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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 -
Photochemical & Photobiological... Jan 2021A hypothesis is proposed to explain the increased detrimental effect of COVID-19 for Black, Asian and Minority Ethnic (BAME) men and women compared to Caucasian...
A hypothesis is proposed to explain the increased detrimental effect of COVID-19 for Black, Asian and Minority Ethnic (BAME) men and women compared to Caucasian individuals. This is based on the differing photochemistry of phaeomelanin in fair skin and eumelanin in dark/black skin. It is suggested that a range of reactive oxygen species, including, singlet oxygen and the superoxide radical anion, derived via direct photolysis of phaeomelanin, may escape the melanocyte and cause subsequent damage to the SARS-CoV-2 virus. It is further suggested that (large) carbon and sulphur peroxy radicals, from oxygen addition to radicals formed by carbon-sulphur bond cleavage, may assist via damage to the cell membranes. It is also speculated that light absorption by phaeomelanin and the subsequent C-S bond cleavage, leads to release of pre-absorbed reactive oxygen species, such as singlet oxygen and free radicals, which may also contribute to an enhanced protective effect for fair-skinned people.
Topics: COVID-19; Carbon; Ethnicity; Female; Free Radicals; Humans; Light; Male; Melanins; Photochemical Processes; Photolysis; SARS-CoV-2; Singlet Oxygen; Skin; Sulfur; Superoxides
PubMed: 33721239
DOI: 10.1007/s43630-020-00004-8 -
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 -
Chemistry (Weinheim An Der Bergstrasse,... Oct 2022Catch and release DNA decoys (CRDDs) utilize photochemically responsive nucleoside analogues that generate abasic sites upon exposure to light. Herein, we describe the...
Catch and release DNA decoys (CRDDs) utilize photochemically responsive nucleoside analogues that generate abasic sites upon exposure to light. Herein, we describe the synthesis and evaluation of four candidate CRDD monomers containing nucleobases that mimic endogenous pyrimidines: 2-nitroimidazole (2-NI), 2-nitrobenzene (2-NB), 2-nitropyrrole (2-NP) and 3-nitropyrrole (3-NP). Our studies reveal that 2-NI and 2-NP can function as CRDDs, whereas 3-NP and 2-NB undergo decomposition and transformation to a higher-ordered structure upon photolysis, respectively. When incorporated into DNA, 2-NP undergoes rapid photochemical cleavage of the anomeric bond (1.8 min half-life) to yield an abasic site. Finally, we find that all four pyrimidine mimics show significantly greater stability when base-paired against the previously reported 7-nitroindole CRDD monomer. Our work marks the expansion of CRDD technology to both purine and pyrimidine scaffolds.
Topics: Nucleosides; DNA; Pyrimidines; Purines; Technology; Nitrobenzenes; Nitroimidazoles
PubMed: 35849314
DOI: 10.1002/chem.202201355 -
International Journal of Environmental... Nov 2022This study investigated the photolysis and TiO-assisted photosensitized degradation of oxytetracycline (OTC) under visible light, the active reactive oxygen species...
This study investigated the photolysis and TiO-assisted photosensitized degradation of oxytetracycline (OTC) under visible light, the active reactive oxygen species (ROS), and the degradation mechanisms in these two reactions. The results show that the deprotonated OTC could be photolyzed more easily under visible light because of the redshift of its absorption spectrum at high pH values. Due to the TiO-assisted self-photosensitized degradation of OTC, OTC removal in the visible light/TiO system was more efficient with the addition of TiO, as demonstrated when TiO was replaced with insulator SiO. The study's ROS scavenging experiments show that superoxide radical anion (O) ROS was most responsible for the self-sensitized degradation of OTC in both reactions. OTC degradation under the visible light/TiO system was enhanced with increasing TiO load, while the elimination of total organic carbon (TOC) was very limited after 5 h of visible light irradiation. Based on the eight identified transformation products found, five potential reaction mechanisms, including hydroxylation, quinonization, decarbonylation, de-methylation, and dehydration, were proposed for the photolytic and TiO-assisted photosensitized degradation mechanisms of OTC under visible light. This study indicates that OTC can degrade under visible light with or without a semiconductor when conditions are suitable.
Topics: Oxytetracycline; Reactive Oxygen Species; Silicon Dioxide; Titanium; Light; Catalysis
PubMed: 36497621
DOI: 10.3390/ijerph192315550 -
Materials (Basel, Switzerland) Oct 2021Degradation of 17α-ethynylestradiol (EE2) and estrogenicity were examined in a novel oxidative bioreactor (OBR) that combines small bioreactor platform (SBP) capsules...
