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Chemical Society Reviews Jul 2022Carbon-hydrogen bond functionalizations provide an attractive method for streamlining organic synthesis, and many strategies have been developed for conducting these... (Review)
Review
Carbon-hydrogen bond functionalizations provide an attractive method for streamlining organic synthesis, and many strategies have been developed for conducting these transformations. Hydride-abstracting reactions have emerged as extremely effective methods for oxidative bond-forming processes due to their mild reaction conditions and high chemoselectivity. This review will predominantly focus on the mechanism, reaction development, natural product synthesis applications, approaches to catalysis, and use in enantioselective processes for hydride abstractions by quinone, oxoammonium ion, and carbocation oxidants. These are the most commonly employed hydride-abstracting agents, but recent efforts illustrate the potential for weaker ketone and triaryl borane oxidants, which will be covered at the end of the review.
Topics: Carbon; Catalysis; Chemistry Techniques, Synthetic; Oxidants; Oxidation-Reduction
PubMed: 35712818
DOI: 10.1039/d1cs01169c -
The Science of the Total Environment Mar 2023The ammonia oxidation process driven by microorganisms is an essential source of nitrous oxide (NO) and nitric oxide (NO) emissions. However, few evaluations have been...
The ammonia oxidation process driven by microorganisms is an essential source of nitrous oxide (NO) and nitric oxide (NO) emissions. However, few evaluations have been performed on the changes in the community structure and abundance of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) under substituting portion of chemical fertilizers with organic manure (organic substitution) and their relative contribution to the ammonia oxidation process. Here, five long-term fertilization strategies were applied in field (SN: synthetic fertilizer application; OM: organic manure; M1N1: substituting 50 % of chemical N fertilizer with organic manure; M1N4: substituting 20 % of chemical N fertilizer with organic manure; and CK: no fertilizer). We investigated the response characteristics of AOB and AOA community structures by selective inhibitor shaking assays and high-throughput sequencing and further explained their relative contribution to the ammonia oxidation process during three consecutive years of vegetable production. Compared to SN and M1N4, the potential of ammonia oxidation (PAO) was significantly reduced by 26.4 % and 22.3 % in OM and 9.5 % and 4.4 % in M1N1, resulting in NO reductions of 38.9 % and 30.8 % (OM) and 31.2 % and 21.1 % (M1N1), respectively, and NO reductions of 45.0 % and 34.1 % (OM) and 40.1 % and 28.3 % (M1N1). RDA and correlation analyses showed that the soil organic carbon and ammonium nitrogen content increased while AOB gene abundance and diversity significantly decreased with increasing organic replacement ratio; however, the relative abundance of Nitrosomonas in AOB increased in OM and M1N1, which further demonstrates that AOB are the main driver in vegetable soils. Therefore, the appropriate proportion of organic substitution (OM and M1N1) could decrease the NO and NO emissions contributed by AOB by affecting the soil physicochemical properties and AOB community structure.
Topics: Soil; Nitric Oxide; Vegetables; Nitrosomonas; Ammonia; Carbon; Manure; Oxidation-Reduction; Archaea; Betaproteobacteria; Fertilizers; Soil Microbiology; Nitrification
PubMed: 36586678
DOI: 10.1016/j.scitotenv.2022.161231 -
Environmental Pollution (Barking, Essex... Jan 2022Fe-based catalysts as low-cost, high-efficiency, and non-toxic materials display superior catalytic performances in activating hydrogen peroxide, persulfate (PS),... (Review)
Review
Fe-based catalysts as low-cost, high-efficiency, and non-toxic materials display superior catalytic performances in activating hydrogen peroxide, persulfate (PS), peracetic acid (PAA), percarbonate (PC), and ozone to degrade organic contaminants in aqueous solutions. They mainly include ferrous salts, zero-valent iron, iron-metal composites, iron sulfides, iron oxyhydroxides, iron oxides, and supported iron-based catalysts, which have been widely applied in advanced oxidation processes (AOPs). However, there is lack of a comprehensive review systematically reporting their synthesis, characterization, and applications. It is imperative to evaluate the catalytic performances of various Fe-based catalysts in diverse AOPs systems and reveal the activation mechanisms of different oxidants by Fe-based catalysts. This work detailedly summarizes the synthesis methods and characterization technologies of Fe-based catalysts. This paper critically evaluates the catalytic performances of Fe-based catalysts in diverse AOPs systems. The effects of solution pH, reaction temperature, coexisting ions, oxidant concentration, catalyst dosage, and external energy on the degradation of organic contaminants in the Fe-based catalyst/oxidant systems and the stability of Fe-based catalysts are also discussed. The activation mechanisms of various oxidants and the degradation pathways of organic contaminants in the Fe-based catalyst/oxidant systems are revealed by a series of novel detection methods and characterization technologies. Future research prospects on the potential preparation means of Fe-based catalysts, practical applications, assistive technologies, and impact in AOPs are proposed.
