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Chemosphere Sep 2023Manganese oxides (MnOx) are recognized as a strongest oxidant and adsorbent, of which composites have been proved to be effective in the removal of contaminants from... (Review)
Review
Manganese oxides (MnOx) are recognized as a strongest oxidant and adsorbent, of which composites have been proved to be effective in the removal of contaminants from wastewater. This review provides a comprehensive analysis of Mn biochemistry in water environment including Mn oxidation and Mn reduction. The recent research on the application of MnOx in the wastewater treatment was summarized, including the involvement of organic micropollutant degradation, the transformation of nitrogen and phosphorus, the fate of sulfur and the methane mitigation. In addition to the adsorption capacity, the Mn cycling mediated by Mn(II) oxidizing bacteria and Mn(IV) reducing bacteria is the driving force for the MnOx utilization. The common category, characteristics and functions of Mn microorganisms in recent studies were also reviewed. Finally, the discussion on the influence factors, microbial response, reaction mechanism and potential risk of MnOx application in pollutants' transformation were proposed, which might be the promising opportunities for the future investigation of MnOx application in wastewater treatment.
Topics: Manganese; Wastewater; Oxides; Manganese Compounds; Oxidation-Reduction; Bacteria
PubMed: 37327824
DOI: 10.1016/j.chemosphere.2023.139219 -
Current Protein & Peptide Science 2022Laccases and peroxidases have attracted great interest for industrial and environmental applications. These enzymes have a broad substrate range and a robust oxidizing...
AIM
Laccases and peroxidases have attracted great interest for industrial and environmental applications. These enzymes have a broad substrate range and a robust oxidizing ability. Moreover, using mediators or co-oxidants makes it possible to increase their catalytic activity and extend their substrate scope to more resistant chemical structures.
BACKGROUND
Fungal laccases and ligninolytic peroxidases, mainly lignin and manganese peroxidases, are the privileged oxidoreductases for bioremediation processes. Nonetheless, an increasing diversity of laccases and peroxidase-type enzymes has been proposed for environmental technologies.
OBJECTIVE
This article aims to provide an overview of these enzymes and compare their applicability in the degradation of organic pollutants.
METHODS
Fundamental properties of the proteins are covered and applications towards polycyclic aromatic hydrocarbons (PAHs) and pesticides are specially focused.
RESULTS
Laccases are multicopper oxidases initially studied for applications in the pulp and paper industry but able to oxidize a variety of environmentally concerning compounds. Relying on O, laccases do not require peroxides nor auxiliary agents, like Mn, although suitable redox mediators are needed to attack the more recalcitrant pollutants (e.g., PAHs). True and pseudo-peroxidases use a stronger oxidant (HO) and the redox chemistry at the heme site generates high potential species that allow the oxidation of dyes and some pesticides.
CONCLUSION
Lately, research efforts have been directed to enzyme discovery, testing with micropollutants, and improving biocatalysts' stability by immobilization and protein engineering. Further understanding of the effects of natural media components and solvents on the enzymes might lead to competitive enzymatic treatments of highly toxic media.
Topics: Laccase; Biodegradation, Environmental; Lignin; Environmental Pollutants; Peroxidase; Hemeproteins; Hydrogen Peroxide; Manganese; Peroxidases; Oxidation-Reduction; Polycyclic Aromatic Hydrocarbons; Heme; Pesticides; Coloring Agents; Oxidants; Solvents
PubMed: 35794739
DOI: 10.2174/1389203723666220704090416 -
Water Research Apr 2023The fact that 94% of microplastics (MPs) ubiquitous in the environment are subject to natural weathering makes the aging study currently a research hotspot. This review... (Review)
Review
The fact that 94% of microplastics (MPs) ubiquitous in the environment are subject to natural weathering makes the aging study currently a research hotspot. This review summarized the physicochemical characteristics of MPs undergoing natural and artificial aging and evaluated current analytical methods used in aging studies. Besides, the differences in photoaging and aging induced by advanced oxidation processes (AOPs) were discussed, leading to a conclusion that AOPs composed of oxidant and ultraviolet (UV) irradiation can better facilitate the alteration of MPs compared to UV irradiation alone. In addition, the environmental behavior of aged MPs was outlined and their adsorption properties for organics and metals were highlighted as a result of combined effects of hydrophobic, π-π, diffusion, and hydrogen bond interaction. Furthermore, the mechanisms of photoaging and AOPs-initiated aging were analyzed, mainly the role of reactive oxygen species (ROS) and environmentally persistent free radicals (EPFRs). Finally, the applications of two-dimensional correlation spectroscopy (2D-COS) and three-dimensional fluorescence spectra using excitation emission matrix-parallel factor analysis (EEM-PARAFAC) were discussed for the aging process analysis. This overview plays an important role in explaining the aging characteristics of MPs and provides a theoretical foundation for further investigations into their toxicity and removal.
