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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 -
Chemosphere Oct 2023Biological nitrogen removal (BNR) is essential for the treatment of nitrogen-containing wastewater. However, the requirement for aeration and the addition of external... (Review)
Review
Biological nitrogen removal (BNR) is essential for the treatment of nitrogen-containing wastewater. However, the requirement for aeration and the addition of external carbon sources, resulting in greenhouse gas emissions and additional costs, are disadvantages of the traditional BNR process. Alternative technologies have been devised to overcome these drawbacks. Bioelectrochemical nitrogen removal (BENR) has been proposed for efficient nitrogen removal, demonstrating flexibility and versatility. BENR can be performed by combining nitrification, denitrification, anaerobic ammonium oxidation (ANAMMOX), or organic carbon oxidation. Bioelectrochemical-ANAMMOX (BE-ANAMMOX) is the most promising method for nitrogen removal, as it can directly convert NH to N and H in one step when the electrode is arranged as an electron acceptor. High-value-added hydrogen can potentially be recovered with efficient nitrogen removal using this concept, maximizing the benefits of BENR. Using alternative electron acceptors, such as electrodes and metal ions, for complete total nitrogen removal is a promising technology to substitute NO production from NH oxidation by aeration. However, the requirement of electron donors for NO reduction, low NH removal efficiency, and low competitiveness of exoelectrogenic bacteria still remain the main obstacles. The future direction for successful BENR should aim to achieve complete anaerobic NH oxidation without any electron acceptor and to maximize selectivity in H production. Therefore, the bioelectrochemical pathways and balances between efficient nitrogen removal and high-value-added chemical production should be further studied for carbon and energy neutralities.
Topics: Denitrification; Nitrogen; Bioreactors; Anaerobiosis; Oxidation-Reduction; Oxidants; Carbon; Ammonium Compounds; Sewage
PubMed: 37567277
DOI: 10.1016/j.chemosphere.2023.139776 -
Chemosphere Dec 2022Permanganate (Mn(VII)) is a widely used oxidant in water treatment, which can oxidize trace organic contaminants (TrOCs) and Mn(II). Interestingly, this study found that...
Permanganate (Mn(VII)) is a widely used oxidant in water treatment, which can oxidize trace organic contaminants (TrOCs) and Mn(II). Interestingly, this study found that presence of Mn(II) could accelerate the abatement of bisphenol A by Mn(VII) only under oxic condition. Herein, the effects of Mn(II) and dissolved oxygen (DO) on the abatement of TrOCs by Mn(VII) oxidation and the related mechanism were investigated. Results indicate that DO was involved in the Mn(VII)/Mn(II) reaction, with the reaction stoichiometry of Δ[Mn(VII)]:Δ[Mn(II)] determined to be 1:2 and 1:1.5 in the presence and absence of DO, respectively. Quenching and electron paramagnetic resonance tests verified that both superoxide radicals (O) and reactive Mn species contributed to the accelerated abatement of TrOCs (bisphenol A, methyl phenyl sulfoxide, and methyl phenyl sulfone) in the Mn(VII)/Mn(II) process. Specifically, O was produced through the one-electron reduction of DO and made an important contribution (32.4%-100%) to the abatement of selected TrOCs. This study reveals that Mn(II) could enhance TrOC abatement by Mn(VII) oxidation, and DO played a pivotal role in the Mn(VII)/Mn(II) process.
Topics: Benzhydryl Compounds; Oxidants; Oxygen; Phenols; Sulfones; Superoxides
PubMed: 36084823
DOI: 10.1016/j.chemosphere.2022.136321 -
Chemosphere Apr 2022Odor problems are challenging issues in water treatment. Advanced oxidation has a significant degradation effect on these odors; however, some issues, such as oxidant...
