In this study,three-dimensional porous magnesium ferrite/titanium dioxide/reduced graphene oxide(Mg Fe_2O_(4)-GM/TiO_(2)/rGO(MGTG))was successfully synthesized via green and hydrothermal-supported co-precipitation met...In this study,three-dimensional porous magnesium ferrite/titanium dioxide/reduced graphene oxide(Mg Fe_2O_(4)-GM/TiO_(2)/rGO(MGTG))was successfully synthesized via green and hydrothermal-supported co-precipitation methods using the extract of Garcinia mangostana(G.mangostana)as a reducing agent.The characterization results indicate the successful formation of the nano/micro Mg Fe_(2)O_(4)(MFO)and TiO_(2) on the structure of the reduced graphene oxide(rGO),which can also act as efficient support,alleviating the agglomeration of the nano/micro MFO and TiO_(2).The synergic effects of the adsorption and photodegradation activity of the material were investigated according to the removal of crystal violet(CV)under ultraviolet light.The effects of catalyst dosage,CV concentration,and p H on the CV removal efficiency of the MGTG were also investigated.According to the results,the CV photodegradation of the MGTG-200 corresponded to the pseudo-first-order kinetic model.The reusability of the material after 10 cycles also showed a removal efficiency of 92%.This happened because the materials can easily be recollected using external magnets.In addition,according to the effects of different free radicals·O_(2)^(-),h^(+),and·OH on the photodegradation process,the photocatalysis mechanism of the MGTG was also thoroughly suggested.The antibacterial efficiency of the MGTG was also evaluated according to the inhibition of the Gram-positive bacteria strain Staphylococcus aureus(S.aureus).Concurrently,the antibacterial mechanism of the fabricated material was also proposed.These results confirm that the prepared material can be potentially employed in a wide range of applications,including wastewater treatment and antibacterial activity.展开更多
Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein th...Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein the impurity level observed around 0.1% well below the threshold 0.5%. The approach to identify anonymous species was adopted as first to generate the impurity in sample, isolate, enrich and was subjected to LC-MS/MS and NMR for spectral studies. Based on the spectral data the anonymous species were identified as a “Lumibudesonide’’ ((5aR,5bS,5cS,6S,7aS,7bS,10aR,11aS,11bS)-6-hydroxy-7b-(2-hydroxyacetyl)-5b,7a-dimethyl-9-propyl 1,5a,5b,5c,6,7,7a,7b,10a,11,11a,11b dodecahydrocyclopenta[2'',3'']cyclopropa [1'',2'':3', 4']benzo [1',2':4,5]indeno [1,2-d][1,3]dioxol-5(2H)-one), which is observed in photolysis of Budesonide.展开更多
The emerging contaminants(ECs)are organic compounds including pharmaceuticals.These products are consumed in large quantities,favoring their continuous entrance to the environment and affecting the health of living be...The emerging contaminants(ECs)are organic compounds including pharmaceuticals.These products are consumed in large quantities,favoring their continuous entrance to the environment and affecting the health of living beings.Diclofenac is a non-steroidal anti-inflammatory drug with analgesic properties of prolonged release.It is the commonest postoperative analgesic,and it is highly consumed without prescription.In recent years,the capability of microalgae to remove pharmaceuticals in water has been tested as a promising tool.In this work,the removal efficiency of diclofenac(16µg/mL)by the microalga Nannochloropsis oculata CCAP 186/7 was evaluated.The major nutrient concentrations in Bold’s Basal Medium were modified(nitrogen and carbon:50 and 100%of their original concentration)to know their effect in the removal of diclofenac.Drug degradation by light was also evaluated.The maximum removal capacity of diclofenac in the medium was 68.8%.The percentage of diclofenac adsorbed on the cell wall was between 6 and 12.7%.Around 23.6%of diclofenac was degraded by light after 18 days.N.oculata did not show growth inhibition due to the presence of diclofenac.The results obtained point to the promissory application of N.oculata as a bioremediation system for diclofenac removal.展开更多
The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the ...The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the photodegradation behaviors of EE2 in the UV/H2O2 process.The results indicated that the addition of coexisting substances can influence the photodegradation behaviors of EE2 and it also follows the first-order kinetics.The acidic (pH 2-4) and alkaline (pH 10-12) medium benefit the photodegradation of EE2,but the photodegradation rate constant of EE2 keeps almost constant in the pH value of 4-10.The addition of anions,such as HCO3-,Cl-and NO3-,can inhibit the photodegradation of EE2,and the rate constant has a negative linear relationship with the concentration of the anions.However,the reduction degrees vary with the anions kinds,and the inhibition effect of the three anions is in the order of HCO3->NO3->Cl-.Addition of 5 mg/L methanol and bisphenol A can reduce the photodegradation rate constant of EE2by 84.31% and 72%,respectively.By comparison,the retardant effect of methanol is much more evident.In the studied concentrations range,the photodegradation rate constant of EE2 is the unary quadratic function of the organic compounds concentrations.展开更多