Topics: Catalysis; Hydrogen Peroxide; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification
PubMed: 34822943
DOI: 10.1016/j.envpol.2021.118565 -
The Science of the Total Environment Feb 2021Lead is a toxic environmental contaminant associated with current and historic mine sites. Here we studied the natural attenuation of Pb in a limestone cave system that...
Lead is a toxic environmental contaminant associated with current and historic mine sites. Here we studied the natural attenuation of Pb in a limestone cave system that receives drainage from the ancient Priddy Mineries, UK. Extensive deposits of manganese oxides were observed to be forming on the cave walls and as coatings in the stream beds. Analysis of these deposits identified them as birnessite (δ-MnO), with some extremely high concentrations of sorbed Pb (up to 56 wt%) also present. We hypothesised that these cave crusts were actively being formed by microbial Mn(II)-oxidation, and to investigate this the microbial communities were characterised by DNA sequencing, enrichment and isolation experiments. The birnessite deposits contained abundant and diverse prokaryotes and fungi, with ~5% of prokaryotes and ~ 10% of fungi closely related to known heterotrophic Mn(II)-oxidisers. A substantial proportion (up to 17%) of prokaryote sequences were assigned to groups known as autotrophic ammonia and nitrite oxidisers, suggesting that nitrogen cycling may play an important role in contributing energy and carbon to the cave crust microbial communities and consequently the formation of Mn(IV) oxides and Pb attenuation. Enrichment and isolation experiments showed that the birnessite deposits contained Mn(II)-oxidising microorganisms, and two isolates (Streptomyces sp. and Phyllobacterium sp.) could oxidise Mn(II) in the presence of 0.1 mM Pb. Supplying the enrichment cultures with acetate as a source of energy and carbon stimulated Mn(II)-oxidation, but excess organics in the form of glucose generated aqueous Mn(II), likely via microbial Mn(IV)-reduction. In this karst cave, microbial Mn(II)-oxidation contributes to the active sequestration and natural attenuation of Pb from contaminated waters, and therefore may be considered a natural analogue for the design of wastewater remediation systems and for understanding the geochemical controls on karst groundwater quality, a resource relied upon by billions of people across the globe.
Topics: Groundwater; Humans; Lead; Manganese; Manganese Compounds; Oxidation-Reduction; Oxides
PubMed: 33254903
DOI: 10.1016/j.scitotenv.2020.142312 -
Inorganic Chemistry May 2024One of the crucial metabolic processes for both plant and animal kingdoms is the oxidation of the amino acid tryptophan (TRP) that regulates plant growth and controls...
One of the crucial metabolic processes for both plant and animal kingdoms is the oxidation of the amino acid tryptophan (TRP) that regulates plant growth and controls hunger and sleeping patterns in animals. Here, we report revolutionary insights into how this process can be crucially affected by interactions with metal oxide nanoparticles (NPs), creating a toolbox for a plethora of important biomedical and agricultural applications. Molecular mechanisms in TRP-NP interactions were revealed by NMR and optical spectroscopy for ceria and titania and by X-ray single-crystal study and a computational study of model TRP-polyoxometalate complexes, which permitted the visualization of the oxidation mechanism at an atomic level. Nanozyme activity, involving concerted proton and electron transfer to the NP surface for oxides with a high oxidative potential, like CeO or WO, converted TRP in the first step into a tricyclic organic acid belonging to the family of natural plant hormones, auxins. TiO, a much poorer oxidant, was strongly binding TRP without concurrent oxidation in the dark but oxidized it nonspecifically via the release of reactive oxygen species (ROS) in daylight.
