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Environmental Monitoring and Assessment Aug 2023Keeping in view the toxicity of the Rhodamine B, the present study is designed to remediate the water loaded with toxic dyes using gallium oxide and gallium hybrids as...
Keeping in view the toxicity of the Rhodamine B, the present study is designed to remediate the water loaded with toxic dyes using gallium oxide and gallium hybrids as photocatalyst. Precipitation coupled with sonochemical method is adopted for the synthesis of gallium oxide while the post grafting method is adopted for the synthesis of gallium hybrids with the indole and its derivatives. FTIR spectra showed the characteristic absorption bands of gallium oxide and gallium hybrids at 400-700 cm and 1400-1600 cm. SEM and XRD showed the micro-sized rectangular rod-shaped gallium oxide with rhombohedral geometry. The average crystallite size of gallium hybrids was 26-32 nm calculated using the Debye Scherrer and Williamson-Hal models. The BET isotherm of gallium hybrids revealed the adsorption type-IV and hysteresis loop (H3) proposing multilayer and mesoporous structures with increase in surface area from 26 m/g of gallium oxide to 31 m/g of gallium-indole, 35 m/g of gallium-methyl indole, and 37 m/g of gallium-carboxylic indole. XPS showed the presence of gallium (3-14%), oxygen (28-32%), nitrogen (23-46%), and carbon (9-46%). The gallium oxide and gallium hybrids showed 47-72% optimum degradation of Rhodamine B under 2 h of illumination at pH 7 and 0.03 mg/L. The degradation rate followed a Langmuir-Hinshelwood model with R > 0.9.
Topics: Photolysis; Environmental Monitoring; Gallium; Indoles
PubMed: 37642762
DOI: 10.1007/s10661-023-11683-y -
The Journal of Organic Chemistry Jul 2023The photolysis of 2-azidofluorene in solid argon at 3 K results in the formation of 2-fluorenylnitrene. The nitrene undergoes subsequent rearrangements to two isomeric... (Review)
Review
The photolysis of 2-azidofluorene in solid argon at 3 K results in the formation of 2-fluorenylnitrene. The nitrene undergoes subsequent rearrangements to two isomeric didehydroazepines (ketenimines) which differ in the position of the N atom in the seven-membered ring. The rearrangement of the nitrene to the didehydroazepines proceeds in a two-step process. The first step is a photochemical rearrangement to form the corresponding isomeric benzazirines and . The second step is the opening of the three-membered rings of and to form the isomeric didehydroazepines. While benzazirine could easily be detected, isomer was not observed, despite the corresponding didehydroazepine being formed in the matrix. Further experiments revealed that rearranges to the didehydroazepine via heavy-atom tunneling. Semiquantitative estimations based on DFT calculations confirm that should undergo a tunneling rearrangement with tunneling rates on the order of the experimentally observed rates. In contrast, estimations for suggest that for this isomer the tunneling rates should be much larger, resulting in lifetimes too short to be observable under the conditions of matrix isolation. These experiments demonstrate the influence of position isomerism on quantum tunneling rates.
Topics: Isomerism; Imines; Photolysis
PubMed: 37204141
DOI: 10.1021/acs.joc.3c00484 -
Environmental Research Jun 2022(Micro)plastics pollution has raised global concern because of its potential threat to the biota. The review on recent developments of photocatalytic degradation of... (Review)
Review
(Micro)plastics pollution has raised global concern because of its potential threat to the biota. The review on recent developments of photocatalytic degradation of (micro)plastics is still insufficient. In this study, we have discussed various bare and composites photocatalysts involved in the photocatalytic degradation of (micro)plastics. The photocatalytic mechanisms and factors affecting the degradation were also discussed. To improve the performance of photocatalysts, their surface is modified with metal or non-metal dopants. These doped photocatalysts are then compounded with a variety of environmentally friendly and nontoxic polymers to prepare multifunctional composites. The generation of reactive oxygen species (ROS) plays an important role in the photocatalytic degradation of (micro)plastics, and superoxide ions (O) and hydroxyl radicals (OH) participate in the photocatalytic degradation, leading to the breaking of the polymer chain and the production of some intermediates. Although satisfactory progress has been achieved in the photodegradation of (micro)plastics, most photocatalytic degradation technologies investigated to date cannot realize the complete mineralization of (micro)plastics. Furthermore, based on the current challenges of the existing photocatalytic degradation technologies, perspectives for future research directions have been proposed. This review presents a systematic summary of the progress made in the photocatalytic degradation of (micro)plastics and offers a comprehensive reference for future research on improving the (micro)plastics photocatalytic degradation efficiency.
