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Water Research Feb 2024The presence of estrogens in water environments has raised concerns for human health and ecosystems balance. These substances possess potent estrogenic properties,...
The presence of estrogens in water environments has raised concerns for human health and ecosystems balance. These substances possess potent estrogenic properties, causing severe disruptions in endocrine systems and leading to reproductive and developmental problems. Unfortunately, conventional treatment methods struggle to effectively remove estrogens and mitigate their effects, necessitating technological innovation. This study investigates the effectiveness of a novel sequential photolysis-granular activated carbon (GAC) sandwich biofiltration (GSBF) system in removing estrogens (E1, E2, E3, and EE2) and improving general water quality parameters. The results indicate that combining photolysis pre-treatment with GSBF consistently achieved satisfactory performance in terms of turbidity, dissolved organic carbon (DOC), UV, and microbial reduction, with over 77.5 %, 80.2 %, 89.7 %, and 92 % reduction, respectively. Furthermore, this approach effectively controlled the growth of microbial biomass under UV irradiation, preventing excessive head loss. To assess estrogen removal, liquid chromatography-tandem mass spectrometry (LC-MS) measured their concentrations, while bioassays determined estrogenicity. The findings demonstrate that GSBF systems, with and without photolysis installation, achieved over 96.2 % removal for estrogens when the spike concentration of each targeted compound was 10 µg L, successfully reducing estrogenicity (EA/EA0) to levels below 0.05. Additionally, the study evaluated the impact of different thicknesses of GAC layer filling (8 cm, 16 cm, and 24 cm) and found no significant difference (p>0.05) in estrogen and estrogenicity removal among them.
Topics: Humans; Estrogens; Photolysis; Ecosystem; Water Pollutants, Chemical; Estrone; Charcoal
PubMed: 38064783
DOI: 10.1016/j.watres.2023.120976 -
The Science of the Total Environment Jun 2020The degradation of enrofloxacin (ENR) by direct photolysis, Fenton and solar photo-Fenton processes has been studied in different water matrices, such as ultra-pure...
The degradation of enrofloxacin (ENR) by direct photolysis, Fenton and solar photo-Fenton processes has been studied in different water matrices, such as ultra-pure water (MQ), tap water (TW) and highly saline water (SW). Reactions have been conducted at initial pH 2.8 and 5.0. At pH = 2.8, HPLC analyses showed a fast removal of ENR by (solar photo)-Fenton treatments in all studied water matrices, whereas a 40% removal was observed after 120 min of photolysis. However, TOC measurements showed that only solar photo-Fenton was able to produce significant mineralization (80% after 120 min of treatment); differences between ENR removal and mineralization can be attributed to the release of important amounts of reaction by-products. Excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were employed to gain further insight into the nature of these by-products and their time-course profile, obtaining a 5-component model. EEM-PARAFAC results indicated that photolysis is not able to produce important changes in the fluoroquinolone structure, in sharp contrast with (solar photo)-Fenton, where decrease of the components associated with fluoroquinolone core was observed. Agar diffusion tests employing E. coli and S, aureus showed that the antibiotic activity decreased in parallel with the destruction of the fluoroquinolone core.
Topics: Biological Assay; Enrofloxacin; Escherichia coli; Factor Analysis, Statistical; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Oxidation-Reduction; Photolysis; Water; Water Pollutants, Chemical
PubMed: 32112955
DOI: 10.1016/j.scitotenv.2020.137331 -
Organic Letters May 2019In an ongoing effort to study the environmental fate of endocrine-active steroid hormones, we report the formation of phenolic rearrangement products (3 and 4) with a...
In an ongoing effort to study the environmental fate of endocrine-active steroid hormones, we report the formation of phenolic rearrangement products (3 and 4) with a novel 6,5,8,5-ring system following aqueous photolysis of dienogest (1) and methyldienolone (2). The structures were established by analysis of 2D NMR and HRMS data, and that of 3 was confirmed by X-ray diffraction analysis. These photoproducts exhibit progestogenic and androgenic activity, albeit with less potency than their parent compounds.
Topics: Molecular Structure; Nandrolone; Pharmaceutical Preparations; Photolysis; Steroids
PubMed: 31021644
DOI: 10.1021/acs.orglett.9b00972 -
Environmental Science & Technology May 2023Singlet oxygen (O) is an important reactive species in natural waters produced during photolysis of dissolved organic matter (DOM). Prior studies have demonstrated that...