Topics: Cerium; Metal Nanoparticles; Models, Molecular; Oxidation-Reduction; Oxides; Titanium; Tryptophan
PubMed: 38684718
DOI: 10.1021/acs.inorgchem.3c03674 -
Molecules (Basel, Switzerland) Dec 2022The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their...
The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their natural oxidative degradation in clay soils and to evaluate the ecotoxicity of mixtures partially oxidized on the species , a biodiversity representative of plants in the aquatic environment. Kinetic data showed that the adsorption of organic pollutants on clay particles obeys the pseudo-second-order model, while the adsorption isotherms satisfactorily fit the Langmuir model. Adsorption reduces the dispersion of the organic pollutant in the environment and prolongs its persistence and its natural degradation probability. Measurements of the Zeta potential and particle size as a function of pH demonstrate that the catalytic activity of clay depends on its cation, its silica/alumina ratio, and therefore on its permanent and temporary ion exchange capacities. These factors seem to govern its delamination and dispersion in aqueous media, its hydrophilic-hydrophobic character, and its porosity. Tests conducted on in contact with ozonation mixtures revealed that the toxicity could be due to pH decrease and to the toxicity of the intermediates yielded. Ecotoxicity would depend on the structure of the organic molecules, the chemical composition of the clay surface and ozonation time, which determines the oxidation progress. These results are of great importance for further research because they allow concluding that the negative impact of the persistence of an organic molecule in clay-containing media depends on the type and composition of the very clay mineral.
Topics: Clay; Aluminum Silicates; Environmental Pollutants; Water; Molecular Structure; Catalysis; Ozone; Adsorption; Water Pollutants, Chemical; Bentonite
PubMed: 36615416
DOI: 10.3390/molecules28010222 -
Journal of Hazardous Materials Oct 2022Fe-Mn oxide-based composites have been widely used in the solidification of heavy metals or the removal of organic pollutants, which can not only show excellent... (Review)
Review
Fe-Mn oxide-based composites have been widely used in the solidification of heavy metals or the removal of organic pollutants, which can not only show excellent adsorption/oxidation performance, but also show catalytic activity for common oxidants. At present, the correlation between adsorption/oxidation/catalytic performance and physicochemical characteristics of these composites, and the underlying mechanisms are still unclear. Therefore, the main purpose of this review is to disclose the internal relationship between the physicochemical properties of Fe-Mn oxide-based composites and the pollutant removal performance. From the perspective of crystal phase, the basic units of Fe-Mn oxide composites are divided into Fe-Mn binary oxide (FMBO) and spinel MnFeO, and the two species were discussed separately in most chapters. The selected physicochemical properties mainly include the type of Fe-Mn oxide composites, surface-to-volume ratio, pore volume, pH, crystal type, surface functional groups. Because the physicochemical properties that determine how effective Fe-Mn oxide material is at removing contaminants may differ as it performs different functions, we discussed the above problems under different application scenarios (adsorption, oxidation, and advanced oxidation process). Additionally, internal factor (Fe/Mn mole ratio) and external factors (pH, co-ions and ionic strength) were analyzed, and several common synthetic strategies of these composites were presented.
Topics: Adsorption; Catalysis; Oxidation-Reduction; Oxides; Water Pollutants, Chemical
PubMed: 35872460
DOI: 10.1016/j.jhazmat.2022.129631 -
Water Research Aug 2023Sole O or HO oxidant hardly oxidize Sb(III) on a time scale of hours to days, but Sb(III) oxidation can simultaneously occur in Fe(II) oxidation by O and HO due to the...
Sole O or HO oxidant hardly oxidize Sb(III) on a time scale of hours to days, but Sb(III) oxidation can simultaneously occur in Fe(II) oxidation by O and HO due to the generation of reactive oxygen species (ROS). However, Sb(III) and Fe(II) co-oxidation mechanisms regarding the dominant ROS and effects of organic ligands require further elucidation. Herein, the co-oxidation of Sb(III) and Fe(II) by O and HO was studied in detail. The results indicated that increasing the pH significantly increased Sb(III) and Fe(II) oxidation rates during Fe(II) oxygenation, while the highest Sb(III) oxidation rate and oxidation efficiency was obtained at pH 3 with HO as the oxidant. HCO and HPOanions exerted different effects on Sb(III) oxidation in Fe(II) oxidation processes by O and HO. In addition, Fe(II) complexed with organic ligands could improve Sb(III) oxidation rates by 1 to 4 orders of magnitude mainly due to more ROS production. Moreover, quenching experiments combined with the PMSO probe demonstrated that OH was the main ROS at acidic pH, whereas Fe(IV) played a key role in Sb(III) oxidation at near-neutral pH. In particular, the steady-state concentration of Fe(IV) ([Fe(IV)]) and k were determined to be 1.66×10 M and 2.57×10 M s, respectively. Overall, these findings help to better understand the geochemical cycling and fate of Sb in Fe(II)- and DOM-rich subsurface environments undergoing redox fluctuations and are conductive to developing Fenton reactions for the in-situ remediation of Sb(III)-contaminated environments.
