Presence Of Ultraviolet Light Research Articles

Facile synthesis of ZnO nanoparticles by thermal decomposition of Schiff base complexes for the effective removal of organic pollutants in an aqueous medium

A series of mononuclear Schiff base transition metal complexes of the type [M(LS)(temed)] (where, M = Co(II), Ni(II), Cu(II), and Zn(II); LS = Schiff base ligand derived from L-leucine and Salicylaldehyde and co-ligand temed = N,N,N’N’- tetramethylethylenediamine) have been synthesized and characterized by spectroscopic studies such as Mass, NMR, UV–Visible, FT-IR, and TGA analysis. Spectral results reveal that the metal ions are coordinated to imine nitrogen, phenolic oxygen, and oxygen atom present in the carboxylate group of the Schiff base ligand and two nitrogen atoms from ligand (L2) temed. The scavenging activity of the complexes was carried out by the DPPH method with different concentrations, and all the complexes possesses good antioxidant activity in the range 58.93 to 78.79 %. Among them Zn(II) complex showed higher scavenging activity 78.79 % using 10 mg concentration. Furthermore, an investigation was conducted to assess the antibacterial properties of the complexes. It was observed that all of the metal complexes exhibited significant antimicrobial activity. Notably, the copper complex demonstrated enhanced activity, particularly against S. aureus and Mucor species, with zone of inhibition measurements of 19 mm and 20 mm, respectively. The Zn(II) complex has been used as a precursor to produce zinc oxide nanoparticles by the thermal decomposition method. ZnO nanoparticles have been characterized by powder X-ray diffraction (PXRD), UV–Vis spectroscopy techniques, scanning electron microscopy (SEM), FT-IR spectroscopy. The photocatalytic activity of zinc oxide nanoparticles was investigated in the presence of ultraviolet light. ZnO nanoparticles can efficiently catalyze the degradation of methyl orange, methylene blue, and rhodamine B in the aqueous suspension, and the highest percentage of degradation was observed against methylene blue (99 %). Furthermore, the impact of altering dye concentration, pH, catalyst quantity and kinetics on the photodegradation of model pollutant methylene blue was investigated.

Synthesis and photocatalytic degradation of an acid dye using factorial design

A new acid dye was synthesised from the reaction of 6-amno-2-(5-chloro-1,3-dioxoisoindolin-2yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione with J-acid. The synthesised dye was characterised by melting point, UV-visible absorption, FT-IR and 1H-NMR spectroscopy. The synthesised dye was stimulated and subjected to photodegradation using hydrogen peroxide (H2O2) as photocatalyst in the presence of ultraviolet light in a photo reactor. The rate of degradation of the dye solution was determined on the basis of absorbance measurement. Four factors such as dye concentration, pH of the solution, time of irradiation and catalyst loading were used as the operational parameters for the photo-degradation studies. The Minitab 17 software was used to determine the optimized conditions for the experiment. The main effects and interactions between factors were investigated and results analysed. The results for the optimization parameters in the photocatalytic degradation revealed the following conditions for the percentage degradation: Maximum degradation at 67.9 % with the desirability of 0.96462, dye concentration of 10 mg/L, catalyst loading of 2 mL, with the time of irradiation of 90 minutes at pH of 3.9 for the dye. This showed that (UV/H2O2) photocatalytic degradation of acid dyes using factorial design were effective and efficient technology which can be used in treatment of tannery and textile effluents.

Preparation of smart glue using strontium aluminate and polylactic acid oligomer grafted Arabic gum

An intelligent nanocomposite adhesive was developed to streamline the manufacturing process for long-lasting photoluminescent and hydrophobic consumer goods. The photoluminescent adhesive composite continued to emit light for up to 120 min after being exposed to darkness. Using lanthanide-activated strontium aluminate (LaSA) nanoparticles (NPs; 5–11 nm) homogeneously immobilized in the eco-friendly polylactic acid oligomer grafted Arabic gum (PLA/AG), a light-transmitting nanocomposite adhesive agent was created. The produced adhesives at various LaSA NPs concentrations exhibited excitation intensity at 365 nm and an emission wavelength at 518 nm. Afterglow phosphorescence or fluorescence was seen in the emission spectra, depending on the LaSA ratio. The photochromic effect was observed as the adhesive film switch color from translucent to green in the presence of ultraviolet light and greenish-yellow in the absence of light. The LaSA nanoparticles embedded in the polylactic acid oligomer grafted Arabic gum matrix improved the nanocomposite hydrophobicity and scratch resistance. Both of durability and photostability of the LaSA@PLA/AG nanocomposite were found to be exceptional. This work verified the viability of mass producing photoluminescent adhesive for a variety of smart uses such as smart windows, smart packaging, and safety directional signs in buildings.

