms tertiary amine compounds into their respective N-oxides, however in an earlier study a mass balance could not be closed at elevated ozone concentrations, leading to the assumption that more ozonation products are possible. This study was conducted to elucidate which (hitherto unknown) ozonation products can be formed from venlafaxine and tramadol when ozonating wastewater. Ozonation experiments were performed with tramadol and venlafaxine N-oxide in two different set-ups. Both tramadol- and venlafaxine N-oxide degraded during ozonation in pure (deionized) water in both semi-continuous and batch mode ozonation set-ups. 13 and 17 new transformation products were detected from tramadol- and venlafaxine N-oxide respectively, using high resolution mass spectrometry with ESI(+) ionization. Empirical chemical formulas were proposed based on the determination of the exact masses and interpretation of the product ion spectra. These transformation products result from the addition of one to three oxygen atoms and removal of C, -CH, CH, CH, etc., from the parent molecule, respectively. Quenching experiments suggested that most of the transformation products originated from the direct reaction with ozone (eight for tramadol N-oxide and ten for venlafaxine N-oxide), whereas fewer products originated from the reaction with OH radicals (three for tramadol N-oxide and three for venlafaxine N-oxide). Reaction mechanisms and chemical structures of products are proposed, based on the available active sites and past literature on ozone reaction mechanisms. The experimental results are compared to theory and literature on ozone reactive sites and ozone reaction mechanisms. All in all this shows that there can be multiple ozonation products, and ozonation pathways can be complex, even if initially only one ozonation product is formed.
Topics: Organic Chemicals; Oxides; Ozone; Tramadol; Venlafaxine Hydrochloride; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical; Water Purification
PubMed: 35817117
DOI: 10.1016/j.scitotenv.2022.157259 -
NanoImpact Jan 2022Increased use and production of engineered nanoparticles (NPs) lead to an elevated risk of their diffuse dispersion into the aquatic environment and increased concern on...
Increased use and production of engineered nanoparticles (NPs) lead to an elevated risk of their diffuse dispersion into the aquatic environment and increased concern on unknown effects induced by their release into the aquatic ecosystem. An improved understanding of the environmental transformation processes of NPs of various surface characteristics is hence imperative for risk assessment and management. This study presents results on effects of natural organic matter (NOM) on the environmental transformation and dissolution of metal and metal oxide NPs of different surface and solubility properties in synthetic freshwater (FW) with and without NOM. Adsorption of NOM was evident on most of the studied NPs, except Sb and SbO, which resulted in the formation of negatively charged colloids of higher stability and smaller size distribution compared with the same NPs in FW only. The dissolution rate of the NPs in the presence of NOM correlated with the strength of interactions between the carboxylate group of NOM and the particle surface, and resulted in either no (Mn, Sb, ZnO NPs), increased (Co, Sn NPs) and decreased (Ni, NiO, SbO, YO NPs) levels of dissolution. One type of metal NP from each group (Mn, Ni, Sn) were investigated to assess whether observed differences in adsorption of NOM and dissolution would influence their ecotoxic potency. The results showed Mn, Ni, and Sn NPs to generate intracellular reactive oxygen species (ROS) in a time and dose-dependent manner. The extent of ROS generation in FW was similar for both Mn and Ni NPs but higher for Sn NPs. These findings are possibly related to interactions and infiltration of the NPs with the cells, which lead to redox imbalances which could induce oxidative stress and cell damage. At the same time, the presence of NOM generally reduced the intracellular ROS generation by 20-40% for the investigated NPs and also reduced cytotoxicity of Sn NPs, which can be attributed to the stronger interaction of carboxylate groups of NOM with the surface of the NPs.
Topics: Ecosystem; Metal Nanoparticles; Metals; Oxides; Reactive Oxygen Species; Zinc Oxide
PubMed: 35559892
DOI: 10.1016/j.impact.2022.100386 -
International Journal of Molecular... Oct 2023Graphitic carbon nitride (g-CN), a metal-free polymer semiconductor, has been recognized as an attractive photocatalytic material for environmental remediation because... (Review)
Review
Graphitic carbon nitride (g-CN), a metal-free polymer semiconductor, has been recognized as an attractive photocatalytic material for environmental remediation because of its low band gap, high thermal and photostability, chemical inertness, non-toxicity, low cost, biocompatibility, and optical and electrical efficiency. However, g-CN has been reported to suffer from many difficulties in photocatalytic applications, such as a low specific surface area, inadequate visible-light utilization, and a high charge recombination rate. To overcome these difficulties, the formation of g-CN heterojunctions by coupling with metal oxides has triggered tremendous interest in recent years. In this regard, zinc oxide (ZnO) is being largely explored as a self-driven semiconductor photocatalyst to form heterojunctions with g-CN, as ZnO possesses unique and fascinating properties, including high quantum efficiency, high electron mobility, cost-effectiveness, environmental friendliness, and a simple synthetic procedure. The synergistic effect of its properties, such as adsorption and photogenerated charge separation, was found to enhance the photocatalytic activity of heterojunctions. Hence, this review aims to compile the strategies for fabricating g-CN/ZnO-based Z-scheme and S-scheme heterojunction photocatalytic systems with enhanced performance and overall stability for the photodegradation of organic pollutants. Furthermore, with reference to the reported system, the photocatalytic mechanism of g-CN/ZnO-based heterojunction photocatalysts and their charge-transfer pathways on the interface surface are highlighted.
