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Science Advances Aug 2021The centrality of the Krebs cycle in metabolism has long been interpreted as evidence of its antiquity, and consequently, questions regarding its provenance, and whether...
The centrality of the Krebs cycle in metabolism has long been interpreted as evidence of its antiquity, and consequently, questions regarding its provenance, and whether it initially functioned as a cycle or not, have received much attention. The present report shows that prebiotic oxidation of α-hydroxy carboxylates can be achieved by UV photolysis of a simple geochemical species (HS), which leads to α-oxo carboxylates that feature in the Krebs cycle and glyoxylate shunt. Further reaction of these products leads to almost all intermediates of the Krebs cycle proper, succinate semialdehyde bypass, and glyoxylate shunt. Fumarate, the missing Krebs cycle component, and the required α-hydroxy carboxylates can be provided by a highly related hydrogen cyanide chemistry, which also provides precursors for amino acids, nucleotides, and phospholipids.
PubMed: 34389542
DOI: 10.1126/sciadv.abh3981 -
The Science of the Total Environment Apr 2023Disinfection commonly follows conventional treatments in wastewater treatment and remediation plants aiming at reducing the presence of pathogens. However, the presence...
Disinfection commonly follows conventional treatments in wastewater treatment and remediation plants aiming at reducing the presence of pathogens. However, the presence of the so called "micropollutants" has emerged as a serious concern, therefore developing tertiary treatments that are not only able to remove pathogens but also to degrade micropollutants is worth investigating. Nowadays, UV-C photo-degradation processes are widely used for disinfection due to their simplicity and easy operation; additionally, they have shown potential for the removal of contaminants of emerging concern. Conventional mercury lamps are being replaced by light-emitting diodes (LEDs) that avoid the use of toxic mercury and can be switched on and off with no effect on the lamp lifetime. This work aims to comparatively evaluate the performance of several photo-degradation technologies for the removal of two targeted micropollutants, the pharmaceutical dexamethasone (DXMT) and the herbicide S-metolachlor (MTLC), using UV irradiation doses typical of disinfection processes. To this end, the technical performance of UV-A/UV-C photolysis, UV-A/UV-C photocatalysis, UV-C/HO and UV-C/NaOCl has been compared. The influence of operating conditions such as the initial concentration of the pollutants (3 mg L - 30 mg L, concentrations found in membrane or adsorption remediation steps), pH (3-10), and water matrix (WWTP secondary effluent, and ultrapure water) on the degradation efficiency has been studied. The economic evaluation in terms of electricity and chemicals consumption and the carbon footprint has been evaluated. UV-C photolysis and UV-C photocatalysis appear as the most suitable technologies for the degradation of DXMT and MTLC, respectively, in terms of kinetics (1.53·10 min for DXMT and 1.96·10 min for MTLC), economic evaluation (1 € m for DXMT and 32 € m for MTLC) and environmental indicators (0.5 g-CO for DXMT and 223.1 g-CO for MTLC).
PubMed: 36621496
DOI: 10.1016/j.scitotenv.2022.161376 -
Ecotoxicology and Environmental Safety Sep 2023Pyriclobenzuron (PBU) is a novel molluscicide developed to control Pomacea canaliculate, and little information on its environmental fate has been published. In this...
Pyriclobenzuron (PBU) is a novel molluscicide developed to control Pomacea canaliculate, and little information on its environmental fate has been published. In this study, the photolysis of PBU in an aqueous environment was simulated using a xenon lamp. Results showed that the photolysis of PBU in water followed first-order kinetics, exhibiting a t of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products (PPs) were detected by HPLC-UV and identified by UPLC-Q/TOF MS, which were formed via the hydroxylation and photocatalytic hydro-dehalogenation of PBU, respectively. The initial relative abundance of photolysis product 1 (PP-1) in Milli-Q water was 1.55 times higher than that in river water. PP-1 was detected at 26.5 % and 76.8 % of the maximum relative abundance in the river water and Milli-Q water after 720 h, respectively. Photolysis product 2 (PP-2) was stable in water because of its weak hydrophilicity. The PP-2 detected after 720 h in Milli-Q water and river water was 93.7 % and 93.5 % of the maximum relative abundance, respectively. Finally, ECOSAR software was used to evaluate the acute aquatic toxicity of PBU and its PPs, revealing that the PPs had lower toxicity levels to non-target aquatic organisms.