Green synthesized ZnO nanoparticles by Saccharomyces cerevisiae and their antibacterial activity and photocatalytic degradation

AbstractMany research papers are currently being written about various methodologies for the green synthesis of ZnO nanoparticles. In this study, ZnO nanoparticles were prepared by green synthesis method using baker’s yeast (Saccharomyces cerevisiae). The characterization of the produced ZnO nanoparticles involved the utilization of XRD, FTIR, SEM, and TEM. The investigation involved the assessment of the antimicrobial potential and photocatalytic degradation efficacy of the synthesized materials through the utilization of Eriochrome Black T (EBT). The results indicate that the ZnO nanoparticles exhibit a spherical morphology, exhibiting diameters ranging from 13.0 to 20.0nm, with an average particle size of 15.0nm. The antimicrobial efficacy against (S. aureus) gram-positive and (E. coli) gram-negative bacteria was tested through the conduction of zone of inhibition (ZOI) and minimum inhibitory concentration (MIC) tests. This research focused on the study of the photocatalytic-degradation of EBT in the presence of ultraviolet light. The experiments focused on the impact of various factors, such as pH levels, initial EBT concentration, and nanocatalyst dosage, on the observed photocatalytic efficiency. In the in vitro ZOI and MIC results assay, it was observed that ZnO nanoparticles (NPs) exhibited greater efficacy against gram-positive S. aureus, with a ZOI measuring 23.1 mm and a MIC of 0.625 μg/ml. In contrast, the effectiveness of ZnO-NPs against gram-negative E. coli was comparatively lower, as indicated by a ZOI of 17.0 mm and a MIC of 1.250μg/ml. The greatest EBT elimination, which achieved 83.0% in equilibrium, was found employing 20.0mg of ZnO NPs at pH 3.0, according to the photocatalytic activity results. The synthetic ZnO NPs are powerful antibacterial agents that are effective against tested bacteria and may be used in the treatment of wastewater.

Correlation between the Experimental and Theoretical Photoelectrochemical Response of a WO3 Electrode for Efficient Water Splitting through the Implementation of an Artificial Neural Network

Since the discovery of photoelectrochemical (PEC) water splitting with titanium dioxide electrodes in the presence of ultraviolet light, much work has been conducted to build an effective PEC water splitting system and develop novel photoelectrodes. Using a facile and controllable electrodeposition method, a thin tungsten trioxide (WO3) film electrode onto a stainless steel (SS) substrate was synthetized. The effect of the deposition time on the structural, morphological, optical, and electrical properties of the as-grown WO3 thin films was assessed. XRD spectra of the obtained films reveal the polycrystalline nature of WO3 with a triclinic phase and exhibit a sharp transition to the (002) plane when the deposition time was extended beyond 10 min. The surface morphology showed a remarkable change in the grain size, thickness, and surface roughness when varying the deposition time. UV–Vis spectrophotometry revealed that the optical band gap values of WO3 decreased from 1.78 to 1.36 eV by extending the electrodeposition duration from 10 to 30 min, respectively. Notably, as indicated from the PEC measurements, the obtained photoelectrode exhibited the effects of the deposition time on the photocurrent density, and the maximum value obtained was around 0.07 mA cm−2 for the sample deposited at 10 min. Finally, this study presents for the first time an artificial neural network model to predict the PEC behavior of the prepared photoanode, with a highly satisfactory performance of less than 0.05% error. The low cost and simply synthetized WO3/SS electrode with superior electrochemical performance and the excellent correlation between the experimental and theoretical results demonstrate its potential for practical application in water splitting and hydrogen production.