Topics: Microplastics; Plastics; Skin Aging; Water Pollutants, Chemical; Oxidants
PubMed: 36774752
DOI: 10.1016/j.watres.2023.119628 -
Water Research Sep 2021Liquid sludge often contains odorous and toxic hydrogen sulfide and high levels of Fe compounds (e.g., iron sulfides), due to the extensive use of iron salts for...
Simultaneous removal of hydrogen sulfide, phosphate and emerging organic contaminants, and improvement of sludge dewaterability by oxidant dosing in sulfide-iron-laden sludge.
Liquid sludge often contains odorous and toxic hydrogen sulfide and high levels of Fe compounds (e.g., iron sulfides), due to the extensive use of iron salts for hydrogen sulfide control in sewers and for enhanced primary treatment and phosphate removal in wastewater treatment plants. We proposed and verified that dosing appropriate chemical oxidants in the sulfide-iron-laden sludge can be a simple and cost-effective strategy to remove hydrogen sulfide, phosphate, and emerging organic contaminants, and to improve sludge dewaterability simultaneously. Among the seven oxidants investigated, HO, ClO and NaClO were the more cost-effective oxidants than others to control hydrogen sulfide release from the liquid sludge. Dosing these three oxidants also improved sludge dewaterability and removed dissolved phosphate from the liquid sludge, with HO performing the best. Hydrogen sulfide was removed via both direct oxidation by the dosed oxidants and indirect oxidation by the Fe that was in-situ formed from oxidation of the Fe compounds in the sludge. The in-situ formed Fe also precipitated/adsorbed the soluble phosphate into the solid form (FePO). Fenton-like reactions occurred between HO and the Fe compounds in the sludge, and hydroxyl radicals (HO•) were generated. HO• oxidized hydrogen sulfide, destructed refractory organic emerging contaminants and sludge extracellular polymeric compounds (EPSs), and improved the sludge dewaterability. The formation of HO• can be enhanced by hydrogen sulfide and the sludge EPSs present in the sludge through providing more available Fe for the Fenton-like reactions. This study demonstrates the importance of selecting and dosing suitable oxidants to the sulfide-iron-laden sludge with due consideration for the multiple benefits in engineering practices. The same principles may be also used in formulating a dual oxidant-iron strategy to treat sulfide-iron-laden sewage, sludge, and sediments for simultaneous abatement of various pollutants.
Topics: Hydrogen Peroxide; Hydrogen Sulfide; Iron; Oxidants; Oxidation-Reduction; Phosphates; Sewage; Sulfides; Waste Disposal, Fluid
PubMed: 34418644
DOI: 10.1016/j.watres.2021.117557 -
Journal of Bacteriology Nov 2020Here, we investigate the mycobacterial response to the combined stress of an organic oxidant (cumene hydroperoxide [CHP]) and a solvent (ethanol). To understand the...
Here, we investigate the mycobacterial response to the combined stress of an organic oxidant (cumene hydroperoxide [CHP]) and a solvent (ethanol). To understand the interaction between the two stressors, we treated cells to a range of ethanol concentrations (2.5% to 10% [vol/vol]) in combination with a subinhibitory concentration of 1 mM CHP. It was observed that the presence of CHP increases the efficacy of ethanol in inducing rapid cell death. The data further suggest that ethanol reacts with the alkoxy radicals to produce ethanol-derived peroxides. These radicals induce significant membrane damage and lead to cell lysis. The ethanol-derived radicals were primarily recognized by the cells as organic radicals, as was evident by the differential upregulation of the genes that function in cells treated with the combination of ethanol and CHP. The role of organic peroxide reductase, Ohr, was further confirmed by the significantly higher sensitivity of the deletion mutant to CHP and the combined stress treatment of CHP and ethanol. Moreover, we also observed the sigma factor σ to be important for the cells treated with ethanol alone as well as the aforementioned combination. A Δ mutant strain had significantly higher susceptibility to the stress conditions. This finding was correlated with the σ-dependent transcriptional regulation of and In summary, our data indicate that the combination of low levels of ethanol and organic peroxides induce ethanol-derived organic radicals that lead to significant oxidative stress on the cells in a concentration-dependent manner. Bacterial response to a combination of stresses can be unexpected and very different compared with that of an individual stress treatment. This study explores the physiological and transcriptional response of mycobacteria in response to the combinatorial treatment of an oxidant with the commonly used solvent ethanol. The presence of a subinhibitory concentration of organic peroxide increases the effectiveness of ethanol by inducing reactive peroxides that destroy the membrane integrity of cells in a significantly short time span. Our work elucidates a mechanism of targeting the complex mycobacterial membrane, which is its primary source of intrinsic resistance. Furthermore, it also demonstrates the importance of exploring the effect of various stress conditions on inducing bacterial clearance.