Topics: Catalysis; Photolysis; Plastics; Titanium
PubMed: 35065068
DOI: 10.1016/j.envres.2022.112729 -
Environmental Science & Technology Dec 2017New insensitive munitions explosives, including 2,4-dinitroanisole (DNAN), are replacing traditional explosive compounds to protect soldiers and simplify transport...
New insensitive munitions explosives, including 2,4-dinitroanisole (DNAN), are replacing traditional explosive compounds to protect soldiers and simplify transport logistics. Despite the occupational safety benefits of these new explosives, feasible strategies for cleaning up DNAN from soil and water have not been developed. Here, we evaluate the metabolism of DNAN by the model plant Arabidopsis to determine whether phytoremediation can be used to clean up contaminated sites. Furthermore, we evaluate the role of photodegradation of DNAN and its plant metabolites within Arabidopsis leaves to determine the potential impact of photolysis on the phytoremediation of contaminants. When exposed to DNAN for three days, Arabidopsis took up and metabolized 67% of the DNAN in hydroponic solution. We used high resolution and tandem mass spectrometry in combination with stable-isotope labeled DNAN to confirm ten phase II DNAN metabolites in Arabidopsis. The plants separately reduced both the para- and ortho-nitro groups and produced glycosylated products that accumulated within plant tissues. Both DNAN and a glycosylated metabolite were subsequently photolyzed within leaf tissue under simulated sunlight, and [N]DNAN yielded NO in leaves. Therefore, photolysis inside leaves may be an important, yet under-explored, phytoremediation mechanism.
Topics: Anisoles; Arabidopsis; Explosive Agents; Photolysis
PubMed: 29131608
DOI: 10.1021/acs.est.7b04220 -
Chemosphere Jun 2023Polybrominated diphenyl ethers (PBDEs) are halogenated organic compounds that are among the major pollutants of water, and there is an urgent need for their removal....
Comparison of photocatalysis and photolysis of 2,2,4,4-tetrabromodiphenyl ether (BDE-47): Operational parameters, kinetic studies, and data validation using three modern machine learning models.
Polybrominated diphenyl ethers (PBDEs) are halogenated organic compounds that are among the major pollutants of water, and there is an urgent need for their removal. This work compared the application of two techniques, i.e., photocatalytic reaction (PCR) and photolysis (PL), for 2,2,4,4- tetrabromodiphenyl ether (BDE-47) degradation. Although a limited degradation of BDE-47 was observed by photolysis (LED/N), photocatalytic oxidation by using TiO/LED/N proved to be effective in the degradation of BDE-47. The use of a photocatalyst enhanced the extent of BDE-47 degradation by around 10% at optimum conditions in anaerobic systems. Experimental results were systematically validated through modeling with three new and powerful Machine Learning (ML) approaches, including Gradient Boosted Decision Tree (GBDT), Artificial Neural Network (ANN), and Symbolic Regression (SBR). Four statistical criteria (Coefficient of Determination (R), Root Mean Square Error (RMSE), Average Relative Error (ARER), and Absolute Error (ABER)) were calculated for model validation. Among the applied models, the developed GBDT was the desirable model for predicting the remaining concentration (Ce) of BDE-47 for both processes. Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) results confirmed that BDE-47 mineralization required additional time than its degradation in both PCR and PL systems. The kinetic study demonstrated that BDE-47 degradation for both processes followed the pseudo-first-order form of the Langmuir-Hinshelwood (L-H) model. More importantly, the calculated electrical energy consumption of photolysis was shown to be ten percent higher than that for photocatalysis, possibly due to the higher irradiation time required in direct photolysis, which in turn increases electricity consumption. This study is useful in proposing a feasible and promising treatment process for the degradation of BDE-47.