Fabrication of Dual-Stimuli-Responsive Polymer Vesicles for Regulation of Enzymolysis Efficiency in A Cascade Reaction.

Enzymatic cascade reactions in confined microenvironments play important roles in cellular chemical transformation. Controlling enzymatic efficiency and eliminating substrate interference in cascade reactions is of great significance. To this end, a vesicle composed of poly(styrene-maleic anhydride-N-isopropylacrylamide)(P(S-M-NIP)) and functionalized with 1,2-bis(10,12- tricosadiynoyl)-sn-glycero-3-phosphocholine (DC89 PC) was designed herein. Based on the thermo-sensitive property of P(S-M-NIP) and the photo-responsive property of DC89 PC, a serial of dual-stimuli-responsive nanoreactors was constructed via enzymes encapsulation to tune their enzymolysis efficiencies. A kinetics study of the glucose oxidase-encapsulated nanoreactor indicated that its enzymolysis velocity increased 2.1- and 1.6-fold under heating and the ultraviolet (UV)-light irradiation, respectively. Consequently, an enzymatic cascade reaction in the proposed enzyme reactor encapsulated with β-galactosidase and glucose oxidase was investigated. The results revealed a 2.9-fold enhancement in enzymolysis efficiency by changing the ambient temperature under UV irradiation. The dual-stimuli-responsive polymer vesicles could also eliminate H2 O2 interference during the enzymatic cascade reaction. The vesicles demonstrated potential for switch-membrane-permeability, while, the confined microenvironment played a key role in regulating the reactions upon the temperature change and the presence of UV light. Our synthetic multi-organelle-like system provides a new way to mimic the control of cascade reaction catalytic processes by programming the "open/close" sates of the nanocapsules.

Photo-oxidation degradation of metronidazole in hematite/sulfite system: Mechanism, kinetic, degradation pathway

In this study, the decomposition of metronidazole (MTZ) in the hematite (α-Fe2O3)/sulfite system and in the presence of ultraviolet light was investigated. Based on transmission electron microscopy (TEM) and field scanning electron microscopy (SEM) analysis, hematite nanoparticles were included an average diameter of 80 nm. The results showed the process performance under the acidic and natural conditions was very high, as the destructive performances of MTZ (after 5 min of reaction), at pHs of 3 and 7.5 were 80 % and 92 %, respectively. The efficiency of each of the UV/sulfite (US) and UV/hematite (UH) systems in the degradation of metronidazole was 30 % and 27 %, respectively, which indicated the very low efficiency of these systems when each was used alone. Enhanced performance was observed when both hematite/sulfite agents were simultaneously exposed to UV, so that more than 92 % of metronidazole was degraded under the selected conditions (sulfite/hematite/MTZ molar ratio of 1:3: MTZ concentration and pH of 7.5 after 5 min of reaction). The rate of MTZ destruction in one min (robs (mg L−1 min)) indicated the supremacy of UHS process over UH and US processes. It was found the anions in the water matrix affect the efficiency of the system. Tests to investigate the active radical species in the reaction medium proved the importance of the role of the two hydroxyl and sulfate radicals in MTZ decomposition. A comparison of the total cost, energy consumed, and robs between the different systems, revealed UHS system can be considered as an economically acceptable and efficient process in the destructive of MTZ. Based on analysis done, the final products of MTZ degradation using UHS process were characterized to be Acetaldehyde, 1H-imidazole, Hydroxy acetonitrile, Aminoacetonitrile, Glycine, Isoamyl benzyl ether, Alanine and Acetic acids.

Remove safranin dye from the aqueous solution using ZnO stabilized on zeolite in the presence of ultraviolet light

Remove safranin dye from the aqueous solution using ZnO stabilized on zeolite in the presence of ultraviolet light

Room Temperature Detection of Hydrogen Peroxide Vapor by Fe2O3:ZnO Nanograins.

