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Environmental Science and Pollution... May 2022The inactivation processes of coliform bacteria (total and fecal) and sulphito-reducing Clostridium bacteria (vegetative species and spores) in water maturation lagoon...
The inactivation processes of coliform bacteria (total and fecal) and sulphito-reducing Clostridium bacteria (vegetative species and spores) in water maturation lagoon of a low-cost nature-based wastewater treatment plant using constructed wetlands and through processes of photolysis in a pilot photoreactor have been comparatively studied. The different inactivation mechanisms by photolysis of these bacteria have been studied following the criteria of different statistical and kinetic models. Clostridium disinfection treatments fit models in which two types of bacteria populations coexist, one sensitive (vegetative species) and the other (spores) resistant to the treatment, the sensitive one (94%) with an inactivation rate of k = 0.24 ± 0.07 min and the resistant one (6%) with k = 0.11 ± 0.05 min. Total coliform photolytic disinfection also shows two populations with different physiological state. The time required to reduce the first logarithmic decimal cycle of the different types of bacteria (physiological states) are δ = 4.2 ± 0.9 and δ = 8.3 ± 1.1 min, respectively. For fecal coliform photolytic disinfection, only bacteria population, with k = 1.15 ± 0.19 min, is found. The results obtained confirm the photolytic disinfection processes and maturation lagoon are effective systems for Clostridia bacteria removal after water treatment by nature-based systems. Total removal of coliform bacteria is not achieved by maturation lagoons, but their reduction is significant using low doses of cumulative radiation.
Topics: Bacteria; Clostridium; Disinfection; Photolysis; Ultraviolet Rays; Wastewater; Water Purification
PubMed: 35060052
DOI: 10.1007/s11356-021-18184-w -
European Review For Medical and... Oct 2021Spray formulations are currently under development in the field of topical photoprotection. Such forms are characterized by their high fluidity, a property that is...
OBJECTIVE
Spray formulations are currently under development in the field of topical photoprotection. Such forms are characterized by their high fluidity, a property that is obtained by the presence of alcohol in the formula. The purpose of this work was to study the influence of ethanol in sunscreens on the photoprotective efficacy as well as the photostability of UV filters.
MATERIALS AND METHODS
The filters tested were octyl methoxycinnamate (OMC), PEG-25 PABA, octyl salicylate and butyl methoxydibenzoylmethane (BMDBM) at their maximum concentration authorized by European regulations and in the presence of increasing amounts of alcohol, up to 15% (w/w).
RESULTS
The effect of the presence of alcohol on the efficacy of the filters and their photostability varies depending on the molecule considered. Alcohol has no effect on octyl salicylate, either on its efficacy or its photostability. However, filter stabilization is seen for BMDBM and PEG-25 PABA.
CONCLUSIONS
Although these differences are significant, they are not great enough to justify large-scale use of ethanol in sunscreen products due to some of its properties, such as flammability.
Topics: 4-Aminobenzoic Acid; Cinnamates; Drug Compounding; Drug Stability; Ethanol; Photolysis; Polyethylene Glycols; Propiophenones; Salicylates; Sunscreening Agents
PubMed: 34661262
DOI: 10.26355/eurrev_202110_26880 -
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 -
Environmental Science & Technology Oct 2018Growing demands and increasing scarcity of fresh water resources necessitate potable water reuse, which has been implemented with the aid of UV-based advanced oxidation...
Growing demands and increasing scarcity of fresh water resources necessitate potable water reuse, which has been implemented with the aid of UV-based advanced oxidation processes (UV/AOPs) that remove potentially hazardous trace organic contaminants from reclaimed water. During the potable reuse treatment process, chloramines are added to prevent membrane fouling that are carried over to the UV/AOP, where hydrogen peroxide (HO) is commonly added. However, the impact of chloramines on the photolysis of HO and the overall performance of the UV/AOP remains unknown. This study investigated the impacts of the photochemistry of monochloramine (NHCl) and dichloramine (NHCl) associated with the photolysis of HO on the degradation of 1,4-dioxane (1,4-D), a trace organic contaminant ubiquitous in recycled water. Results indicated that NHCl and NHCl alone functioned as oxidants upon UV photolysis, which produced HO and Cl as the two primary oxidative radicals. The speciation of chloramines did not have a significant impact on the degradation kinetics. The inclusion of monochloramine in UV/HO greatly decreased 1,4-D removal efficiency. HO was the major radical in the mixed HO/chloramine system. Results from this study suggest that recognizing the existence of chloramines in UV/HO systems is important for predicting UV/AOP performance in the treatment train of potable reuse.