Topics: Bacterial Proteins; Benzene Derivatives; Ethanol; Gene Expression Regulation, Bacterial; Mycobacterium smegmatis; Oxidants; Oxidative Stress
PubMed: 32928928
DOI: 10.1128/JB.00222-20 -
Environmental Science & Technology Oct 2022Iron (Fe) minerals constitute a major control on organic carbon (OC) storage in soils and sediments. While previous research has mainly targeted Fe (oxyhydr)oxides, the...
Iron (Fe) minerals constitute a major control on organic carbon (OC) storage in soils and sediments. While previous research has mainly targeted Fe (oxyhydr)oxides, the impact of Fe sulfides and their subsequent oxidation on OC dynamics remains unresolved in redox-fluctuating environments. Here, we investigated the impact of dissolved organic matter (DOM) on FeS oxidation and how FeS and its oxidation may alter the retention and nature of DOM. After the anoxic reaction of DOM with FeS, FeS preferentially removed high-molecular-weight and nitrogen-rich compounds and promoted the formation of aqueous sulfurized organic molecules, according to Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) analysis. When exposed to O, FeS oxidized to nanocrystalline lepidocrocite and additional aqueous sulfurized organic compounds were generated. The presence of DOM decreased the particle size of the resulting nano-lepidocrocite based on Mössbauer spectroscopy. Following FeS oxidation, most solid-phase OC remained associated with the newly formed lepidocrocite via a monodentate chelating mechanism (based on FTIR analysis), and FeS oxidation caused only a slight increase in the solubilization of solid-phase OC. Collectively, this work highlights the under-appreciated role of Fe sulfides and their oxidation in driving OC transformation and preservation.
Topics: Carbon; Dissolved Organic Matter; Ferric Compounds; Iron; Minerals; Nitrogen; Nitrogen Compounds; Oxidation-Reduction; Oxides; Soil; Sulfides; Water
PubMed: 36151962
DOI: 10.1021/acs.est.1c08727 -
Water Research Feb 2021Synthetic or natural mediators (Med) can enhance the transformation of different types of organic pollutants by mild oxidants, which has been extensively studied in... (Review)
Review
Synthetic or natural mediators (Med) can enhance the transformation of different types of organic pollutants by mild oxidants, which has been extensively studied in literature. This enhancing effect is attributed to the following two steps: (i) mild oxidants react with Med forming Med with higher reactivity, and then (ii) these organic pollutants are more readily transformed by Med. The present work reviews the latest findings on the formation of Med from the reactions of synthetic (i.e., 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) and 1-hydroxybenzotriazole (HBT)) or natural mediators (i.e., syringaldehyde (SA), acetosyringone (AS), p-coumaric acid, and catechol) with mild oxidants such as laccase, manganese oxidants including permanganate (Mn(VII)) and MnO, and ferrate (Fe(VI)), as well as the transformation of organic pollutants including phenols, amines, polycyclic aromatic hydrocarbons (PAHs), organic dyes, pulp, and perfluoroalkyl acids (PFAAs) by Med. First, reaction kinetics and mechanisms of the oxidation of synthetic or natural mediators by these mild oxidants were summarized. Reactivity and pathways of synthetic Med including ABTS, ABTS, HBT or natural Med including phenoxy radicals and quinone-type compounds reacting with different organic pollutants were then discussed. Finally, the possibilities of engineering applications and new perspectives were assessed on the combinations of different types of mild oxidants with synthetic or natural mediators for the treatment of various organic pollutants.