In this report, a Fe2O3:ZnO sputtering target and a nanograins-based sensor were developed for the room temperature (RT) detection of hydrogen peroxide vapor (HPV) using the solid-state reaction method and the radio frequency (RF) magnetron sputtering technique, respectively. The characterization of the synthesized sputtering target and the obtained nanostructured film was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) analyses. The SEM and TEM images of the film revealed its homogeneous granular structure, with a grain size of 10-30 nm and an interplanar spacing of Fe2O3 and ZnO, respectively. EDX spectroscopy presented the real concentrations of Zn in the target material and in the film (21.2 wt.% and 19.4 wt.%, respectively), with a uniform distribution of O, Al, Zn, and Fe elements in the e-mapped images of the Fe2O3:ZnO film. The gas sensing behavior was investigated in the temperature range of 25-250 °C with regards to the 1.5-56 ppm HPV concentrations, with and without ultraviolet (UV) irradiation. The presence of UV light on the Fe2O3:ZnO surface at RT reduced a low detection limit from 3 ppm to 1.5 ppm, which corresponded to a response value of 12, with the sensor's response and recovery times of 91 s and 482 s, respectively. The obtained promising results are attributed to the improved characteristics of the Fe2O3:ZnO composite material, which will enable its use in multifunctional sensor systems and medical diagnostic devices.

Enhanced UV-light active α-Bi2O3 nanoparticles for the removal of methyl orange and ciprofloxacin

• UV light-induced pollutant degradation was completely degraded by bismuth trioxide at ∼87% and 95∼ after 100 and 140 min for methyl orange and ciprofloxacin. • According to the TOC report confirmed by the mass spectrometry spectrum, most pollutants were converted into less toxic products after being exposed. • As a consequence, we can draw the conclusion that Bismuth Trioxide is the perfect candidate for the degradation of pollutants due to the fact that it is less costly, is simple to synthesize, and has a reasonable degradation rate. • Additionally, the photocatalyst can be reused more than four times without significantly altering its degradation rate. This study successfully synthesized α-Bi 2 O 3 nanoparticles using a grinding method. XRD, FT-IR, UV-Vis DRS, and Raman spectroscopy were used to determine the structure and optical properties of the sample. The XRD and Raman results of the Bismuth Trioxide prepared led us to believe that it had a hexagonal structure. Furthermore, the EDXRF and EDX results indicate that the synthesized material is highly pure and impurity-free. In the presence of ultraviolet light, Bi 2 O 3 nanoparticles exhibit superior photocatalytic activity for the degradation of Methyl Orange (MO) and Ciprofloxacin (CIP). It is estimated that 87% of CIP can be removed after 100 minutes and 95% of MO after 150 minutes. In accordance with the TOC removal report, 67.73% of CIP had been removed after 200 minutes and 77.86% had been removed after 280 minutes. Additionally, a four-cycle treatment did not significantly change the activity of the catalyst.

UV illumination control and enhancement of heat transfer during pool boiling process

An increasing number of studies have focused on controlling the boiling flow field using external effects. This study is the first to propose a transition of bubble nucleation by triggering titanium dioxide (TiO2) surfaces with ultraviolet (UV) illumination during the pool boiling process. In the presence of UV light, the wettability of the TiO2 surface changed from hydrophobic to hydrophilic owing to photocatalysis. An opportune moment to activate the surface wettability transition using UV illumination occurred during the boiling process of isolated bubbles. High-speed camera images showed that the transition of the surface wettability with UV illumination changed the liquid vapor dynamics in the pool and affected the boiling heat transfer performance. The TiO2-coated surfaces of the test samples, upon UV illumination, showed an enhancement of 72% in the critical heat flux (CHF) and 49% in the heat transfer coefficient (HTC) compared with plain copper surfaces.

Optical and photocatalytic application of hydrothermally synthesized crystalline TiO2 nanostructures

AbstractIn this paper, the hydrothermal synthesis of TiO2 nanostructures was analyzed for their structural, morphological, elemental, and optical Properties. X‐ray diffraction (XRD) confirms a highly crystalline nature and reveals that the TiO2 nanocrystals crystallize in the body‐centered tetragonal phase. Scanning electron microscopy (SEM) results show that all the samples are composed of microspheres that are formed from the agglomeration of smaller nanoparticles. The size of the microspheres varies from sample to sample and has a direct relation to the volume of the precursors used. Energy‐dispersive X‐ray analysis (EDAX) shows that the synthesized materials are in good stoichiometry with uniform distribution of the constituents throughout the sample. Fourier transform infrared spectrum of different samples showed a 100% transmittance peak in the 500 to 1000 cm−1 region. Ultraviolet (UV) and visible spectroscopy shows that the material has a good absorption in the visible region and is suitable for photocatalysis. The bandgap of the samples was determined by using the Tauc plot. The synthesized material was used for the photocatalytic degradation of methyl red (MR), a hazardous dye. The 95% degradation of MR occurred in the presence of UV light.