Singlet oxygen (O) is an important reactive species in natural waters produced during photolysis of dissolved organic matter (DOM). Prior studies have demonstrated that O exhibits a microheterogeneous distribution, with [O] in the interior of DOM macromolecules ∼30 to 1000-fold greater than in bulk solution. The [O] profile for DOM-containing solutions has been determined mainly by the use of hydrophobic probes, which are not commercially available. In this study, we employed a dual-probe method combining the widely used hydrophilic O probe furfuryl alcohol (FFA) and its structural analogue furfuryl amine (FFAm). FFAm exists mainly as a cation at pH <9 and was therefore hypothesized to have an enhanced local concentration in the near-DOM phase, whereas FFA will be distributed homogeneously. The probe pair was used to quantify apparent [O] in DOM samples from different isolation procedures (humic acid, fulvic acid, reverse osmosis) and diverse origins (aquatic and terrestrial) as a function of pH and ionic strength, and all samples studied exhibited enhanced reactivity of FFAm relative to FFA, especially at pH 7 and 8. To quantify the spatial distribution of [O], we combined electrostatic models with Latch and McNeill's three-phase distribution model. Modeling results for Suwannee River humic acid (SRHA) yield a surface [O] of ∼60 pM, which is ∼96-fold higher than the aqueous-phase [O] measured with FFA. This value is in agreement with prior reports that determined 1-3 orders of magnitude higher [O] in the DOM phase compared to bulk solution. Overall, this work expands the knowledge base of DOM microheterogeneous photochemistry by showing that diverse DOM isolates exhibit this phenomenon. In addition, the dual-probe approach and electrostatic modeling offer a new way to gain mechanistic insight into the spatial distribution of O and potentially other photochemically produced reactive intermediates.
Topics: Singlet Oxygen; Amines; Humic Substances; Water; Photolysis; Dissolved Organic Matter
PubMed: 37130219
DOI: 10.1021/acs.est.3c01726 -
Journal of Hazardous Materials Jun 2023Increasing drug residues in aquatic environments have been caused by the abuse of antivirals since the global spread of the COVID-19 epidemic, whereas research on the...
Increasing drug residues in aquatic environments have been caused by the abuse of antivirals since the global spread of the COVID-19 epidemic, whereas research on the photolytic mechanism, pathways and toxicity of these drugs is limited. The concentration of COVID-19 antivirals ribavirin in rivers has been reported to increase after the epidemic. Its photolytic behavior and environmental risk in actual waters such as wastewater treatment plant (WWTP) effluent, river water and lake water were first investigated in this study. Direct photolysis of ribavirin in these media was limited, but indirect photolysis was promoted in WWTP effluent and lake water by dissolved organic matter and NO. Identification of photolytic intermediates suggested that ribavirin was photolyzed mainly via C-N bond cleavage, splitting of the furan ring and oxidation of the hydroxyl group. Notably, the acute toxicity was increased after ribavirin photolysis owing to the higher toxicity of most of the products. Additionally, the overall toxicity was greater when ARB photolysis in WWTP effluent and lake water. These findings emphasize the necessity to concern about the toxicity of ribavirin transformation in natural waters, as well as to limit its usage and discharge.
Topics: Humans; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Antiviral Agents; COVID-19; Photolysis; Ribavirin; Water; Water Pollutants, Chemical
PubMed: 37002997
DOI: 10.1016/j.jhazmat.2023.131320 -
Molecules (Basel, Switzerland) May 2022The development of multifunctional nanomaterials has received growing research interest, thanks to its ability to combine multiple properties for severing highly...
The development of multifunctional nanomaterials has received growing research interest, thanks to its ability to combine multiple properties for severing highly demanding purposes. In this work, holmium oxide nanoparticles are synthesized and characterized by various tools including XRD, XPS, and TEM. These nanoparticles are found to emit near-infrared fluorescence (800-1100 nm) under a 785 nm excitation source. Imaging of the animal tissues was demonstrated, and the maximum imaging depth was found to be 2.2 cm. The synthesized nanoparticles also show the capability of facilitating dye (fluorescein sodium salt and rhodamine 6G) degradation under white light irradiation. The synthesized holmium oxide nanoparticles are envisioned to be useful for near-infrared tissue imaging and dye-degradation.
Topics: Animals; Holmium; Light; Nanoparticles; Oxides; Photolysis
PubMed: 35684461
DOI: 10.3390/molecules27113522 -
The Journal of Organic Chemistry Mar 2020Despite its importance in the design of photocaged molecules, less attention is focused on linker chemistry than the cage itself. Here, we describe unique uncaging...
Despite its importance in the design of photocaged molecules, less attention is focused on linker chemistry than the cage itself. Here, we describe unique uncaging properties displayed by two coumarin-caged thymidine compounds, each conjugated with () or without () an extended, self-immolative spacer. Photolysis of using long-wavelength UVA (365 nm) or visible (420, 455 nm) light led to the release of free thymidine along with the competitive generation of a thymidine-bearing recombination product. The occurrence of this undesired side reaction, which is previously unreported, was not present with the photolysis of , which released thymidine exclusively with higher quantum efficiency. We propose that the spatial separation between the cage and the substrate molecule conferred by the extended linker can play a critical role in circumventing this unproductive reaction. This report reinforces the importance of linker selection in the design of coumarin-caged oligonucleosides and other conjugates.
Topics: Coumarins; Photolysis; Thymidine
PubMed: 32020803
DOI: 10.1021/acs.joc.9b02617 -
Environmental Science & Technology Jun 2018A sequential combination of membrane treatment and UV-based advanced oxidation processes (UV/AOP) has become the industry standard for potable water reuse. Chloramines...
