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Water Science and Technology : a... Nov 2023The effect of carboxyl and hydroxyl groups attached to the benzene ring on the photodegradation of anthracene (Ant) and pyrene (Pyr) in ice was investigated. The present...
The effect of carboxyl and hydroxyl groups attached to the benzene ring on the photodegradation of anthracene (Ant) and pyrene (Pyr) in ice was investigated. The present study aims to explore the inhibition mechanism of five dissolved organic matter (DOM) model compounds' materials such as benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, and 3-phenyl propionic acid on the degradation of Ant and Pyr in ice. The photodegradation rate of Ant and Pyr were 50.33 and 37.44% in ice, with the photodegradation rate of Ant being greater than that of Pyr. The five DOM model compounds inhibited the photolysis of Ant and Pyr, and the influence mechanism on the photodegradation of Ant and Pyr depended upon the types and positions of functional groups on the benzene. Among them, the structure in which the carboxyl group was directly connected to the benzene ring and carboxyl was located at the ortho position of a hydroxy group had a strong inhibitory effect on the photodegradation of Ant and Pyr. Light-screening effects and quenching effects were the main inhibiting mechanism, and the binding ability of DOM model compounds material and PAHs is dominantly correlated with its inhibiting effect.
Topics: Polycyclic Aromatic Hydrocarbons; Ice; Photolysis; Benzene
PubMed: 38017682
DOI: 10.2166/wst.2023.353 -
Ecotoxicology and Environmental Safety Sep 2023Glyphosate is the most widely used herbicide in global agricultural cultivation. However, little is known about the environmental risks associated with its migration and...
Glyphosate is the most widely used herbicide in global agricultural cultivation. However, little is known about the environmental risks associated with its migration and transformation. We conducted light irradiation experiments to study the dynamics and mechanism of photodegradation of glyphosate in ditches, ponds and lakes, and evaluated the effect of glyphosate photodegradation on algae growth through algae culture experiments. Our results showed that glyphosate in ditches, ponds and lakes could undergo photochemical degradation under sunlight irradiation with the production of phosphate, and the photodegradation rate of glyphosate in ditches could reach 86% after 96 h under sunlight irradiation. Hydroxyl radicals (•OH) was the main reactive oxygen species (ROS) for glyphosate photodegradation, and its steady-state concentrations in ditches, ponds and lakes were 6.22 × 10, 4.73 × 10, and 4.90 × 10 M. The fluorescence emission-excitation matrix (EEM) and other technologies further indicated that the humus components in dissolved organic matter (DOM) and nitrite were the main photosensitive substances producing •OH. In addition, the phosphate generated by glyphosate photodegradation could greatly promote the growth of Microcystis aeruginosa, thereby increasing the risk of eutrophication. Thus, glyphosate should be scientifically and reasonably applied to avoid environmental risks.
Topics: Photolysis; Water; Sunlight; Water Pollutants, Chemical; Phosphates; Glyphosate
PubMed: 37418942
DOI: 10.1016/j.ecoenv.2023.115211 -
Unveiling the Mechanism of Photodamage to Sphingolipid Molecules via Laser Flash Photolysis and EPR.Photochemistry and Photobiology 2023Sphingolipids are involved in the maintenance of the skin barrier function and regulate cellular processes of keratinocytes. The work reported here is designed to...
Sphingolipids are involved in the maintenance of the skin barrier function and regulate cellular processes of keratinocytes. The work reported here is designed to uncover details of the mechanism of damage to such lipids by UV radiation. Our approach employs laser flash photolysis and electron paramagnetic resonance (EPR) spectrometry to explore the mechanism of the decay reactions, and to determine the associated kinetic parameters. To interpret our experiments, we computed both excitation energies and EPR parameters of radicals formed during photolysis. Employing the spin-trap EPR method confirmed the formation of both carbon- and nitrogen-centered radicals. Thus, we can conclude that the photodecomposition of sphingolipids and their analogues proceeds by Norrish type I reactions with the formation of both nitrogen-centered and alkyl radicals.
Topics: Electron Spin Resonance Spectroscopy; Photolysis; Lasers; Nitrogen; Free Radicals
PubMed: 36943199
DOI: 10.1111/php.13804 -
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 -
The Science of the Total Environment Mar 2024We use the Community Multiscale Air Quality (CMAQv5.4) model to examine the potential impact of particulate nitrate (pNO) photolysis on air quality over the Northern...