Synthesis and characterization of a g-C3N4/TiO2-ZnO nanostructure for photocatalytic degradation of methylene blue

In this study, graphitic carbon nitride (g-C3N4) nanostructures with different molar ratios of ZnO and TiO2 (i.e. g-C3N4/TiO2, g-C3N4/ZnO, and g-C3N4/TiO2-ZnO) were synthesized. The synthesized samples were characterized using field-emission scanning electron microscopy (FE-SEM), x-ray diffraction, Brunauer–Emmett–Teller (BET) analysis, and ultraviolet (UV)–visible diffuse reflectance spectroscopy (UV-vis-DRS) techniques. The FE-SEM images showed the surface morphology of each sample. The UV-vis-DRS results indicated that the bandgap of TiO2 was reduced by adding g-C3N4 and different molar ratios of ZnO. The results obtained from BET analysis confirmed that the surface area of the g-C3N4/TiO2-ZnO (1:10) nanostructure was 97.494 cm2 g−1, which was comparatively higher than other nanostructures, and became suitable for photocatalytic activity. The photocatalytic activity of the g-C3N4/TiO2-ZnO nanostructure was performed by photo-degradation of methylene blue (MB) dye under simulated solar light. The results of the photocatalytic activity showed that the synthesized nanostructure had good degradation under UV and visible light irradiation by 94.6% and 62.4%, respectively. Also, the kinetics of the photocatalytic degradation confirmed that degradation of MB dye in the presence of UV light was faster than visible light. Furthermore, a study of the reusability of the nanostructure exhibited good photo-stability and activity after six runs.

Removal of malathion insecticide from aqueous solution by the integration of persulfate process and magnetite nanoparticles loaded on carbon (Fe3O4@CNT) in the presence of ultraviolet radiation

Malathion is one of the most common insecticides in the world, and its persistence in aquatic environments poses a serious threat to human health and ecosystems. In this study, a combined process of persulfate and magnetite nanoparticles loaded on carbon (Fe3O4@CNT) in the presence of ultraviolet light was used to decompose malathion as a chemically resistant compound in contaminated water. Fe3O4@CNT was synthesized, and then characterized and characterized using XRD refraction, electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller. In this hybrid process, the decomposition of malathion occurred at pH =5, 2 mmol persulfate, and 0.4 g of Fe3O4@CNT at 60 minutes. The results of sconing experiments showed that sulfate, hydroxyl, and ultraviolet radicals are involved in the optimum decomposition of malathion and this process was able to purify the malathion from the water.

Synthesis of phenanthroline-based ligand and its UV activable tetracarbonyl photoCORMs based on chromium, molybdenum, and tungsten as cytotoxic and antimicrobial agents

A phenanthroline-based ligand L1 ((((1,10-phenanthrolin-5-yl)imino)methyl)-6-methoxyphenol) was synthesized and reacted with chromium, molybdenum, and tungsten hexacarbonyl to form ultraviolet (UV) activable photoCORMs C1, M1, and T1, respectively. All compounds were characterized via IR, 1H-NMR, 13C-NMR, and CHN elemental analyses, and the X-ray crystal structures of L1 and M1 were determined. The half-life of the photoCORMs decreased with an increasing concentration and the rate of CO release increased in the order of T1 < M1 < C1, with C1 having the shortest half-life (7.4 seconds at 60 µM). Both M1 and T1 displayed remarkable stability in 10% DMSO-PBS solution over 48 hours in the dark, whereas C1 showed signs of decomposition. In the absence of UV, all compounds exhibited appreciable cytotoxicity against human-derived colorectal adenocarcinoma HCT 116, with T1 being the most cytotoxic (IC50 5.49 µM). The cytotoxicity of the photoCORMs were elevated substantially after brief exposure to UV light (365 nm), with that of C1 having the most drastic improvement (IC50 from 9.98 to 1.24 µM). Moreover, all compounds were selective towards HCT 116 while being relatively less toxic against normal human colon fibroblast CCD-18Co. Furthermore, all compounds were generally not active in the bactericidal and growth inhibitory effects against the tested bacteria and fungi when UV light is absent, except for L1 that exhibited notable activity against B. cereus, B. subtilis, E. coli, K. pneumoniae, and S. flexneri (MIC ≤ 12.5 mg/ml). In contrast, the photoCORMs showed significant improvement in the growth inhibitory effect against several microbes in the presence of UV light, viz., B. cereus, B. subtilis, methicillin-sensitive S. aureus (ATCC 29213 and 33591 strain), and S. flexneri, while no notable improvement in the bactericidal effect was shown.

