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Full-Spectrum Photocatalytic Activity of ZnO/CuO/ZnFe2O4 Nanocomposite as a PhotoFenton-Like Catalyst
摘要： Deriving photocatalysts by the calcination of hydrotalcite-like compounds has attracted growing interest for extending their photocatalytic activity to the visible and even near-infrared (NIR) light regions. Herein, we describe the acquisition of a ZnO/CuO/ZnFe2O4 nanocomposite with good photoFenton-like catalytic activity under UV, visible and near-infrared (NIR) light irradiation by optimizing the calcination temperature of the coprecipitation product of Zn2+, Cu2+ and Fe3+. The ZnO/CuO/ZnFe2O4 nanocomposite is composed of symbiotic crystals of ZnO, CuO and ZnFe2O4, which enable the nanocomposite to show absorption in the UV, visible and NIR light regions and to produce a transient photocurrent in the presence of H2O2 under NIR irradiation. The full-spectrum photoFenton-like catalyst shows improved performance for the degradation of methyl orange with an increasing amount of H2O2 and is very stable in the recycling process. We believe that the ZnO/CuO/ZnFe2O4 nanocomposite is a promising full-spectrum photoFenton-like catalyst for the degradation of organic pollutants.
关键词： ZnO/CuO/ZnFe2O4,photodegradation,Full-spectrum,nanocomposite,photoFenton-like catalyst,near-infrared light,photocatalysis
更新于2025-09-10 09:29:36
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Photocatalytic Properties of Nb/MCM-41 Molecular Sieves: Effect of the Synthesis Conditions
摘要： The effect of synthesis conditions and niobium incorporation levels on the photocatalytic properties of Nb/MCM-41 molecular sieves was assessed. Niobium pentoxide supported on MCM-41 mesoporous silica was obtained using two methods: sol-gel and incipient impregnation, in each case also varying the percentage of niobium incorporation. The synthesized Nb-MCM-41 ceramic powders were characterized using the spectroscopic techniques of infrared spectroscopy (IR), Raman spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The photodegradation capacity of the powders was studied using the organic molecule, methylene blue. The effect of both the method of synthesis and the percentage of niobium present in the sample on the photodegradation action of the solids was determined. The mesoporous Nb-MCM-41 that produced the greatest photodegradation response was obtained using the sol-gel method and 20% niobium incorporation.
关键词： synthesis,mesoporous,niobium,photodegradation
更新于2025-09-10 09:29:36
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Association between seasonal serum folate levels and ultraviolet radiation
摘要： UV radiation has been consistently reported to cause folate photodegradation in vitro and in human skin. Seasonal variations in UV radiation might explain seasonal changes in folate levels in blood. Yet, few studies have addressed this phenomenon. The main objective of this study was to investigate whether a relationship exists between seasonal variations in serum folate levels in a population of Spain (Latitude: 36° 41' 6.88''; Longitude: 4° 30' 0.64'') and the annual variations of solar ultraviolet reached in the localization. From a sample of 118831 serum folate determinations, two studies were performed. The first one, which included all subjects, showed a decreased in mean folate concentrations in all seasons with respect to winter with lower values in summer. The risk of folate deficiency was 1.37 times greater in summer than in winter (95%CI: 1.29-1.46). In the second study, subjects with a first folate determination in winter and a second one in summer were 3.32 more likely to develop folate deficiency than those with a first folate determination in summer and a second one in winter (95%CI: 1.55 to 7.11). Folate levels showed a seasonal variation inversely related to solar total UV radiation reached in our location, with maximum daily doses of 5000 J m-2 reached in June. A gradual increase in percentage of folate deficiency is observed since spring. So, patients with folate levels close to deficiency are at a higher risk of having folate deficiency in summer.