A sequential combination of membrane treatment and UV-based advanced oxidation processes (UV/AOP) has become the industry standard for potable water reuse. Chloramines are used as membrane antifouling agents and therefore carried over into the UV/AOP. In addition, persulfate (SO) is an emerging oxidant that can be added into a UV/AOP, thus creating radicals generated from both chloramines and persulfate for water treatment. This study investigated the simultaneous photolysis of SO and monochloramine (NHCl) on the removal of 1,4-dioxane (1,4-D) for potable-water reuse. The dual oxidant effects of NHCl and SO on 1,4-D degradation were examined at various levels of oxidant dosage, chloride, and solution pH. Results showed that a NHCl-to-SO molar ratio of 0.1 was optimal, beyond which the scavenging by NHCl of HO, SO, and Cl radicals decreased the 1,4-D degradation rate. At the optimal ratio, the degradation rate of 1,4-D increased linearly with the total oxidant dose up to 6 mM. The combined photolysis of NHCl and SO was sensitive to the solution pH due to a disproportionation of NHCl at pH lower than 6 into less-photoreactive dichloramine (NHCl) and radical scavenging by NH. The presence of chloride transformed HO and SO to Cl that is less-reactive with 1,4-D, while the presence of dissolved O promoted gaseous nitrogen production. Results from this study suggest that the presence of chloramines can be beneficial to persulfate photolysis in the removal of 1,4-D; however, the treatment efficiency depends on a careful control of an optimal NHCl dosage and a minimal chloride residue.
Topics: Chloramines; Dioxanes; Drinking Water; Osmosis; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water Pollutants, Chemical
PubMed: 29653056
DOI: 10.1021/acs.est.7b06042 -
Efficient Photocatalytic Degradation of Tetracycline on the MnFeO/BGA Composite under Visible Light.International Journal of Molecular... May 2023In this work, the MnFeO/BGA (boron-doped graphene aerogel) composite prepared via the solvothermal method is applied as a photocatalyst to the degradation of...
In this work, the MnFeO/BGA (boron-doped graphene aerogel) composite prepared via the solvothermal method is applied as a photocatalyst to the degradation of tetracycline in the presence of peroxymonosulfate. The composite's phase composition, morphology, valence state of elements, defect and pore structure were analyzed by XRD, SEM/TEM, XPS, Raman scattering and N adsorption-desorption isotherms, respectively. Under the radiation of visible light, the experimental parameters, including the ratio of BGA to MnFeO, the dosages of MnFeO/BGA and PMS, and the initial pH and tetracycline concentration were optimized in line with the degradation of tetracycline. Under the optimized conditions, the degradation rate of tetracycline reached 92.15% within 60 min, whereas the degradation rate constant on MnFeO/BGA remained 4.1 × 10 min, which was 1.93 and 1.56 times of those on BGA and MnFeO, respectively. The largely enhanced photocatalytic activity of the MnFeO/BGA composite over MnFeO and BGA could be ascribed to the formation of type I heterojunction on the interfaces of BGA and MnFeO, which leads to the efficient transfer and separation of photogenerated charge carriers. Transient photocurrent response and electrochemical impedance spectroscopy tests offered solid support to this assumption. In line with the active species trapping experiments, SO and O radicals are confirmed to play crucial roles in the rapid and efficient degradation of tetracycline, and accordingly, a photodegradation mechanism for the degradation of tetracycline on MnFeO/BGA is proposed.
Topics: Catalysis; Anti-Bacterial Agents; Tetracycline; Photolysis; Light
PubMed: 37298330
DOI: 10.3390/ijms24119378 -
The Journal of Physical Chemistry... Aug 2022It is well-known that photolysis of pyrimidine nucleobases, such as uracil, in an aqueous environment results in the formation of hydrate as one of the main products....
It is well-known that photolysis of pyrimidine nucleobases, such as uracil, in an aqueous environment results in the formation of hydrate as one of the main products. Although several hypotheses regarding photohydration have been proposed in the past, e.g., the zwitterionic and "hot" ground-state mechanisms, its detailed mechanism remains elusive. Here, theoretical nonadiabatic simulations of the uracil photodynamics reveal the formation of a highly energetic but kinetically stable intermediate that features a half-chair puckered pyrimidine ring and a strongly twisted intracyclic double bond. The existence and the kinetic stability of the intermediate are confirmed by a variety of computational chemistry methods. According to the simulations, the unusual intermediate is mainly formed almost immediately (∼50-200 fs) upon photoabsorption and survives long enough to engage in a hydration reaction with a neighboring water. A plausible mechanism of uracil photohydration is proposed on the basis of the modeling of nucleophilic insertion of water into the twisted double bond of the intermediate.
Topics: Kinetics; Photolysis; Pyrimidines; Uracil; Water
PubMed: 35900137
DOI: 10.1021/acs.jpclett.2c01694