Topics: Hydrogen Peroxide; Reactive Oxygen Species; Oxygen; Ligands; Oxidation-Reduction; Oxidants; Ferrous Compounds; Ferric Compounds
PubMed: 37413752
DOI: 10.1016/j.watres.2023.120296 -
Environmental Toxicology and Chemistry Apr 2020Chlorination is commonly used to control biofouling organisms, but chlorine rapidly hydrolyzes in seawater to hypochlorite, which undergoes further reaction with... (Review)
Review
Chlorination is commonly used to control biofouling organisms, but chlorine rapidly hydrolyzes in seawater to hypochlorite, which undergoes further reaction with bromide, and then with organic matter. These reaction products, collectively termed chlorine-produced oxidants (CPOs), can be toxic to marine biota. Because the lifetime of the most toxic forms is limited to several days, appropriate guideline values need to be based on short-term (acute) toxicity tests, rather than chronic tests. Flow-through toxicity tests that provide continuous CPO exposure are the most appropriate, whereas static-renewal tests generate variable exposure and effects depending on the renewal rate. There are literature data for acute CPO toxicity from flow-through tests, together with values from 2 sensitive 15-min static tests on 30 species from 9 taxonomic groups. These values were used in a species sensitivity distribution (SSD) to derive guideline values that were protective of 99, 95, and 90% of species at 2.2, 7.2, and 13 µg CPO/L respectively. These are the first marine guideline values for chlorine to be derived using SSDs, with all other international guideline values based on the use of assessment factors applied to data for the most sensitive species. In applying these conservative guideline values in field situations, it would need to be demonstrated that concentrations of CPOs would be reduced to below the guideline value within an acceptable mixing zone through both dilution and dissociation. Environ Toxicol Chem 2020;39:754-764. © 2020 SETAC.
Topics: Animals; Aquatic Organisms; Biota; Chlorine; Guidelines as Topic; Hypochlorous Acid; Lethal Dose 50; Oxidants; Risk Assessment; Seawater; Species Specificity; Toxicity Tests; Water Pollutants, Chemical
PubMed: 31907965
DOI: 10.1002/etc.4661 -
Water Research Jan 2023Application of heterogeneous advanced oxidation processes (AOPs) for wastewater treatment suffers from the low oxidant utilization efficiency, slow catalytic cycling and...
Application of heterogeneous advanced oxidation processes (AOPs) for wastewater treatment suffers from the low oxidant utilization efficiency, slow catalytic cycling and severe matrix interference. Herein, we report that amorphous zirconium dioxide (aZrO), a redox-inert metal oxide, can efficiently activate peroxymonosulfate (PMS) to degrade organic micropollutants under very low oxidant doses and complex coexisting matrices. Distinct from conventional AOPs where radicals are formed, the surface Zr(IV)-PMS* complex was identified as the principal reactive species, and primarily conducted oxygen-atom-transfer route with selected molecules. Quantitative structure-activity relationship analysis indicated that the formation of Zr(IV)-PMS* complex was governed by the density of the surface hydroxyl groups. The strong interaction between the Zr atom and PMS caused the deviation of the negative charge from Zr(IV) metal sites to the oxidant. As a result, the O-O bond of the adsorbed PMS was prolonged and its oxidation potential elevated, which enabled it to directly react with contaminants. This study indicates the potential of aZrO as a novel and eco-friendly catalyst that activates PMS to selectively tackle organic contaminants, and sheds light on the designing of Fenton-like catalysts using redox-inert metals.
Topics: Peroxides; Organic Chemicals; Oxidants; Quantitative Structure-Activity Relationship
PubMed: 36434974
DOI: 10.1016/j.watres.2022.119363