关键词： folic acid,solar ultraviolet radiation,seasonal variation,folate deficiency,folate,photodegradation,population study
更新于2025-09-09 09:28:46
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Dark recovery of photodegraded dissolved organic matter as a source of a protein-like fluorophore in natural waters
摘要： Excitation-emission matrix (EEM) fluorescence spectroscopy is being widely used to characterize dissolved organic matter in aquatic environments. The main types of fluorophores in natural waters, defined by this technique, are humic-like and the protein-like ones. The latter is generally thought to be of biological origin. In this study, we show that the emergence of the protein-like fluorophore may be the result of DOM phototransformation. Samples of natural waters were irradiated using ultraviolet radiation in the solar wavelength range. Their EMM spectra were recorded before and directly after irradiation, and after 72 h long dark storage. Fluorescence of the photodegraded water samples partially recovered during the storage. The highest increase in fluorescence was observed in the spectral range ascribed to the protein-like fluorophore. It suggests that microbial production is not the only source of this component of DOM.
关键词： Dissolved organic matter,Photodegradation,Protein-like fluorescence
更新于2025-09-09 09:28:46
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Photoactivity of Ag/TiO2 Microsphere by One-Step Hydrothermal Method
摘要： Ag/TiO2 microsphere photocatalyst was prepared via one step hydrothermal method and prepared catalyst was used for photodegradation of rhodamine B under visible light. The Ag/TiO2 catalyst was characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed Ag was uniformly distributed in the titanium matrix. The 6 % Ag doped TiO2 catalyst had the higher photoactivity than other proportion to degrade rhodamine B 86.6 % within 60 min under visible light. The Ag doped TiO2 also had the good activity under solar light cut off UV light.
关键词： Ag doped TiO2,Photodegradation,Hydrothermal method,Microsphere
更新于2025-09-09 09:28:46
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Visible light accelerates the ultraviolet A-induced degradation of eumelanin and pheomelanin
摘要： Exposure to excess ultraviolet (UV) A radiation induces the degradation/modification of both eumelanin and pheomelanin that may be deleterious to pigmented tissues. Although the spectral distribution of solar energy comprises nearly half of visible light (VL), few studies have been conducted to examine the role of VL in the photodegradation of both types of melanin, either VL alone or in combination with UVA. In this study, we examined the effects of physiological doses of VL (150 to 300 J/cm2) alone or in combination with a physiological dose of UVA (20 J/cm2) in normal human epidermal melanocytes. The degradation/modification of melanin structures were evaluated by our chemical degradation – HPLC methods. The results show that VL accelerates UVA-induced changes in the structural features of both eumelanin and pheomelanin, although VL or UVA alone induced only minor changes in melanin structure. The differential spectral method provides support for the additive effects of VL.
关键词： visible light,eumelanin,photodegradation,pheomelanin,ultraviolet A
更新于2025-09-09 09:28:46
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Kinetics, mechanism, and identification of photodegradation products of phenazine-1-carboxylic acid
摘要： Phenazine-1-carboxylic acid (PCA) is a broad-spectrum antibiotic against many plant pathogens, produced by Pseudomonas and other species. The biosynthesis and regulation of PCA has been well documented, but there is no report about its photochemical properties. Herein, the photodegradation of PCA was carried out in an aqueous solution under the irradiation of visible light to investigate the kinetics, mechanism, and identification of photodegradation products of PCA. Results revealed that photodegradation of PCA accorded well with first-order reaction kinetics. The measured half-life of PCA was 2.2 days at pH 5.0 and increased to 37.6 days at pH 6.8 when exposed to visible light. When oxygen was removed from its solution, the half-life of PCA was doubled. Different units of superoxide dismutase (SOD) enzyme (i.e. 0 units, 300 units, and 3000 units) and varying concentrations of sodium azide (i.e. 0 mg, 5 mg, 10 mg, and 20 mg) were used to decipher the mechanism for PCA photodegradation. Hydroxyl PCA and hydroxy phenazine were tentatively identified as the degradation products of PCA photodegradation process by high-performance liquid chromatography (HPLC). The obtained degradation products were further characterized and confirmed by HPLC-mass spectrometry and LC-MS/MS-based analytical approaches. In conclusion, the degradation of PCA was found to be light dependent, which could be accelerated by hydrogen ion and oxidant in the solution. The results suggest that PCA was more stable when stored in a neutral or alkaline environment or in the dark. Therefore, it is important to modify the PCA structure or use a suitable dosage for its broad-spectrum applications.