The photodegradation of irradiated thin films of poly (para-methylstyrene) with 265 nm radiations in the presence of airand as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR Spect...The photodegradation of irradiated thin films of poly (para-methylstyrene) with 265 nm radiations in the presence of airand as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR Spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on stability of poly (para-methylstyrene) towards irradiations was also investigated. Blending with phthalate plasticizers was found to cause a higher efficiency of photodegradation than that obtained in doping with terephthalate plasticizers. The intensity of absorption was also found to increase with time of irradiation and in change in the shape of the spectra at longer wavelength, thus indicating a possibility of photodegradation of polymer chains. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, shows a predominant absorption associated with carbonyl compounds with 1740 cm-1. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, have provided an evidence for the photodegradation as well as photo-oxidation of polymeric chains. The presence of the plasticizer in the polymer backbone was found to accelerate the photodegradation of polymeric chains.展开更多
The relationship between chemical structures and photodegradation activity of 12 PAHs is studied using DFT and HF methods, and stepwise multiple linear regression analysis method. The equilibrium geometries and vibrat...The relationship between chemical structures and photodegradation activity of 12 PAHs is studied using DFT and HF methods, and stepwise multiple linear regression analysis method. The equilibrium geometries and vibration frequency have been investigated by considering Solvent effects using a selfconsistent reaction field based on the polarizable continuum model. With DFT and HF methods, different quantum chemical structural descriptors are obtained by quantum chemical calculation and the results with DFT method are better for QSAR model. It is concluded that the photodegradation activity is closely related to its molecular structure. In the regression analysis, the main factors affecting photodegradation rate include the energy of the highest occupied orbital EHOMO and the number of six-carbon benzene ring N1, and the QSAR model successfully established is logkb = 6.046 + 54.830EHOMO + 0.272N1. Statistical evaluation of the developed QSAR shows that the relationships are statistically significant and the model has good predictive ability. EHOMO is the most important factor influcing the photodegradation of PAHs, because the higher EHOMO is, the more easily electron will be excited and the more easily molecular will be degraded. Comparison of the photodegradation of PAHs with their biodegradation shows that the committed step of biodegradation is that the effects of microorganisms make the chemical bond break, while in the committed step of photodegradation PAHs eject electrons.展开更多
The biodegradation behavior in vitro and in vivo of polycaprolactone-poly (ethylene glycol) block copolymer (PCE) was reported in detail. In this paper, photodegradation test of PCE was performed by exposure to UV lig...The biodegradation behavior in vitro and in vivo of polycaprolactone-poly (ethylene glycol) block copolymer (PCE) was reported in detail. In this paper, photodegradation test of PCE was performed by exposure to UV light The mechanical properties and the inherent viscosity of PCE samples which are subjected to photodegradation were determined. The experimental results indicated that poly (ethylene glycol) (PEO) segment in PCE copolymer is photosensitive. The photodegra-dation rate of the PCE was increased with increasing poly (ethylene glycol) content.展开更多
Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional waste...Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants.These two models were designated for(1)contaminants with high photolytic rates or high photolytic quantum yields,whose photodegradation is unlikely to be enhanced by aquatic photosensitisers;and(2)contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis.The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples,simulated solar experiments in the laboratory,and transfer of the laboratory results to realise water treatment using the prediction models.Although similar models have been widely used for laboratory studies,this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters.展开更多
