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Indoor Air Jun 2022The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper...
The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude on indoor photolysis rates and hence indoor air chemistry. Switching from an LED to an uncovered fluorescent tube light increased predicted indoor hydroxyl radical concentrations by ~13%. However, moving from glass that transmitted outdoor light at wavelengths above 380 nm to one that transmitted sunlight above 315 nm led to an increase in predicted hydroxyl radicals of more than 400%. For our studied species, including ozone, nitrogen oxides, nitrous acid, formaldehyde, and hydroxyl radicals, the latter were most sensitive to changes in indoor photolysis rates. Concentrations of nitrogen dioxide and formaldehyde were largely invariant, with exchange with outdoors and internal deposition controlling their indoor concentrations. Modern lights such as LEDs, together with low transmission glasses, will likely reduce the effects of photolysis indoors and the production of potentially harmful species. Research is needed on the health effects of different indoor air mixtures to confirm this conclusion.
Topics: Air Pollutants; Air Pollution, Indoor; Formaldehyde; Hydroxyl Radical; Nitrous Acid; Photolysis
PubMed: 35762241
DOI: 10.1111/ina.13054 -
Molecules (Basel, Switzerland) Sep 2021This study investigated the direct and indirect photochemical degradation of citalopram (CIT), a selective serotonin reuptake inhibitor (SSRI), under natural and...
This study investigated the direct and indirect photochemical degradation of citalopram (CIT), a selective serotonin reuptake inhibitor (SSRI), under natural and artificial solar radiation. Experiments were conducted in a variety of different operating conditions including Milli-Q (MQ) water and natural waters (lake water and municipal WWT effluent), as well as in the presence of natural water constituents (organic matter, nitrate and bicarbonate). Results showed that indirect photolysis can be an important degradation process in the aquatic environment since citalopram photo-transformation in the natural waters was accelerated in comparison to MQ water both under natural and simulated solar irradiation. In addition, to investigate the decontamination of water from citalopram, TiO-mediated photocatalytic degradation was carried out and the attention was given to mineralization and toxicity evaluation together with the identification of by-products. The photocatalytic process gave rise to the formation of transformation products, and 11 of them were identified by HPLC-HRMS, whereas the complete mineralization was almost achieved after 5 h of irradiation. The assessment of toxicity of the treated solutions was performed by Microtox bioassay () and in silico tests showing that citalopram photo-transformation involved the formation of harmful compounds.
Topics: Catalysis; Citalopram; Photochemical Processes; Photolysis; Water
PubMed: 34500774
DOI: 10.3390/molecules26175331 -
The Journal of Organic Chemistry Jan 2022Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we...
Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (-COCN-) attached to position 5' or 6' of the pendant phenyl rings. For that, the mixture of 5'- or 6'-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones ArCOCNAr. The high performance liquid chromatography (HPLC) separation gave four individual regioisomers of ArCOCNAr. Photolysis of the model compound─CHCOCNCH─in aqueous acetonitrile at pH 7.3 and under irradiation with 365 nm light provided diphenylacetic acid amide (Wolff rearrangement). However, under the same conditions, ArCOCNAr gave mainly α-diketones ArCOCOAr. The migration ability of the very bulky dye residues was low, and the Wolff rearrangement did not occur. We observed only moderate fluorescence increase, which may be explained by the insufficient quenching ability of diazoketone bridge (-COCN-) and its transformation into another (weaker) quencher, 1,2-diarylethane-1,2-dione.
Topics: Fluorescent Dyes; Photolysis; Rhodamines; Spectrometry, Fluorescence; Water
PubMed: 34919387
DOI: 10.1021/acs.joc.1c01721 -
The Science of the Total Environment Aug 2022This study aimed to assess the possibility of using solar light-driven photolysis and TiO-based photocatalysis to remove (1) antibiotic residues, (2) their...
This study aimed to assess the possibility of using solar light-driven photolysis and TiO-based photocatalysis to remove (1) antibiotic residues, (2) their transformation products (TPs), (3) antibiotic resistance determinants, and (4) genes identifying the indicator bacteria in a treated wastewater (secondary effluent). 16 antimicrobials belonging to the different classes and 45 their transformation by-products were selected for the study. The most susceptible to photochemical decomposition was tetracycline, which was completely removed in the photocatalysis process and in more than 80% in the solar light-driven photolysis. 83.8% removal (on average) was observed using photolysis and 89.9% using photocatalysis in the case of the tested genes, among which the genes sul1, uidA, and intI1 showed the highest degree of removal by both methods. The study revealed that applied methods promisingly remove the tested antibiotics, their TPs and genes even in such a complex matrix including treated wastewater and photocatalysis process had a higher removal efficiency of antibiotics, TPs and genes tested. Moreover, the high percentage removal of the intI1 gene (>93%) indicates the possibilities of use of the solar light-driven photolysis and TiO-based photocatalysis in minimizing the antibiotic resistance genes transfer by mobile genetic elements.
Topics: Anti-Bacterial Agents; Catalysis; Drug Resistance, Microbial; Photolysis; Titanium; Wastewater; Water Pollutants, Chemical
PubMed: 35469868
DOI: 10.1016/j.scitotenv.2022.155447 -
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 -
Molecules (Basel, Switzerland) Dec 2022Recent studies on the removal of pollutants via adsorption include the use of carbon-based adsorbents, due to their high porosity and large surface area; however, such...