Odor problems are challenging issues in water treatment. Advanced oxidation has a significant degradation effect on these odors; however, some issues, such as oxidant residues and disinfection byproducts, exist in the use of advanced oxidation in actual water treatment. Because of the above issues, a combined advanced oxidation process has emerged-the UV/HO -biological activated carbon (BAC) process can play a strong oxidizing role in advanced oxidation and uses the physical adsorption and biological effects of activated carbon. However, there have been few studies on the odor degradation mechanism and characteristics of activated carbon biofilms in actual water treatment. This paper systematically studied the organic and odor substances removal effects and mechanism of a pilot combined UV/HO-BAC process. The results showed that UV/HO-BAC technology had a good removal effect on odor substances under long-term stable operation. The concentrations of geosmin (GSM) and 2-methylisoborneol (2-MIB) after systemic treatment were below 5 ng/L. The removal rates of DOC, UV and HO by the combined process were 53.60%, 73.08% and 60.20%, respectively. The results of full-scan determination of GSM and 2-MIB degradation by gas chromatography-mass spectrometry (GC-MS) were consistent with those of front-track analysis. The diversity, richness and evenness of microorganisms in the lower activated carbon layer were higher than those in the middle and upper activated carbon layers. The greater the difference in the carbon layer height was, the greater the difference in the biological community structure.
Topics: Charcoal; Drinking Water; Hydrogen Peroxide; Odorants; Water Pollutants, Chemical; Water Purification
PubMed: 34982966
DOI: 10.1016/j.chemosphere.2021.133419 -
Environmental Science and Pollution... Jan 2021Discharge plasma technology is a new advanced oxidation technology for water treatment, which includes the effects of free radical oxidation, high energy electron... (Review)
Review
Discharge plasma technology is a new advanced oxidation technology for water treatment, which includes the effects of free radical oxidation, high energy electron radiation, ultraviolet light hydrolysis, and pyrolysis. In order to improve the energy efficiency in the plasma discharge processes, many efforts have been made to combine catalysts with discharge plasma technology. Some heterogeneous catalysts (e.g., activated carbon, zeolite, TiO) and homogeneous catalysts (e.g., Fe/Fe, etc.) have been used to enhance the removal of pollutants by discharge plasma. In addition, some reagents of in situ chemical oxidation (ISCO) such as persulfate and percarbonate are also discussed. This article introduces the research progress of the combined systems of discharge plasma and catalysts/oxidants, and explains the different reaction mechanisms. In addition, physical and chemical changes in the plasma catalytic oxidation system, such as the effect of the discharge process on the catalyst, and the changes in the discharge state and solution conditions caused by the catalysts/oxidants, were also investigated. At the same time, the potential advantages of this system in the treatment of different organic wastewater were briefly reviewed, covering the degradation of phenolic pollutants, dyes, and pharmaceuticals and personal care products. Finally, some suggestions for future water treatment technology of discharge plasma are put forward. This review aims to provide researchers with a deeper understanding of plasma catalytic oxidation system and looks forward to further development of its application in water treatment.
Topics: Catalysis; Oxidants; Oxidation-Reduction; Pharmaceutical Preparations; Plasma; Wastewater; Water Pollutants, Chemical
PubMed: 33105014
DOI: 10.1007/s11356-020-11222-z -
Journal of Environmental Management Dec 2021Treatment of organic peroxide-containing chemical industry wastewater by oxidation methods and recovery of water by the adsorption and nanofiltration (NP010) methods...