Topics: Sunlight; Kinetics; Water; Photolysis; Water Pollutants, Chemical
PubMed: 37473704
DOI: 10.1016/j.ecoenv.2023.115272 -
Environmental Science & Technology Jun 2024Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study...
Promotive Effects of Chloride and Sulfate on the Near-Complete Destruction of Perfluorocarboxylates (PFCAs) in Brine via Hydrogen-tuned 185-nm UV Photolysis: Mechanisms and Kinetics.
Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study discovered the promotive effects of two major brine anions, i.e., chloride and sulfate in VUV/H photolysis on the hydrated electron (e) generation and perfluorocarboxylates (PFCAs) destruction and established a kinetics model to elucidate the promotive effects on the steady-state concentration of e ([e]). Results showed that VUV/H achieved near-complete defluorination of perfluorooctanoic acid (PFOA) in the presence of up to 1000 mM chloride or sulfate at pH 12. The defluorination rate constant () of PFOA peaked with a chloride concentration at 100 mM and with a sulfate concentration at 500 mM. The promotive effects of chloride and sulfate were attributed to an enhanced generation of e via their direct VUV photolysis and conversion of additionally generated hydroxyl radical to e by H, which was supported by a linear correlation between the predicted [e] and experimentally observed . The value increased from pH 9 to 12, which was attributed to the speciation of the H/e pair. Furthermore, the VUV system achieved >95% defluorination and ≥99% parent compound degradation of a concentrated PFCAs mixture in a synthetic brine, without generating any toxic perchlorate or chlorate.
Topics: Kinetics; Photolysis; Ultraviolet Rays; Fluorocarbons; Sulfates; Hydrogen; Chlorides; Salts; Water Pollutants, Chemical; Caprylates
PubMed: 38808621
DOI: 10.1021/acs.est.3c10552 -
Environment International Jul 2023The photochemical behaviors of chiral pollutants in aqueous solutions are rarely studied using chiral monomers, which may hamper their precise risk assessment and lead...
The photochemical behaviors of chiral pollutants in aqueous solutions are rarely studied using chiral monomers, which may hamper their precise risk assessment and lead to suspicious conclusions. In this study, we systematically investigated the phototransformation behavior and toxicity evolution of two widely used chiral pesticides (triadimefon (TF) and triadimenol (TN)) at enantiomer and diastereomer levels, and proposed a calculation method of total photolysis rate constants of chiral mixture. Results show that TF and TN could be photodegraded faster in pure water than in natural waters, and the observed photolysis rate constants (k) of TN with two chiral centers exhibit enantioselectivity, i.e., k(TN-RS) = k(TN-SR) > k(TN-RR) = k(TN-SS). The photolysis of TF and TN mainly occurs through their excited singlet and triplet states, respectively. Their photodegradation pathways mainly include dechlorination and elimination of triazole ring. TF could also undergo ether bond cleavage. It is also found that, both TF and TN exhibit photo-induced toxicity to V. fischeri, due to the generation of more toxic products than parent compounds. Furthermore, TN exhibits enantioselective photo-induced toxicity after 240-min irradiation, which could be ascribed to the formation of chiral products. These results could benefit the understanding of enantioselective environmental behavior of chiral pollutants.
Topics: Pesticides; Environmental Pollutants; Photolysis; Stereoisomerism; Water; Water Pollutants, Chemical; Kinetics
PubMed: 37276764
DOI: 10.1016/j.envint.2023.107996 -
Nature Communications Dec 2023Prodrug photolysis enables spatiotemporal control of drug release at the desired lesions. For photoactivated therapy, near-infrared (NIR) light is preferable due to its...