Semiconductor photocatalysis is a novel highly efficient and low-cost method for removing organic pollutants from wastewater.However,the photoreduction performance of semiconductors on organic pollutants is limited du...Semiconductor photocatalysis is a novel highly efficient and low-cost method for removing organic pollutants from wastewater.However,the photoreduction performance of semiconductors on organic pollutants is limited due to the weak absorption of visible light caused by its wide band gap and low carrier utilization rate resulting from severe electron-holes recombination.In the present study,flower-like NH_(2)-UiO-66(NU66)/ZnO nanocomposites were prepared using a facile method and exhibited high efficiency under visible light driven photocatalysts.The X-ray diffractometer(XRD),scanning electron microscope(SEM),transmitor electron microscope(TEM),and X-ray photoelectron spectroscopy(XPS)were used to characterize the prepared samples,indicating that NU66/ZnO was successfully synthesized.The photocatalytic activity of the prepared NU66/ZnO nanocomposites was determined by measuring the photodegradation of methylene blue(MB)and malachite green(MG)under visible-light irradiation.The optimal nanocomposite loading of 5%wt NU66 to NU66/ZnO demonstrated the highest photocatalytic activity for the degradation of MB.The photocatalytic activity of a 5%NU66/ZnO composite was approximately 95-fold and 19-fold higher than that of NU66 and ZnO samples,respectively.The enhanced activity of the 5%wt NU66/ZnO nanocomposite was further confirmed through photoelectrochemical analysis.The formation of type II heterojunctions between the counterparts significantly suppressed recombination of the photogenerated charge carriers.Photocatalytic degradation experiments with different quenchers indicated that the effect of superoxide anion radicals(•O_(2)^(−))had a greater effect than the other scavengers.Additionally,the improved photocatalytic mechanism underlying the activity of NU66/ZnO nanocomposites was also explored.These findings establish a basis for development of MOF based heterojunction for photocatalytic organic pollution remediation.展开更多
Nutrient limitation in agriculture is a big problem in many tropical areas. Much research has focused on the optimal use of crop residues in agriculture. Recent work indicates that plant residue decomposition rates, i...Nutrient limitation in agriculture is a big problem in many tropical areas. Much research has focused on the optimal use of crop residues in agriculture. Recent work indicates that plant residue decomposition rates, including nutrient release rates can be increased by pre-exposure to sunlight. This has potential as a technology to manipulate nutrient release from residues to match crop demands. The possible development and use of this technology is discussed. There is some evidence that this could increase emissions of trace gases, but the increase is thought to be small. Research needs are discussed.展开更多
Melanin, the main photoreceptor in living organics, is largely abundant in pigmented hair tissues. Its promising properties have been widely studied in order to fully explore the corresponding applications. However, t...Melanin, the main photoreceptor in living organics, is largely abundant in pigmented hair tissues. Its promising properties have been widely studied in order to fully explore the corresponding applications. However, the photodegradating and aggregating natures of melanin, to some extent, restrict the development of this eco-friendly biomaterial. This study is conducted to overcome both disadvantages by a mature method that coating the original melanin nanoparticles with silica as shells. The results revealed that the aggregation of the melanin/silica nanoparticles (MSNP) was decreased obviously by a 5 h coating and appeared a uniformly mono-dispersed solution. The MSNP that coated for 20 h provided an efficient protection on the photodegradation of the melanin with a 50% maintenance of the melanin content compared with 16% of original melanin and 2% of MSNP-5 h.展开更多
Photodegradation has emerged as an environmentally friendly method of decomposing harmful dyes in wastewater. In this study, core-shell Fe3O4/SiO2/ TiO2 nanospheres with magnetic cores were obtained from synthesised m...Photodegradation has emerged as an environmentally friendly method of decomposing harmful dyes in wastewater. In this study, core-shell Fe3O4/SiO2/ TiO2 nanospheres with magnetic cores were obtained from synthesised magnetic Fe3O4 nanoparticles through the precipitation method, the surface of the magnetic Fe3O4 nanoparticles was coated with a silica (SiO2) layer by hydrolysis of tetramethoxysilane (TMOS) as a silica source, and finally, Fe3O4/SiO2 nanospheres were coated with titanium (TiO2) layer using tetrabutyltitanate (TBT) as a precursor through the sol-gel process. The morphology and structure of the prepared materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDAX), Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM). The photocatalytic activities of the prepared core-shell nanospheres were studied using binary azo dyes, namely methyl orange (anionic dye, MO) and methylene blue (cationic dye, MB) in aqueous solution under UV light irradiation (365 nm), and UV-Vis spectrophotometer was utilised to monitor the amount of each dye in the mixture. It was found that 90.2% and 100% of binary MO and MB were removed for 5 h, respectively. The results revealed that the efficiency of the photocatalytic degradation of the core-shell nanospheres was not degreased after five runs that can be used as recyclable photocatalysts. The results show that the performance of the prepared core-shell nanospheres was better than that of commercial TiO2 nanoparticles. Moreover, the magnetic separation properties of the core-shell Fe3O4/SiO2/TiO2 nanospheres can enable the prepared materials to have wider application prospects.展开更多