We use the Community Multiscale Air Quality (CMAQv5.4) model to examine the potential impact of particulate nitrate (pNO) photolysis on air quality over the Northern Hemisphere. We estimate the photolysis frequency of pNO by scaling the photolysis frequency of nitric acid (HNO) with an enhancement factor that varies between 10 and 100 depending on pNO and sea-salt aerosol concentrations and then perform CMAQ simulations without and with pNO photolysis to quantify the range of impacts on tropospheric composition. The photolysis of pNO produces gaseous nitrous acid (HONO) and nitrogen dioxide (NO) over seawater thereby increasing atmospheric HONO and NO mixing ratios. HONO subsequently undergoes photolysis, producing hydroxyl radicals (OH). The increase in NO and OH alters atmospheric chemistry and enhances the atmospheric ozone (O) mixing ratio over seawater, which is subsequently transported to downwind continental regions. Seasonal mean model O vertical column densities without pNO photolysis are lower than the Ozone Monitoring Instrument (OMI) retrievals, while the column densities with the pNO photolysis agree better with the OMI retrievals of tropospheric O burden. We compare model O mixing ratios with available surface observed data from the U.S., Japan, the Tropospheric Ozone Assessment Report - Phase II, and OpenAQ; and find that the model without pNO photolysis underestimates the observed data in winter and spring seasons and the model with pNO photolysis improves the comparison in both seasons, largely rectifying the pronounced underestimation in spring. Compared to measurements from the western U.S., model O mixing ratios with pNO photolysis agree better with observed data in all months due to the persistent underestimation of O without pNO photolysis. Compared to the ozonesonde measurements, model O mixing ratios with pNO photolysis also agree better with observed data than the model O without pNO photolysis.
PubMed: 38281631
DOI: 10.1016/j.scitotenv.2024.170406 -
Environmental Pollution (Barking, Essex... Mar 2024The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for...
The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for non-target organisms. Phototransformation is one of the most significant transformation processes, which is directly related to NNIs exposure and environmental risks. In this study, the photodegradation of dinotefuran (DIN, 1-Methyl-2-nitro-3-(tetrahydro-3-furanylmethyl)-guanidine), one of the most promising NNIs, was conducted under irritated light in the presence of Cl, DOM along with the effect of pH and initial concentration. The findings demonstrated that in ultra-pure (UP) water, the photolysis rate constants (k) of DIN rose with increasing initial concentration. Whereas, in tap water, at varied pH levels, and in the presence of Cl-, the outcomes were reversed. At the same time, lower concentration of DOM promoted DIN photolysis processes due to the production of reactive oxygen species, while higher concentrations of DOM inhibited the photolysis by the predominance of light shielding effects. The singlet oxygen (O) was produced in the photolysis processes of DIN with Cl and DOM, which was confirmed by electron spin resonance (EPR) analysis. Four main photolysis products and three intermediates were identified by UPLC-Q-Exactive Orbitrap MS analysis. The possible photodegradation pathways of DIN were proposed including the oxidation by O, reduction and hydrolysis after the removal of nitro group from parent compounds. This study expanding our understanding of transformation behavior and fate of NNIs in the aquatic environment, which is essential for estimating their environmental risks.
Topics: Photolysis; Neonicotinoids; Water; Guanidines; Kinetics; Water Pollutants, Chemical; Nitro Compounds
PubMed: 38219898
DOI: 10.1016/j.envpol.2024.123352 -
Environmental Science and Pollution... Mar 2024Bendazone (BNTE) is an herbicide and a highly concerned pollutant in aquatic environments. Understanding the photochemical behavior of BNTE in water is crucial for...
Bendazone (BNTE) is an herbicide and a highly concerned pollutant in aquatic environments. Understanding the photochemical behavior of BNTE in water is crucial for evaluating its photochemical conversion process in aquatic environments. This study analyzed the direct photolysis and indirect photolysis pathways of two dissociated forms of BNTE in water through density functional theory and time-dependent density functional theory method. The results show that the reaction types of indirect photolysis of BNTE with free radicals (•OH, •SO, and •CO) are OH addition, SO addition, and CO addition. In the process of indirect photolysis of BNTE and free radicals, the photolysis of •OH and BNTE was the easiest, followed by •SO. In addition, the active site of BNTE reacting with •OH is C8, and the active site of BNTE reacting with •SO is C10. However, the photolysis effect of •CO on BNTE is very small, indicating that •CO in water plays a secondary role in the indirect photolysis of BNTE. In the direct photolysis of BNTE, N1-C6 bond breaking is difficult to occur spontaneously in the environment due to its high endothermic property and energy barrier. The direct photolysis pathway of BNTE involves the break of the N1-S2/S2-N3/N3-C12 bond. In addition, the ecological toxicity evaluation showed that toxicity of most of the degradation products were reduced, but the toxicity level was still maintained at a harmful level. Our findings provide the photochemical fate of BNTE in aquatic environments and will help to more accurately understand their photochemical conversion mechanisms in the environment.
Topics: Photolysis; Water; Water Pollutants, Chemical; Kinetics; Free Radicals
PubMed: 38353814
DOI: 10.1007/s11356-024-32315-z -
The Science of the Total Environment Jun 2024Microplastics (MPs) and persistent pollutants (POPs) are new pollutants that are extensively studied worldwide. To fill the gaps that the degradation processes and...
Investigation of the photolysis process of benzo(a)anthracene (BaA) on polyvinyl chloride (PVC) and polystyrene (PS) microplastics: Plastics aging effect, transformation products and toxicity assessment.