Topics: Environmental Pollutants; Laccase; Manganese Compounds; Oxidants; Oxidation-Reduction; Oxides
PubMed: 33271411
DOI: 10.1016/j.watres.2020.116667 -
Environmental Science and Pollution... Nov 2022The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and...
The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and diversified surface functional groups. The biomaterial thermal stability was improved by Kraft black liquor, which increased the fixed carbon yield by 19.78% in an oxidant medium and 9.07% in an inert medium. Moreover, the presence of fixed carbon and char is positively related to the material flame retardant property. Additionally, impedance measurements were used to understand the physical phenomena occurring at the polymeric matrix's interface and the material's final properties. The biobased resin characterization and the considerable increase in the presence of micropollutants in surface and water bodies suggest the new biomaterial application in the adsorption process. Thus, its adsorption capacity toward several organic and inorganic micropollutants and its effectiveness in complex water matrices were evaluated. Methylene blue was used as a model compound to assess the influence of the resin composition on the adsorption capacity, and the type H isotherm indicates the high affinity of the biobased resin toward the micropollutant. The adsorption occurs in multilayer by intermolecular interaction and electrostatic forces. The amount of Kraft black liquor favored the adsorption, and the adsorption capacity was greater than 1250 mg g. When inorganic compounds were evaluated, the carboxyl and phenol groups favor the biomaterial affinity toward metal ions. Cu and Ni were completely removed from the contaminated water, and the adsorption capacity of the other inorganic compounds was: Pb (36.97 mg g), Al (22.17 mg g), Ba (12.76 mg g), Ag (33.85 mg g), and Fe (19.44 mg g). In contrast, the adsorption capacity of the organic micropollutants was: 2,4-D (3.09 mg g), diuron (5.89 mg g), atrazine (2.71 mg g), diclofenac (2.04 mg g), caffeine (5.79 mg g), acetaminophen (4.80 mg g), methylene Blue (106.66 mg g), and methyl orange (30.48 mg g). The results pointed that the adsorption efficiency of organic micropollutants increases with the distribution coefficient (logD), indicating the biobased resin affinity toward more lipophilic compounds and ionized species.
Topics: Water Purification; Water Pollutants, Chemical; Proanthocyanidins; Atrazine; Methylene Blue; Diclofenac; Acetaminophen; Caffeine; Diuron; Flame Retardants; Lead; Adsorption; Carbon; 2,4-Dichlorophenoxyacetic Acid; Water; Phenols; Oxidants; Biocompatible Materials; Kinetics
PubMed: 35091942
DOI: 10.1007/s11356-021-18250-3 -
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 -
Journal of Environmental Management Nov 2023Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity.... (Review)
Review
Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity. Innovative treatment and emerging technologies are being scrutinized to address the treatment of landfill leachate challenges. The leading target of this review was to examine the possibility of removing recalcitrant organic pollutants from landfill leachate by photocatalytic-based advanced oxidation processes. A summary of the systematic applicability of conventional treatment for landfill leachate is provided, with a focus on physico-chemical and biological processes. The biological treatment, such as aerobic and anaerobic digestion, is an excellent technique for treating highly concentrated organic pollutants in the wastewater. However, Leachate can scarcely be treated using conventional techniques since it is enriched with refractory organics and inorganic ions. It is clear from the literature review that none of the available combinations of physico-chemical and biological treatments are entirely relevant for the removal of recalcitrant organic pollutants from leachate. Recently, the photo-assisted TiO/ZnO oxidation has shown an excessively potential and feasible way to treat landfill leachate. TiO/ZnO photocatalysis is currently developing to treat recalcitrant organic pollutants from landfill leachate. The effect of operating parameters reveals that pH and temperature affect the reaction rate. The addition of oxidant HO to the TiO/ZnO suspension suggests that TiO leads to an increase in the rate of reaction when compared to ZnO. Photocatalytic remediation technique of landfill leachate would support the goal of environmental sustainability by greatly enhancing the effectiveness of treated leachate reutilization. In this review, the selection of the best photocatalytic treatment for leachate based on its systematic relevance and potential conditions, characteristics, cost-effectiveness, essential controlling, discharge limit, long-term environmental effects, and its future study perspectives are emphasized and discussed.
Topics: Waste Disposal, Fluid; Water Pollutants, Chemical; Hydrogen Peroxide; Zinc Oxide; Oxidation-Reduction
PubMed: 37619385
DOI: 10.1016/j.jenvman.2023.118794