Topics: Zinc Oxide; Photolysis; Oxides; Environmental Pollutants
PubMed: 37834469
DOI: 10.3390/ijms241915021 -
International Journal of Molecular... Jan 2023Classically, superoxide anion O and reactive oxygen species ROS play a dual role. At the physiological balance level, they are a by-product of O reduction, necessary for... (Review)
Review
Classically, superoxide anion O and reactive oxygen species ROS play a dual role. At the physiological balance level, they are a by-product of O reduction, necessary for cell signalling, and at the pathological level they are considered harmful, as they can induce disease and apoptosis, necrosis, ferroptosis, pyroptosis and autophagic cell death. This revision focuses on understanding the main characteristics of the superoxide O, its generation pathways, the biomolecules it oxidizes and how it may contribute to their modification and toxicity. The role of superoxide dismutase, the enzyme responsible for the removal of most of the superoxide produced in living organisms, is studied. At the same time, the toxicity induced by superoxide and derived radicals is beneficial in the oxidative death of microbial pathogens, which are subsequently engulfed by specialized immune cells, such as neutrophils or macrophages, during the activation of innate immunity. Ultimately, this review describes in some depth the chemistry related to O and how it is harnessed by the innate immune system to produce lysis of microbial agents.
Topics: Superoxides; Reactive Oxygen Species; Superoxide Dismutase; Apoptosis; Immunity, Innate
PubMed: 36768162
DOI: 10.3390/ijms24031841 -
Journal of the American Chemical Society Dec 2019The enantioselective, vicinal diamination of alkenes represents one of the stereocontrolled additions that remains an outstanding challenge in organic synthesis. A...
The enantioselective, vicinal diamination of alkenes represents one of the stereocontrolled additions that remains an outstanding challenge in organic synthesis. A general solution to this problem would enable the efficient and selective preparation of widely useful, enantioenriched diamines for applications in medicinal chemistry and catalysis. In this article, we describe the first enantioselective, diamination of simple alkenes mediated by a chiral, enantioenriched organoselenium catalyst together with a bistosyl urea as the bifunctional nucleophile and fluorocollidinium tetrafluoroborate as the stoichiometric oxidant. Diaryl, aryl-alkyl, and alkyl-alkyl olefins bearing a variety of substituents are all diaminated in consistently high enantioselectivities but variable yields. The reaction likely proceeds through a Se(II)/Se(IV) redox catalytic cycle reminiscent of the dichlorination reported previously. Furthermore, the -stereospecificity of the transformation shows promise for highly enantioselective diaminations of alkenes with no strong steric or electronic bias.
Topics: Alkenes; Amination; Catalysis; Diamines; Organoselenium Compounds; Oxidants; Oxidation-Reduction; Stereoisomerism; Urea
PubMed: 31742399
DOI: 10.1021/jacs.9b11261 -
International Journal of Molecular... Oct 2022Although graphitic carbon nitride (g-CN) has been reported for several decades, it is still an active material at the present time owing to its amazing properties... (Review)
Review
Although graphitic carbon nitride (g-CN) has been reported for several decades, it is still an active material at the present time owing to its amazing properties exhibited in many applications, including photocatalysis. With the rapid development of characterization techniques, in-depth exploration has been conducted to reveal and utilize the natural properties of g-CN through modifications. Among these, the assembly of g-CN with metal oxides is an effective strategy which can not only improve electron-hole separation efficiency by forming a polymer-inorganic heterojunction, but also compensate for the redox capabilities of g-CN owing to the varied oxidation states of metal ions, enhancing its photocatalytic performance. Herein, we summarized the research progress on the synthesis of g-CN and its coupling with single- or multiple-metal oxides, and its photocatalytic applications in energy production and environmental protection, including the splitting of water to hydrogen, the reduction of CO to valuable fuels, the degradation of organic pollutants and the disinfection of bacteria. At the end, challenges and prospects in the synthesis and photocatalytic application of g-CN-based composites are proposed and an outlook is given.