关键词： First-order kinetics,Biological pesticide,Photodegradation,Phenazine-1-carboxylic acid,LC-MS,Degradation products
更新于2025-09-09 09:28:46
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A Review on BiOX (X= Cl, Br and I) Nano-/Microstructures for Their Photocatalytic Applications
摘要： In the recent past, bismuth oxyhalides (BiOX) have been widely used for the photocatalytic degradation of the organic pollutants and other environmental remediation because of their higher stability, economic viability, nontoxicity and effective charge separation. We begin with the review of the different approaches adopted so far for BiOX (X = Cl, Br, and I) synthesis and a study of their photocatalytic performances under UV and visible light towards the various organic as well as inorganic pollutants. Later on, a study on further enhancement of the ef?ciency of BiOX under UV and visible light irradiation using recent advancements would be presented. The new approaches involve controlled morphology by forming composite and hybrid materials with other semiconductors and also doping with other metals and nonmetals that would undoubtedly be bene?cial in the interfacial charge transfer and ef?cient inhibition of the photo-generated species. Herein, we would also exploit the recent developments in the research strategies for enhancing photocatalytic activity of BiOX.
关键词： Pollutants,Photocatalysts,Functionalization,Stability,Bismuth Oxyhalides,Heterostructures,Photogenerated Species,Environmental Remediation,Composites,Photodegradation,Visible Light
更新于2025-09-09 09:28:46
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N-S Codoped Cerium-Cobalt Oxide Bimetal Nanoparticles Catalyzed Photodegradation of Brilliant Green and Fast Green
摘要： Cerium-cobalt oxide bimetal nanoparticles were synthesized using wet precipitation method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalyzed degradation of brilliant green and fast green dyes were studied using CeCoO3 bimetallic nanoparticles spectrophotometrically. Photocatalytic activity has been tested in the reaction of these dyes under visible irradiation. It was revealed that doping enhanced the photocatalytic activity at low doping levels but reduced the activity at high doping levels. Various parameters like amount of semiconductor, pH, light intensity, dye concentration, % of dopant were also studied. The rate of reaction followed pseudo-first order kinetics.
关键词： Nanoparticles,Fast green,Brilliant green,Cerium-Cobalt oxide,Photodegradation
更新于2025-09-09 09:28:46
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Doping effects on mixed-phase crystalline perovskite AxSr1?xFeO3?δ (A?=?Pr, Sm; 0?≤?x??≤?0.8) nanoparticles and their application for photodegradation of rhodamine B
摘要： A series of doped perovskite AxSr1?xFeO3?δ (A = Pr, Sm; 0 ≤ x ≤ 0.8) nanoparticles were synthesized using a solution combustion method. By doping lanthanide elements, the crystal phase of the perovskite SrFeO3?δ (SFO) changed from cubic to orthorhombic system. Phase transitions and mixed-phase components of prepared catalysts can be successfully controlled only by varying the mole ratio of A-site doping at 800 °C for 5 h. Compared with pure SFO, the Pr/Sm-doped SFO samples exhibited enhanced absorption capability especially in the visible light region. The band gap of Pr/Sm-doped SFO samples was gradually decreased and the BET surface area increased with the increase of the Pr and Sm dopant content. The perovskite AxSr1?xFeO3?δ (A = Pr, Sm; x = 0.6, 0.8) included mixed phases of cubic and orthorhombic crystallinity and exhibited better photocatalytic degradation of rhodamine B (RhB) than single cubic phase. The photodegradation efficiency of RhB was increased with an increasing amount of A-site doping.
关键词： Phase transition,Perovskite,Photocatalytic oxidation,Photodegradation,Mixed phases
更新于2025-09-09 09:28:46