Topics: Halogenated Diphenyl Ethers; Kinetics; Ether; Photolysis; Ethyl Ethers
PubMed: 36907486
DOI: 10.1016/j.chemosphere.2023.138363 -
Environmental Science & Technology Sep 2018Photochemical reactions contribute to the transformation of contaminants and biogeochemically important substrates in environmental aquatic systems. Recent research has... (Review)
Review
Photochemical reactions contribute to the transformation of contaminants and biogeochemically important substrates in environmental aquatic systems. Recent research has demonstrated that halogen radicals (e.g., Cl, Br, Cl, BrCl, Br) impact photochemical processes in sunlit estuarine and coastal waters rich in halides (e.g., chloride, Cl, and bromide, Br). In addition, halogen radicals participate in contaminant degradation in some engineered processes, including chlorine photolysis for drinking water treatment and several radical-based processes for brine and wastewater treatment. Halogen radicals react selectively with substrates (with bimolecular rate constants spanning several orders of magnitude) and via several potential chemical mechanisms. Consequently, their role in photochemical processes remains challenging to assess. This review presents an integrative analysis of the chemistry of halogen radicals and their contribution to aquatic photochemistry in sunlit surface waters and engineered treatment systems. We evaluate existing data on the generation, speciation, and reactivity of halogen radicals, as well as experimental and computational approaches used to obtain this data. By evaluating existing data and identifying major uncertainties, this review provides a basis to assess the impact of halogen radicals on photochemical processes in both saline surface waters and engineered treatment systems.
Topics: Bromides; Halogens; Oxidants; Photolysis; Water Pollutants, Chemical; Water Purification
PubMed: 30080407
DOI: 10.1021/acs.est.8b02219 -
Environmental Science and Pollution... Jan 2022The disposal of dye-contaminated wastewater is a major concern around the world for which a variety of techniques are used for its treatment. The photocatalytic... (Review)
Review
The disposal of dye-contaminated wastewater is a major concern around the world for which a variety of techniques are used for its treatment. The photocatalytic treatment of dye-contaminated wastewater is one of the treatment methods. Semiconductor-assisted photocatalytic treatment of dye-contaminated wastewater has gained pronounced attention recently. This review outlines the recent advancements in the photocatalytic treatment of dye-contaminated wastewater. The photocatalytic degradation of dyes follows three types of mechanisms: (1) dye sensitization through charge injection, (2) indirect dye degradation through oxidation/reduction, and (3) direct photolysis of dye. Several experimental parameters like initial concentration of dyes, pH, and catalyst dosage significantly affect the photocatalytic degradation of dyes. The photocatalytic materials can be categorized into three generations. The single-component (e.g., ZnO, TiO) and multiple component semiconductor metal oxides (e.g., ZnO-TiO, BiO-ZnO) are categorized as first-generation and second-generation photocatalysts, respectively. The photocatalysts dispersed on an inert solid substrate (e.g., Ag-AlO, ZnO-C) are classified as third-generation photocatalysts. Finally, we reviewed the challenges that affect the photocatalytic degradation of dyes.
Topics: Catalysis; Coloring Agents; Photolysis; Semiconductors; Wastewater
PubMed: 34523090
DOI: 10.1007/s11356-021-16389-7 -
Angewandte Chemie (International Ed. in... Oct 2023Cellular membranes, including the plasma and endosome membranes, are barriers to outside proteins. Various vehicles have been devised to deliver proteins across the...