Topics: Dioxanes; Hydrogen Peroxide; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water; Water Pollutants, Chemical; Water Purification
PubMed: 29791794
DOI: 10.1021/acs.est.8b01023 -
Chemistry (Weinheim An Der Bergstrasse,... May 2023Unconjugated pterins are ubiquitous molecules that participate in countless enzymatic processes and are potentially involved in the photosensitization of singlet oxygen,...
Unconjugated pterins are ubiquitous molecules that participate in countless enzymatic processes and are potentially involved in the photosensitization of singlet oxygen, amino acids, and nucleotides. Following electronic excitation with UV-A light, some of these pterins degrade, producing hydrogen peroxide as the main side product. This process, which is known to take place in vivo, contributes to oxidative stress and melanocyte destruction in vitiligo. In this work, we present for the first time mechanistic insight into the formation of transient triplet species that simultaneously trigger Type I and Type II photosensitizing processes and the initiation of degradation processes. Our calculations reveal that photodegradation of 6-biopterin, which accumulates in the skin of vitiligo patients, leads to 6-formylpterin through a retro-aldol reaction, and subsequently to 6-carboxypterin through a water-mediated aldehyde oxidation. Additionally, we show that the changes in the photosensitizing potential of these systems with pH come from the modulation of their excited-state redox potentials.
Topics: Humans; Vitiligo; Photolysis; Photosensitizing Agents; Pterins; Oxidation-Reduction
PubMed: 36929221
DOI: 10.1002/chem.202300519 -
Nature Methods May 2019We report the identification of a photocleavable anionic surfactant, 4-hexylphenylazosulfonate (Azo), which can be rapidly degraded by ultraviolet irradiation, for...
We report the identification of a photocleavable anionic surfactant, 4-hexylphenylazosulfonate (Azo), which can be rapidly degraded by ultraviolet irradiation, for top-down proteomics. Azo can effectively solubilize proteins with performance comparable to that of sodium dodecyl sulfate (SDS) and is compatible with mass spectrometry. Azo-aided top-down proteomics enables the solubilization of membrane proteins for comprehensive characterization of post-translational modifications. Moreover, Azo is simple to synthesize and can be used as a general SDS replacement in SDS-polyacrylamide gel electrophoresis.
Topics: Azo Compounds; Electrophoresis, Polyacrylamide Gel; Hydrophobic and Hydrophilic Interactions; Mass Spectrometry; Membrane Proteins; Photolysis; Proteomics; Sodium Dodecyl Sulfate; Solubility; Surface-Active Agents; Ultraviolet Rays
PubMed: 30988469
DOI: 10.1038/s41592-019-0391-1 -
International Journal of Molecular... Apr 2022The effect of sodium thiosulfate (ST) on the photodegradation of azathioprine (AZA) was analyzed by UV-VIS spectroscopy, photoluminescence (PL), FTIR spectroscopy, Raman...
The effect of sodium thiosulfate (ST) on the photodegradation of azathioprine (AZA) was analyzed by UV-VIS spectroscopy, photoluminescence (PL), FTIR spectroscopy, Raman scattering, X-ray photoelectron (XPS) spectroscopy, thermogravimetry (TG) and mass spectrometry (MS). The PL studies highlighted that as the ST concentration increased from 25 wt.% to 75 wt.% in the AZA:ST mixture, the emission band of AZA gradual downshifted to 553, 542 and 530 nm. The photodegradation process of AZA:ST induced: (i) the emergence of a new band in the 320-400 nm range in the UV-VIS spectra of AZA and (ii) a change in the intensity ratio of the photoluminescence excitation (PLE) bands in the 280-335 and 335-430 nm spectral ranges. These changes suggest the emergence of new compounds during the photo-oxidation reaction of AZA with ST. The invoked photodegradation compounds were confirmed by studies of the Raman scattering, the FTIR spectroscopy and XPS spectroscopy through: (i) the downshift of the IR band of AZA from 1336 cm to 1331 cm, attributed to N-C-N deformation in the purine ring; (ii) the change in the intensity ratio of the Raman lines peaking at 1305 cm and 1330 cm from 3.45 to 4.57, as the weight of ST in the AZA:ST mixture mass increased; and (iii) the emergence of a new band in the XPS O1s spectrum peaking at 531 eV, which was associated with the C=O bond. Through correlated studies of TG-MS, the main key fragments of ST-reacted AZA are reported.
Topics: Azathioprine; Photolysis; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Thiosulfates
PubMed: 35409337
DOI: 10.3390/ijms23073975 -
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 -
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