Prodrug photolysis enables spatiotemporal control of drug release at the desired lesions. For photoactivated therapy, near-infrared (NIR) light is preferable due to its deep tissue penetration and low phototoxicity. However, most of the photocleavable groups cannot be directly activated by NIR light. Here, we report a upconversion-like process via only one step of energy transfer for NIR light-triggered prodrug photolysis. We utilize a photosensitizer (PS) that can be activated via singlet-triplet (S-T) absorption and achieve photolysis of boron-dipyrromethene (BODIPY)-based prodrugs via triplet-triplet energy transfer. Using the strategy, NIR light can achieve green light-responsive photolysis with a single-photon process. A wide range of drugs and bioactive molecules are designed and demonstrated to be released under low-irradiance NIR light (100 mW/cm, 5 min) with high yields (up to 87%). Moreover, a micellar nanosystem encapsulating both PS and prodrug is developed to demonstrate the practicality of our strategy in normoxia aqueous environment for cancer therapy. This study may advance the development of photocleavable prodrugs and photoresponsive drug delivery systems for photo-activated therapy.
Topics: Prodrugs; Photolysis; Drug Delivery Systems; Photosensitizing Agents; Energy Transfer
PubMed: 38062051
DOI: 10.1038/s41467-023-43805-y -
Marine Pollution Bulletin Feb 2023Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation...
Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7-2.3 % yr of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea.
Topics: Plastics; Photolysis; Microplastics; Polymers; Environmental Pollution; Environmental Monitoring; Water Pollutants, Chemical
PubMed: 36640499
DOI: 10.1016/j.marpolbul.2022.114544 -
The Science of the Total Environment Jan 2022The increasing consumption of azole antifungal agents leads to their uncontrolled release into the environment. Therefore, it is crucial to remove their residues from...
The increasing consumption of azole antifungal agents leads to their uncontrolled release into the environment. Therefore, it is crucial to remove their residues from natural ecosystems. This study aimed to examine the biological and chemical degradation of four typical azole fungicides: fluconazole (Fc), clotrimazole (Cl), climbazole (Cb), and epoxiconazole (Ep). The biodegradation was investigated using activated sludge and two novel Gram-negative bacterial strains. The chemical degradation experiments aimed to assess the efficiency of fungicides removal through UV treatment, the Fenton reaction, and a combination of these methods. Transformation products of Cb, Ep, and Cl photocatalytic removal were identified by mass spectrometry. In addition, the AlamarBlue® Assay and the MTT Assay allowed careful evaluation of the toxicity of azole derivatives and their transformation products towards newly isolated strains, Stenotrophomonas maltophilia AsPCl2.3 and Pseudomonas monteilii LB2. Among all azole fungicides, Cb was the most susceptible to biological removal while Fc, Ep, and Cl were basically resistant to biodegradation. Cl and Ep showed a significant biosorption on the activated sludge. Under optimized photolysis conditions, the removal efficiency of Cl, Cb, and Ep was significantly higher than that of biodegradation. The Fenton reaction supported by the UV-irradiation offered the best results of fungicides elimination. After 1 min of the experiment, Cl was almost completely removed while Cb and Ep removal rates reached an average of 60%. The proposed main degradation route of azole fungicides during UV-irradiation includes halogen atoms substitution by hydroxyl moieties. The final degradation product was imidazole or triazole. Azole fungicides and their transformation products differently affected the metabolic activity of Gram-negative bacteria. Cl and Cb intermediates showed lower toxicity than parent compounds. The findings help better understand the environmental impact of azole fungicides, their degradation, and toxicity. They also stress the need for reducing their uncontrolled release to the environment.