Recent studies on the removal of pollutants via adsorption include the use of carbon-based adsorbents, due to their high porosity and large surface area; however, such materials lack photoactive properties. This study evaluates the synergistic effect of integrated mesoporous carbon xerogel (derived from resorcinol formaldehyde) and titanium dioxide (TiO) for combined adsorption and photodegradation application. The complex formed between carbon xerogel and TiO phase was investigated through FTIR, proving the presence of a Ti-O-C chemical linkage. The physicochemical properties of the synthesised adsorbent-photocatalyst were probed using FESEM, BET analysis and UV-Vis analysis. The kinetics, equilibrium adsorption, effect of pH, and effect of adsorbent dosage were investigated. The expansion of the absorbance range to the visible range was verified, and the corresponding band gap evaluated. These properties enabled a visible light response when the system was exposed to visible light post adsorption. Hence, an assistive adsorption-photodegradation phenomenon was successfully executed. The adsorption performance exhibited 85% dye degradation which improved to 99% following photodegradation. Further experiments showed the reduction of microorganisms under visible light, where no microbial colonies were observed after treatment, indicating the potential application of these composite materials.
Topics: Environmental Pollutants; Photolysis; Titanium; Adsorption; Carbon; Catalysis
PubMed: 36500576
DOI: 10.3390/molecules27238483 -
Molecules (Basel, Switzerland) Oct 2022The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS) nanomaterials are attracting attention in... (Review)
Review
The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS) nanomaterials are attracting attention in various fields, such as energy, hydrogen production, and water decontamination. This review provides an overview of the recent developments in MoS-based nanomaterials for water treatment via adsorption and photodegradation. Primary attention is given to the structure, properties, and major methods for the synthesis and modification of MoS, aiming for efficient water-contaminant removal. The combination of MoS with other components results in nanocomposites that can be separated easily or that present enhanced adsorptive and photocatalytic properties. The performance of these materials in the adsorption of heavy metal ions and organic contaminants, such as dyes and drugs, is reviewed. The review also summarizes current progress in the photocatalytic degradation of various water pollutants, using MoS-based nanomaterials under UV-VIS light irradiation. MoS-based materials showed good activity after several reuse cycles and in real water scenarios. Regarding the ecotoxicity of the MoS, the number of studies is still limited, and more work is needed to effectively evaluate the risks of using this nanomaterial in water treatment.
Topics: Photolysis; Adsorption; Molybdenum; Water Pollutants; Water Pollutants, Chemical; Nanocomposites; Metals, Heavy; Coloring Agents; Hydrogen
PubMed: 36296375
DOI: 10.3390/molecules27206782 -
Molecules (Basel, Switzerland) Mar 2017Molecular Modeling methods play a very important role in TiO₂ photocatalysis. Recent advances in TiO₂ photocatalysis have produced a number of interesting surface... (Review)
Review
Molecular Modeling methods play a very important role in TiO₂ photocatalysis. Recent advances in TiO₂ photocatalysis have produced a number of interesting surface phenomena, reaction products, and various novel visible light active photocatalysts with improved properties. Quantum mechanical calculations appear promising as a means of describing the mechanisms and the product distributions of the photocatalytic degradation reactions of organic pollutants in both gas and aqueous phases. Since quantum mechanical methods utilize the principles of particle physics, their use may be extended to the design of new photocatalysts. This review introduces molecular modeling methods briefly and emphasizes the use of these methods in TiO₂ photocatalysis. The methods used for obtaining information about the degradabilities of the pollutant molecules, predicting reaction mechanisms, and evaluating the roles of the dopants and surface modifiers are explained.
Topics: Catalysis; Models, Molecular; Molecular Dynamics Simulation; Photolysis; Quantum Theory; Surface Properties; Titanium
PubMed: 28358308
DOI: 10.3390/molecules22040556 -
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 -
Journal of the American Chemical Society Jul 2022Photolabile protecting groups (PPGs) enable the precise activation of molecular function with light in many research areas, such as photopharmacology, where remote...
Photolabile protecting groups (PPGs) enable the precise activation of molecular function with light in many research areas, such as photopharmacology, where remote spatiotemporal control over the release of a molecule is needed. The design and application of PPGs in recent years have particularly focused on the development of molecules with high molar absorptivity at long irradiation wavelengths. However, a crucial parameter, which is pivotal to the efficiency of uncaging and which has until now proven highly challenging to improve, is the photolysis quantum yield (QY). Here, we describe a novel and general approach to greatly increase the photolysis QY of heterolytic PPGs through stabilization of an intermediate chromophore cation. When applied to coumarin PPGs, our strategy resulted in systems possessing an up to a 35-fold increase in QY and a convenient fluorescent readout during their uncaging, all while requiring the same number of synthetic steps for their preparation as the usual coumarin systems. We demonstrate that the same QY engineering strategy applies to different photolysis payloads and even different classes of PPGs. Furthermore, analysis of the DFT-calculated energy barriers in the first singlet excited state reveals valuable insights into the important factors that determine photolysis efficiency. The strategy reported herein will enable the development of efficient PPGs tailored for many applications.
Topics: Cations; Coumarins; Photolysis
PubMed: 35775744
DOI: 10.1021/jacs.2c04262