Decomposition of lignin compounds from oil palm empty fruit bunch using ilmenite

Decomposition of lignin compounds into monomers from oil palm empty fruit bunches (OPEFB)has been successfully carried out. The purpose of this study was to determine the use of ilmenite as a lignin decomposerof OPEFB and to analyze the compounds produced using GC-MS method. The stages of the study consisted of preparation of ilmenite, pretreatment process of OPEFB, characterization of lignin isolates using FTIR, analysis of lignin content by UV-Vis, and photodegradation of lignin by GC-MS. Ilmenitewas known to have a potential for decomposing the lignin compound through a photodegradation reaction, in the presence of ultraviolet light. The results of this study indicated that a time of five hours decomposition could have degraded lignin up to 50%. The longer the degradation time, the more lignin was degraded to produce materials in the form of phenolic compounds, furan compounds, benzene derivatives and carbon compound derivatives from lignin monomers. One of the benzene derivatives obtained was 3,4-di (methoxycarbonyl) benzoic acid (C11H10O6).

The Repurposing of Acetylsalicylic Acid as a Photosensitiser to Inactivate the Growth of Cryptococcal Cells.

Photodynamic treatment (PDT) is often successful when used against aerobic microbes, given their natural susceptibility to oxidative damage. To this end, the current study aimed to explore the photodynamic action of acetylsalicylic acid (ASA; aspirin, which is commonly used to treat non-infectious ailments), when administered to respiring cryptococcal cells. The treatment of cryptococcal cells, i.e., exposure to 0.5 or 1 mM of ASA in the presence of ultraviolet light (UVL) for 10 min, resulted in a significant (p < 0.05) reduction in the growth of tested cells when compared to non-treated (non-Rx) cells, i.e., no ASA and no UVL. The treated cells were also characterised by diseased mitochondria, which is crucial for the survival of respiring cells, as observed by a significant (p < 0.05) loss of mitochondrial membrane potential (ΔΨM) and significant (p < 0.05) accumulation of reactive oxygen species (ROS) when compared to non-Rx cells. Moreover, the photolytic products of acetylsalicylic acid altered the ultrastructural appearance of treated cells as well as limited the expression levels of the capsular-associated gene, CAP64, when compared to non-Rx cells. The results of the study highlight the potential use of ASA as a photosensitiser that is effective for controlling the growth of cryptococcal cells. Potentially, this treatment can also be used as an adjuvant, to complement and support the usage of current anti-microbial agents.

Enhanced oxidative removal of NO by UV/in situ Fenton: Factors, kinetics and simulation.

A series of experiments on the oxidative removal of NO from flue gas using a novel in situ Fenton (IF) system was performed in the presence of ultraviolet light (UV). The comparison tests revealed that the in situ Fenton system facilitated by UV (UV/IF) has a better oxidation ability of NO than that of the IF system due to the photochemical effect on the generation of oxidative species like (OH). Both of the aforementioned oxidation efficiencies were higher than that of the conventional Fenton system (CF) depending on the premix of Fe2+ and H2O2 solutions, which attribute to the improvement of (OH) yield and valid utilization with continuous addition of fresh reagents and UV radiation. In follow-up experiments, the effects of UV power, gas flow rate, reagent temperature, Fe2+/H2O2 molar ratio, initial pH, initial concentration of NO and SO2 and volume fraction O2 and CO2 on the oxidative removal of NO by UV/IF method were investigated respectively. Moreover, the results of kinetic analysis indicated that NO oxidation was confirmed to have a pseudo-first-order kinetics pattern. The rate constants decreased slightly with increasing liquid temperature, and then the apparent activation energy of NO oxidation reactions in the UV/IF system was calculated as -5.62kJ/mol by the Arrhenius equation. Furthermore, the reaction mechanism and application prospects concerning NO oxidative removal by using the UV/IF system was speculated in brief. Finally, the computational fluid dynamics (CFD) simulations revealed that the improvement of axial and radial gas hold-up would enhance the gas-liquid contact and accelerate the oxidation reactions on the interface. In addition to reasonable control of process parameters, the optimization of reactor interior structure needs to be carried out via CFD simulation and experimental validation in future research, both are favourable to promote the NO oxidation efficiency and large-scale development of this technology.