Topics: Azoles; Ecosystem; Fungicides, Industrial; Pseudomonas; Water Pollutants, Chemical
PubMed: 34525765
DOI: 10.1016/j.scitotenv.2021.149917 -
Heliyon Jul 2020The purpose of this work was to determine the tautomerism, the conformational analysis and photoreactivity of dehydroacetic acid (DHAA, ). For that reason, the...
The purpose of this work was to determine the tautomerism, the conformational analysis and photoreactivity of dehydroacetic acid (DHAA, ). For that reason, the photolysis of DHAA () was performed at 254 nm and compared with two structurally similar compounds: 2-hydroxyacetophenone (HAP, ) and 2-acetyl-1,3-cyclohexanodione (ACH, ). We confirmed the degradation of to acetic acid and we propose a mechanism on the assumption that a [2+2] cyclodimerization occurs (after UV light absorption) followed by some consecutive Norrish Type I cleavages, affording ketenes that end-up in acetic acid. The UV absorption study was conducted for all three compounds to gain insight about their electronic transitions, both experimentally and with computational simulations using TDDFT (B3LYP/6-31+G(d,p)) methods. A detailed analysis of the different tautomers and isomers that can be present in solution and the MOs involved in the electronic transitions was also achieved. The HOMO→LUMO transition was the least energetic optically active transition for and , whereas was recognized to have a HOMO-1→LUMO transition. These transitions were all of n→π character.
PubMed: 32728640
DOI: 10.1016/j.heliyon.2020.e04457 -
ACS Environmental Au May 2022Fluorine incorporation into organic molecules has increased due to desirable changes in the molecular physiochemical properties. Common fluorine motifs include:...
Tracking Fluorine during Aqueous Photolysis and Advanced UV Treatment of Fluorinated Phenols and Pharmaceuticals Using a Combined F-NMR, Chromatography, and Mass Spectrometry Approach.
Fluorine incorporation into organic molecules has increased due to desirable changes in the molecular physiochemical properties. Common fluorine motifs include: aliphatic fluorines and -CF, or -F containing groups bonded directly onto an aromatic (Ar-CF and Ar-F) or heteroaromatic ring. Photolysis of these compounds, either in natural or engineered systems, is a potential source of new fluorinated byproducts. Given the potential persistence and toxicity of fluorinated byproducts, monitoring of product formation during photolysis of various fluorinated motifs is needed. F-NMR is a means to detect and quantify these species. Ar-CF and Ar-F model compounds (2-, 3-, and 4-(trifluoromethyl)phenol, 2-, 3-, 4-fluorophenol, and 2,6-, 3,5-difluorophenol) were photolyzed under a variety of aqueous conditions: pH 5, pH 7, pH 10, 1 mM HO at pH 7 to form •OH, and 0.5 mM SO at pH 10 to form e . Pharmaceuticals with the Ar-CF (fluoxetine) and Ar-F plus pyrazole-CF (sitagliptin) motifs were treated similarly. Parent molecule concentrations were monitored with high pressure liquid chromatography with a UV detector. Fluorine in the parent and product molecules was quantified with F-NMR and complete fluorine mass balances were obtained. High resolution mass spectrometry was used to further explore product identities. The major product for Ar-F compounds was fluoride. The Ar-CF model compounds led to fluoride and organofluorine products dependent on motif placement and reaction conditions. Trifluoroacetic acid was a product of 4-(trifluoromethyl)phenol and fluoxetine. Additional detected fluoxetine products identified using mass spectrometry resulted from addition of -OH to the aromatic ring, but a dealkylation product could not be distinguished from fluoxetine by F-NMR. Sitagliptin formed multiple products that all retained the pyrazole-CF motif while the Ar-F motif produced fluoride. F-NMR, mass spectrometry, and chromatography methods provide complementary information on the formation of fluorinated molecules by modification or fragmentation of the parent structure during photolysis, allowing screening for fluorinated photoproducts and development of fluorine mass balances.
PubMed: 37102144
DOI: 10.1021/acsenvironau.1c00057