Topics: Catalysis; Nitrogen Compounds; Graphite; Oxides
PubMed: 36361768
DOI: 10.3390/ijms232112979 -
Molecules (Basel, Switzerland) Jun 2022The chemistry of polyvalent iodine compounds has piqued the interest of researchers due to their role as important and flexible reagents in synthetic organic chemistry,... (Review)
Review
The chemistry of polyvalent iodine compounds has piqued the interest of researchers due to their role as important and flexible reagents in synthetic organic chemistry, resulting in a broad variety of useful organic molecules. These chemicals have potential uses in various functionalization procedures due to their non-toxic and environmentally friendly properties. As they are also strong electrophiles and potent oxidizing agents, the use of hypervalent iodine reagents in palladium-catalyzed transformations has received a lot of attention in recent years. Extensive research has been conducted on the subject of C-H bond functionalization by Pd catalysis with hypervalent iodine reagents as oxidants. Furthermore, the iodine(III) reagent is now often used as an arylating agent in Pd-catalyzed C-H arylation or Heck-type cross-coupling processes. In this article, the recent advances in palladium-catalyzed oxidative cross-coupling reactions employing hypervalent iodine reagents are reviewed in detail.
Topics: Catalysis; Indicators and Reagents; Iodides; Iodine; Oxidants; Oxidation-Reduction; Palladium
PubMed: 35745020
DOI: 10.3390/molecules27123900 -
Journal of Hazardous Materials Feb 2023Microplastics (MPs) are contaminants of emerging concern that accumulate in various environments, where they pose threats to both the ecosystem and public health. Since... (Review)
Review
Microplastics (MPs) are contaminants of emerging concern that accumulate in various environments, where they pose threats to both the ecosystem and public health. Since MPs have been detected in drinking water resources and wastewater effluents, more efficient treatment is needed at wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs). This review discusses the potential of biological, photochemical, Fenton (-like) systems, ozonation, and other oxidation processes in the treatment of MPs in terms of their indicators of oxidation such as mass loss and surface oxidation. The oxidation processes were further analyzed in terms of limitations and environmental implications. Most previous studies examining MPs degradation using conventional treatments-such as UV disinfection, ozonation, and chlorination-employed significantly higher doses than the common doses applied in DWTPs and WWTPs. Owing to such dose gaps, the oxidative transformation of MPs observed in many previous studies are not likely to occur under practical conditions. Some novel oxidation processes showed promising MPs treatment efficiencies, while many of them have not yet been applied on a larger scale due to high costs and the lack of extensive basic research. Health and environmental impacts related to the discharge of oxidized MPs in effluents should be considered carefully in different aspects: the role as vectors of external pollutants, release of organic compounds (including organic byproducts from oxidation) and fragmentation into smaller particles as MPs circulate in the ecosystem as well as the possibility of bioaccumulation. Future research should also focus on ways to incorporate developed oxidation processes in DWTPs and WWTPs to mitigate MPs contamination.
Topics: Microplastics; Plastics; Ecosystem; Drinking Water; Water Pollutants, Chemical; Water Purification; Wastewater; Ozone; Oxidative Stress
PubMed: 36372022
DOI: 10.1016/j.jhazmat.2022.130313 -
Toxicology and Applied Pharmacology Jul 2022Workers in the oil and gas extraction industry are at risk of inhaling volatile organic compounds. Epidemiological studies suggest oil vapor inhalation may affect...
Workers in the oil and gas extraction industry are at risk of inhaling volatile organic compounds. Epidemiological studies suggest oil vapor inhalation may affect cardiovascular health. Thus, in this hazard identification study we investigated the effects of inhalation of crude oil vapor (COV) on cardiovascular function. Male rats were exposed to air or COV (300 ppm) for 6 h (acute), or 6 h/day × 4 d/wk. × 4 wk. (sub-chronic). The effects of COV inhalation were assessed 1, 28, and 90 d post-exposure. Acute exposure to COV resulted in reductions in mean arterial and diastolic blood pressures 1 and 28 d after exposure, changes in nitrate-nitrite and HO levels, and in the expression of transcripts and proteins that regulate inflammation, vascular remodeling, and the synthesis of nitric oxide (NO) in the heart and kidneys. The sub-chronic exposure resulted in a reduced sensitivity to α-adrenoreceptor-mediated vasoconstriction in vitro 28 d post-exposure, and a reduction in oxidative stress in the heart. Sub-chronic COV exposure led to alterations in the expression of NO synthases and anti-oxidant enzymes, which regulate inflammation and oxidative stress in the heart and kidneys. There seems to be a balance between changes in the expression of transcripts associated with the generation of reactive oxygen species (ROS) and antioxidant enzymes. The ability of antioxidant enzymes to reduce or inhibit the effects of ROS may allow the cardiovascular system to adapt to acute COV exposures. However, sub-chronic exposures may result in longer-lasting negative health consequences on the cardiovascular system.
Topics: Animals; Antioxidants; Cardiovascular System; Gases; Hydrogen Peroxide; Inflammation; Inhalation Exposure; Male; Oxidative Stress; Petroleum; Rats; Reactive Oxygen Species
PubMed: 35598716
DOI: 10.1016/j.taap.2022.116071