Microplastics (MPs) and persistent pollutants (POPs) are new pollutants that are extensively studied worldwide. To fill the gaps that the degradation processes and mechanisms of polycyclic aromatic hydrocarbons (PAHs) on the surface of most MPs are still unclear, the photochemical transformation of benzo(a)anthracene (BaA) on polyvinyl chloride (PVC) MPs and polystyrene (PS) MPs in water were investigated and compared. The photolysis of BaA on the surface of PS in water proceeded easier than that on PVC within the 48 h irradiation period, with the pseudo-first-order rate constant of 0.0489 min and 0.0181 min, respectively, which can be ascribed to the smaller particle size and more OH production of PS MPs. Due to the light competition between the chromophore and BaA as well as the light-shielding effect, aged MPs showed an inhibitory effect on the degradation of BaA compared with pristine MPs. For BaA/PVC MPs system, the degradation of BaA in real water was not significantly affected by coexisting ions and humic acid (HA) (p < 0.05), while slight inhibitory effect on the degradation of BaA appeared for PS MPs in different water matrices (UP: 86.97 %, YR: 84.47 %, PR: 81.42 % and HR: 83.21 %). According to the electron paramagnetic resonance (EPR) test, quenching experiment and probe experiment, the relative contribution of direct photolysis (PVC: 82.02 %; PS: 69.54 %) and indirect photolysis (PVC: 17.98 %; PS: 30.46 %) was confirmed. A total of 14 products were identified, and the product types were not affected by plastics aging. The results of the toxicity assessment indicated that although some intermediate products remained toxic to aquatic organisms, the toxicity of most products was lower than that of BaA. This study provides new insights into the environmental fate of PAHs and the role of MPs in the photolysis process of contaminants in surface water.
PubMed: 38636850
DOI: 10.1016/j.scitotenv.2024.172394 -
Environmental Science and Pollution... Sep 2023The novel photocatalyst of FeO@SiO/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM,...
The novel photocatalyst of FeO@SiO/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM, XRD, FTIR, and N adsorption-desorption analyses. The photocatalytic activity of nanocomposite was evaluated in comparison with other particles as well as adsorption and photolysis processes. The effect of operating parameters showed that the complete degradation of penicillin G (PNG) can be provided at a photocatalyst dosage of 0.6 g/L, radiation intensity of 36 W, pH of 5, and time of 60 min. In the optimum condition, 84% TOC removal was attained and the BOD/COD rate for the treated effluent was above 0.4, which was representative of the high biodegradability of the treated effluent compared to the raw sample. The findings of energy consumption showed that PNG can be easily and effectively treated by the photocatalytic process based on magnetic MIL-101(Fe) with electrical energy per order between 10 and 20.87 kWh/m. Due to the excellent interaction between the MIL-101(Fe) and FeO@SiO/PAEDTC, the photocatalyst stability test showed a recyclability of the particles for 5 consecutive reaction cycles with a minimum reduction of 7%. Solution treated with photocatalyst under UV and visible light sources explained that the toxicity of the effluent after treatment is significantly reduced with the growth of Escherichia coli. Scavenging experiments showed that OH radical and hole (h) are the main agents in degrading PNG to CO, HO, and biodegradable and low-toxicity products. Finally, the findings of the diagnostic analysis and comparative experiments proved that with the interaction of FeO@SiO, NH, and MIL-101(Fe), a lower band gap can be prepared for more absorption of photons and pollutant and also more and faster production of active radicals.
Topics: Silicon Dioxide; Light; Metal-Organic Frameworks; Photolysis; Catalysis
PubMed: 37620704
DOI: 10.1007/s11356-023-29283-1 -
Ying Yong Sheng Tai Xue Bao = the... Aug 2023Humus is a specific kind of organic matter widely distributed in soils. The characteristics of humus have significant impacts on the fate of pollutants in the...
Humus is a specific kind of organic matter widely distributed in soils. The characteristics of humus have significant impacts on the fate of pollutants in the environment. In this study, we examined the effects of fertilization modes from rice rotation systems on the contents, spectral properties, photochemical activity, and photosensitization of quinclorac (QNC) of humic (HA) and fulvic acids (FA). The results showed that under the rice-vegetable rotation system, organic fertilizer treatment decreased the humification degree and molecular weight of HA, but increased the number of oxygen-containing functional groups and the abilities of photoproducing hydroxyl radical (HO·), singlet oxygen (O) and photosensitizing QNC, compared with chemical fertilizer treatment. Under organic fertilization mode, the molecular weight of FA was increased, but the number of redox functional groups and the abilities of photoinducing HO· and O and photosensitizing QNC were decreased. Under rice-shrimp cultivation system, organic-inorganic fertilizer treatment increased the humification degree, molecular weight, number of redox functional groups and oxygen-containing functional groups, and O photogeneration of HA, but decreased the abilities of photoproducing HO· and photosensitizing QNC, as compared with chemical fertilizer treatment. The humification degree and molecular weight of FA under organic-inorganic fertilization mode were increased, while the abilities of photoproducing HO· and O and photosensitizing QNC were decreased. In conclusion, organic fertilization could enhance the photochemical activity and photosensitizing efficiency of humus, and further promote the photodegradation of QNC in the environment.
Topics: Photolysis; Soil; Fertilizers; Oryza; Oxygen; Fertilization
PubMed: 37681382
DOI: 10.13287/j.1001-9332.202308.014