Degradation of 17α-ethynylestradiol (EE2) and estrogenicity were examined in a novel oxidative bioreactor (OBR) that combines small bioreactor platform (SBP) capsules and UV-LED (ultraviolet light emission diode) simultaneously, using enriched water and secondary effluent. Preliminary experiments examined three UV-LED wavelengths-267, 279, and 286 nm, with (indirect photolysis) and without (direct photolysis) HO. The major degradation wavelength for both direct and indirect photolysis was 279 nm, while the major removal gap for direct vs. indirect degradation was at 267 nm. Reduction of EE2 was observed together with reduction of estrogenicity and mineralization, indicating that the EE2 degradation products are not estrogens. Furthermore, slight mineralization occurred with direct photolysis and more significant mineralization with the indirect process. The physical-biological OBR process showed major improvement over other processes studied here, at a very short hydraulic retention time. The OBR can feasibly replace the advanced oxidation process of UV-LED radiation with catalyst in secondary sedimentation tanks with respect to reduction ratio, and with no residual HO. Further research into this OBR system is warranted, not only for EE2 degradation, but also to determine its capabilities for degrading mixtures of pharmaceuticals and pesticides, both of which have a significant impact on the environment and public health.
PubMed: 34683555
DOI: 10.3390/ma14205960 -
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 -
Molecules (Basel, Switzerland) Dec 2021The explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is of particular interest due to its extreme insensitivity to impact, shock and heat, while providing a good...
The explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is of particular interest due to its extreme insensitivity to impact, shock and heat, while providing a good detonation velocity. To determine its fate under environmental conditions, TATB powder was irradiated with simulated sunlight and, in water, under UV light at 254 nm. The hydrolysis of particles submerged in neutral and alkaline solutions was also examined. We found that, by changing experimental conditions (e.g., light source, and mass and physical state of TATB), the intermediates and final products were slightly different. Mono-benzofurazan was the major transformation product in both irradiation systems. Two minor transformation products, the -nitro form of TATB and 3,5-diamino-2,4,6-trinitrophenol, were detected under solar light, while 1,3,5-triamino-2-nitroso-4,6-dinitrobenzene, 1,3,5-triamino-2,4-dinitrobenzene and mono-benzofuroxan were produced under UV light. The product identified as 3,5-diamino-2,4,6-trinitrophenol was identical to the one formed in the dark under alkaline conditions (pH 13) and in water incubated at either 50 °C or aged at ambient conditions. Interestingly, when only a few milligrams of TATB were irradiated with simulated sunlight, the -isomer and mono-benzofurazan derivative were detected; however, the hydrolysis product 3,5-diamino-2,4,6-trinitrophenol formed only much later in the absence of light. This suggests that the water released from TATB to form mono-benzofurazan was trapped in the interstitial space between the TATB layers and slowly hydrolyzed the relatively stable -nitro intermediate to 3,5-diamino-2,4,6-trinitrophenol. This environmentally relevant discovery provides data on the fate of TATB in surface environments exposed to sunlight, which can transform the insoluble substrate into more soluble and corrosive derivatives, such as 3,5-diamino-2,4,6-trinitrophenol, and that some hydrolytic transformation can continue even without light.
PubMed: 35011446
DOI: 10.3390/molecules27010214 -
Biomolecules Aug 2020Free-radical-mediated processes, such as peroxidation, isomerization and hydrogenation affecting fatty acid integrity and biological functions, have a trans-disciplinary...
Free-radical-mediated processes, such as peroxidation, isomerization and hydrogenation affecting fatty acid integrity and biological functions, have a trans-disciplinary relevance. Cardiolipins (CL, (1,3-diphosphatidyl--glycerol)) and tetra-linoleoyl-CL are complex phospholipids, exclusively present in the Inner Mitochondrial Membrane (IMM) lipids, where they maintain membrane integrity and regulate enzyme functionalities. Peroxidation pathways and fatty acid remodeling are known causes of mitochondrial disfunctions and pathologies, including cancer. Free-radical-mediated isomerization with the change of the cis CL into geometrical trans isomers is an unknown process with possible consequences on the supramolecular membrane lipid organization. Here, the formation of mono-trans CL (MT-CL) and other trans CL isomers (T-CL) is reported using CL from bovine heart mitochondria and thiyl radicals generated by UV-photolysis from 2-mercaptoethanol. Analytical approaches for CL isomer separation and identification via H/C NMR are provided, together with the chemical study of CL derivatization to fatty acid methyl esters (FAME), useful for lipidomics and metabolomics research. Kinetics information of the radical chain isomerization process was obtained using γ-irradiation conditions. The CL isomerization affected the structural organization of membranes, as tested by the reduction in unilamellar liposome diameter, and accompanied the well-known process of oxidative consumption induced by Fenton reagents. These results highlight a potential new molecular modification pathway of mitochondrial lipids with wide applications to membrane functions and biological consequences.
Topics: Animals; Cardiolipins; Cattle; Chromatography, Gas; Isomerism; Kinetics; Lipid Peroxidation; Lipidomics; Mercaptoethanol; Mitochondria, Heart; Mitochondrial Membranes; Photolysis
PubMed: 32824246
DOI: 10.3390/biom10081189 -
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