Treatment of organic peroxide-containing chemical industry wastewater by oxidation methods and recovery of water by the adsorption and nanofiltration (NP010) methods were investigated in this study. The COD and TOC removal rates were obtained as 72.8% and 58.0% in Fenton oxidation and were improved to 78.8% and 59.2% using photo-Fenton oxidation in the same conditions after 5 h of oxidation, respectively. The Fenton-treated wastewater was passed through nanofiltration to remove the organics and recover of the wastewater. The maximum COD removal efficiency of the NP010 membrane varied between 25% and 30% at all pH values. At low and high pH values (pH: 2.5 and pH: 11), as the filtration time increased, the COD removal efficiencies increased, and the highest COD removal efficiencies were obtained in the 180th and 210th minutes. The increase in the COD removal over time at low and high pH was related to the thickness of the filter layer and surface load balance accumulated on the filter surface. By Fenton oxidation coupling with adsorption, 81% of COD (decreased from 10,055 mg/L to 1906 mg/L) and 75.2% of TOC (decreased from 2597 mg/L to 645.4 mg/L) removal could be obtained, while 83.3% of COD (decreased from 9978 mg/L to 1664 mg/L) and 71.1% of TOC (decreased from 2597 mg/L to 750 mg/L) removal could be achieved using Fenton oxidation coupling with nanofiltration (P: 4 bar, pH: 11). In nanofiltration, the filtrate amounts were measured as 41.11 L/m.h and 38.33 L/m.h, respectively, at 4 bar and 6 bar of filter pressure and 30 min of filtration time. The increase in filtration time and filter pressure caused a decrease in the amount of the filtrate due to the rapid clogging of the filter pores.
Topics: Adsorption; Hydrogen Peroxide; Oxidation-Reduction; Peroxides; Waste Disposal, Fluid; Wastewater; Water; Water Pollutants, Chemical
PubMed: 34467860
DOI: 10.1016/j.jenvman.2021.113557 -
Journal of Hazardous Materials Oct 2022Sulfite has been used as a classic reductant for the dehalogenation and reduction of organic compounds for a long time, it is recently deemed as a promising alternative...
Sulfite has been used as a classic reductant for the dehalogenation and reduction of organic compounds for a long time, it is recently deemed as a promising alternative (for persulfate) to generate sulfate radical for wastewater treatment due to its low price and eco-toxicity. In contrast with the enormous work developed in the field of tetracycline (TC) degradation via PMS activization, sulfite activization could play a important role in TC degradation but there is only very few available reports in this area. Herein, the novel and efficient CoNHs nanocatalyst is designed and developed, via immobilization of hydrangea-shaped CoO nanoparticles onto graphitic carbon nanosheet (GCN), for the degradation of tetracycline via sulfite activation. The detailed characterizations have confirmed that CoNHs possesses a nanohydrangea-shaped structure with high microporosity. The comparison with other supports (such as CeO and MoS), CoNHs provides the highest degradation efficiency in TC degradation, due to the synergistic effect between CoO and GCN. Free radical quenching experiments and EPR analysis confirm that SO• and O• are major reactive oxygen species in the CoNHs/sulfite system. This work could provide a simple, economical and durable cobalt-based catalyst for organic wastewater treatment via sulfite activation.
Topics: Carbon; Cobalt; Graphite; Organic Chemicals; Oxides; Peroxides; Sulfites; Tetracycline
PubMed: 35870208
DOI: 10.1016/j.jhazmat.2022.129618 -
Angewandte Chemie (International Ed. in... May 2022This work reports an aqueous dye-sensitized photoelectrochemical cell (DSPEC) capable of oxidizing glycerol (an archetypical biobased compound) coupled with H...
This work reports an aqueous dye-sensitized photoelectrochemical cell (DSPEC) capable of oxidizing glycerol (an archetypical biobased compound) coupled with H production. We employed a mesoporous TiO photoanode sensitized with the high potential thienopyrroledione-based dye AP11, encased in an acetonitrile-based redox-gel that protects the photoanode from degradation by aqueous electrolytes. The use of the gel creates a biphasic system with an interface at the organic (gel) electrode and aqueous anolyte. Embedded in the acetonitrile gel is 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), acting as both a redox-mediator and a catalyst for oxidative transformations. Upon oxidation of TEMPO by the photoexcited dye, the in situ generated TEMPO shuttles through the gel to the acetonitrile-aqueous interface, where it acts as an oxidant for the selective conversion of glycerol to glyceraldehyde. The introduction of the redox-gel layer affords a 10-fold increase in the conversion of glycerol compared to the purely aqueous system. Our redox-gel protected photoanode yielded a stable photocurrent over 48 hours of continuous operation, demonstrating that this DSPEC is compatible with alkaline aqueous reactions.