Cellular membranes, including the plasma and endosome membranes, are barriers to outside proteins. Various vehicles have been devised to deliver proteins across the plasma membrane, but in many cases, the payload gets trapped in the endosome. Here we designed a photo-responsive phase-separating fluorescent molecule (PPFM) with a molecular weight of 666.8 daltons. The PPFM compound condensates as fluorescent droplets in the aqueous solution by liquid-liquid phase separation (LLPS), which disintegrate upon photoirradiation with a 405 nm light-emitting diode (LED) lamp within 20 min or a 405 nm laser within 3 min. The PPFM coacervates recruit a wide range of peptides and proteins and deliver them into mammalian cells. Photolysis disperses the payload from condensates into the cytosolic space. Altogether, a type of small molecules that are photo-responsive and phase separating are discovered; their coacervates can serve as transmembrane vehicles for intracellular delivery of proteins, whereas photo illumination triggers the cytosolic distribution of the payload.
Topics: Cell Membrane; Peptides; Photolysis; Light
PubMed: 37648812
DOI: 10.1002/anie.202307045 -
Water Research May 2020For decades, photolysis and photocatalysis have been touted as promising environment-benign and robust technologies to degrade refractory pollutants from water. However,... (Review)
Review
For decades, photolysis and photocatalysis have been touted as promising environment-benign and robust technologies to degrade refractory pollutants from water. However, extensive, large-scale engineering applications remain limited now. To facilitate the technology transfer process, earlier reviews have advocated to developing more cost-effective and innocuous materials, maximizing efficiency of photon usage, and optimizing photoreactor systems, mostly from material and reactor improvement perspectives. However, there are also some fundamental yet critical chemistry issues in photo(cata)lysis processes demanding more in-depth understanding and more careful consideration. Hence, this review summarizes some of these challenges. Of them, the first and paramount issue is the interference of coexisting compounds, including dissolved organic matter, anions, cations, and spiked additives. Secondly, considerable concerns are pointed to the formation of undesirable reaction by-products, such as halogenated, nitrogenous, and sulfur-containing compounds, which might increase instead of reduce toxicity of water if inadequate fluence and catalyst/additive are supplied due to time and cost constraints. Lastly, a critical issue lies in the uncertainty of current approaches used for identifying and quantifying radicals, especially when multiple radicals coexist together under changing and interconvertible conditions. The review hence highlights the needs to better understand these fundamental chemistry issues and meanwhile calls for more delicate design of experiments in future studies to overcome these barriers.
Topics: Environmental Pollutants; Photolysis; Water; Water Pollutants, Chemical; Water Purification
PubMed: 32078833
DOI: 10.1016/j.watres.2020.115605 -
Biochimica Et Biophysica Acta. Proteins... Jul 2018Living organisms on the Earth almost exclusively use l-amino acids for the molecular architecture of proteins. The biological occurrence of d-amino acids is rare,... (Review)
Review
Living organisms on the Earth almost exclusively use l-amino acids for the molecular architecture of proteins. The biological occurrence of d-amino acids is rare, although their functions in various organisms are being gradually understood. A possible explanation for the origin of biomolecular homochirality is the delivery of enantioenriched molecules via extraterrestrial bodies, such as asteroids and comets on early Earth. For the asymmetric formation of amino acids and their precursor molecules in interstellar environments, the interaction with circularly polarized photons is considered to have played a potential role in causing chiral asymmetry. In this review, we summarize recent progress in the investigation of chirality transfer from chiral photons to amino acids involving the two major processes of asymmetric photolysis and asymmetric synthesis. We will discuss analytical data on cometary and meteoritic amino acids and their potential impact delivery to the early Earth. The ongoing and future ambitious space missions, Hayabusa2, OSIRIS-REx, ExoMars 2020, and MMX, are scheduled to provide new insights into the chirality of extraterrestrial organic molecules and their potential relation to the terrestrial homochirality. This article is part of a Special Issue entitled: d-Amino acids: biology in the mirror, edited by Dr. Loredano Pollegioni, Dr. Jean-Pierre Mothet and Dr. Molla Gianluca.
Topics: Amino Acids; Evolution, Molecular; Extraterrestrial Environment; Light; Photolysis; Stereoisomerism
PubMed: 29357311
DOI: 10.1016/j.bbapap.2018.01.004