Tartrazine removal by ZnO nanoparticles and a zeolite-ZnO nanoparticles composite and the phytotoxicity of ZnO nanoparticles

ZnO nanoparticles (nanZnO) and a zeolite-ZnO nanoparticles composite (Ze-nanZnO) were prepared and characterized. These materials were used for the removal of tartrazine from aqueous solutions by an adsorption-photocatalysis coupled process. The adsorption using nanZnO showed a rapid decrease of the concentration of tartrazine and the adsorption by using the composite Ze-nanZnO was slower. The degradation of tartrazine by using both materials in the presence of ultraviolet light seems to be a highly efficient process for both materials, 87 and 81% degradation were observed for nanZnO and Ze-nanZnO respectively, although the first material seems to be more efficient than the second, this first material is difficult to remove from the aqueous solution after the process. The mineralization was monitored by measuring the total organic carbon at different contact and irradiations times. The degradation of the dye was high between 85 and 90%, higher degradation was observed using Ze-nanZnO as catalyst than nanZnO. “Lactuca sativa” species suffer “low toxicity” when they are in contact with solutions containing the dye and solutions that were in contact with nanZnO. • Tartrazine was removed from aqueous solutions by an adsorption-photocatalysis coupled process. • Degradation of tartrazine by both materials in the presence of ultraviolet light is efficient. • The degradation of the dye was high between 85 and 90%. • “Lactuca sativa” species suffer “low toxicity” when in contact with nanZnO.

A novel zero valent metal bismuth for bromate removal: direct and ultraviolet enhanced reduction.

Bromate (BrO3−) is a carcinogenic and genotoxic by-product of the ozone disinfection process. In this study, a new zero-valent metal, bismuth, was used to reduce bromate. Bismuth samples were prepared by a solvothermal method and characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The morphology of the bismuth powder was microspheres assembled with dense nanosheets. The kinetics of the direct bromate reduction by bismuth accorded with the pseudo-first-order kinetics model. The rate coefficients of the initial bromate concentration of 1.00 mg L−1, 2.50 mg L−1, 5.00 mg L−1 were identically close to 0.08 min−1. For 0.20 mg L−1, a reaction rate coefficient near 0.10 min−1 was obtained. The reducing products of bromate included bromide ions (Br−) and bismuth oxybromides. The bromate removal efficiency was enhanced remarkably in the presence of ultraviolet (UV) light, and the corresponding kinetic coefficient was 4 times higher than that of direct reduction. The mechanism of ultraviolet enhancement was analyzed by diffuse reflectance spectroscopy (DRS), the density functional theory (DFT) calculation, open circuit potential (OCP) analysis, photocurrent measurement and linear sweep voltammetry (LSV). Besides, the influence of dissolved oxygen (DO) on bromate reduction efficiency and the sustainability of the as-prepared sample were investigated. DO inhibited the reduction rate obviously, but showed a slight effect on the formation of bromide ions. In the long-term periodic experiments, the kinetic coefficient decay occurred in both direct (without UV irradiation) and ultraviolet assisted bromate reduction. However, the kinetic coefficient of UV-assisted reduction (0.115 min−1) was about 2 times higher than that of the direct reduction in the last cycle of periodic experiments. In conclusion, the novel bromate reduction strategy based on the zero-valent bismuth metal material has been proved efficient and sustainable, which contributes to the development of drinking water treatment technologies.