Topics: Acetonitriles; Coloring Agents; Cyclic N-Oxides; Glycerol; Oxidation-Reduction; Photosynthesis; Solar Energy; Water
PubMed: 35266261
DOI: 10.1002/anie.202200175 -
International Journal of Molecular... Dec 2023Dinitrosyl iron complexes (DNICs) are important physiological derivatives of nitric oxide. These complexes have a wide range of biological activities, with antioxidant...
Dinitrosyl iron complexes (DNICs) are important physiological derivatives of nitric oxide. These complexes have a wide range of biological activities, with antioxidant and antiradical ones being of particular interest and importance. We studied the interaction between DNICs associated with the dipeptide L-carnosine or serum albumin and prooxidants under conditions mimicking oxidative stress. The ligands of these DNICs were histidine residues of carnosine or His39 and Cys34 in bovine serum albumin. Carnosine-bound DNICs reduced the level of piperazine free radicals in the reaction system containing -butyl hydroperoxide (-BOOH), bivalent iron ions, a nitroxyl anion donor (Angeli's salt), and HEPES buffer. The ability of carnosine DNICs to intercept organic free radicals produced from -BOOH decay could lead to this effect. In addition, carnosine DNICs reacted with the superoxide anion radical (O) formed in the xanthine/xanthine oxidase enzymatic system. They also reduced the oxoferryl form of the heme group formed in the reaction of myoglobin with -BOOH. DNICs associated with serum albumin were found to be rapidly destroyed in a model system containing metmyoglobin and t-BOOH. At the same time, these protein DNICs inhibited the -BOOH-induced oxidative degradation of coenzymes Q and Q in rat myocardial homogenate. The possible mechanisms of the antioxidant and antiradical action of the DNICs studied and their role in the metabolism of reactive oxygen and nitrogen species are discussed.
Topics: Rats; Animals; Antioxidants; Histidine; Carnosine; Nitrogen Oxides; Iron; Nitric Oxide; Free Radicals; Superoxides; Oxygen; Serum Albumin
PubMed: 38139065
DOI: 10.3390/ijms242417236 -
International Journal of Biological... May 2023Improving the adsorption kinetics of metal-oxide catalysts is critical for the enhancement of catalytic performance in heterogeneous catalytic oxidation reactions....
Improving the adsorption kinetics of metal-oxide catalysts is critical for the enhancement of catalytic performance in heterogeneous catalytic oxidation reactions. Herein, based on the biopolymer pomelo peels (PP) and metal-oxide catalyst manganese oxide (MnO), an adsorption-enhanced catalyst (MnO-PP) was constructed for catalytic organic dyes oxidative-degradation. MnO-PP shows excellent methylene blue (MB) and total carbon content (TOC) removal efficiency of 99.5 % and 66.31 % respectively, and keeps the long-lasting stable dynamic degradation efficiency during 72 h based on the self-built continuous single-pass MB purification device. The chemical structure similarity and negative-charge polarity sites of the biopolymer PP improve the adsorption kinetics of organic macromolecule MB, and construct the adsorption-enhanced catalytic oxidation microenvironment. Meanwhile, the adsorption-enhanced catalyst MnO-PP obtains lower ionization potential and O adsorption energy to promote the continuous generation of active substance (O*, OH*) for the further catalytic oxidation of adsorbed MB molecules. This work explored the adsorption-enhanced catalytic oxidation mechanism for the degradation of organic pollutants, and provided a feasible technical idea for designing adsorption-enhanced catalysts for the long-lasting efficient removal of organic dyes.
Topics: Manganese; Adsorption; Porosity; Oxides; Oxidation-Reduction; Catalysis; Coloring Agents
PubMed: 36966855
DOI: 10.1016/j.ijbiomac.2023.124152