Toxicity in reaction mixtures of atrazine irradiated on immobilized TiO2 at varying irradiation times was studied using an algal growth test on unicellular green alga Raphidocelis subcapitata and a cytotoxicity test w...Toxicity in reaction mixtures of atrazine irradiated on immobilized TiO2 at varying irradiation times was studied using an algal growth test on unicellular green alga Raphidocelis subcapitata and a cytotoxicity test with a RTgill-W1 cell line. The toxicity of atrazine samples to algae decreased exponentially with the time of irradiation on TiO2 up to 3 h for both IC50 and IC20 values calculated for growth rate inhibition and yield. A trend to increasing variability between replicates in atrazine samples irradiated on TiO2 for longer time periods was observed;the trend was particularly pronounced in samples irradiated for 3 and 5 hours, where the atrazine samples caused moderate stimulation in lower concentration treatments (up to 550 μg/l of the initial atrazine concentration). None of the atrazine samples showed significant cytotoxicity to the rainbow trout gill cell line (RTgill-W1).展开更多
The effects of UV-irradiation on stability of pure and blended polystyrene films with phthalate and terephthalate plasticizers were studied in presence of air. UV-visible, fluorescence and FT-IR techniques were used t...The effects of UV-irradiation on stability of pure and blended polystyrene films with phthalate and terephthalate plasticizers were studied in presence of air. UV-visible, fluorescence and FT-IR techniques were used to study the photodegradation of irradiated polystyrene films. Increase of irradiation times of polystyrene films caused an increase in the intensity of the main absorption band and the increase in the intensity of a new absorption band at longer wavelength, thus indicating a possibility of photo degradation of polystyrene chains. The influence of added plasticizers, dimethyl terephthalate, diethyl terephthalate, dioctyl terephthalate, dioctylphthalate, and dibutyl phthalate on photo-quenching of the polymer fluorescence band was also investigated, and found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of excimer and monomer fluorescence bands maxima was also found to decrease with a small red shift with the increase in irradiation times. These changes may be attributed to the formation of new photo-products resulted from the photodegradation of irradiated polymeric chains. The photo- quenching rate constant was found to increase with the increase of the molar mass and bulkiness of the used plasticizers and to increase with the increase in irradiation time. The rate constant of the photo quenching process was found to decrease with the increase in the percent of added plasticizers, indicating that the added plasticizers might act as UV-absorbers which inhibited the photodegradation process. The analysis of the FT-IR spectra of the irradiated and nonirradiated samples showed a noticeable formation of new broad band centered at 1727 cm-1, and its intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added plasticizer. In addition, the observed increase in the intensities of the carbonyl and hydroxyl absorption regions of the FT-IR spectra provided evidence for the photodegradation as well as photo-oxidation of polymeric chains.展开更多
The photodegradation of thin films of poly (4-chlorostyrene) and poly (4-bromostyrene) with 265 nm radiation in the presence of oxygen and as a function of irradiation time has been studied mainly using fluorescence, ...The photodegradation of thin films of poly (4-chlorostyrene) and poly (4-bromostyrene) with 265 nm radiation in the presence of oxygen and as a function of irradiation time has been studied mainly using fluorescence, FT-IR, and UV-VIS spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Phthalate and terephthalate-plasticizers were found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of absorption was also found to increase with irradiation time and in the intensity of a new absorption band at longer wavelength. The appearance of new fluorescence bands in the irradiated polymer films can well indicate a possibility of photodegradation of polymer films. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, providing evidence for the photodegradation as well as the photo-oxidation of polymeric chains. The increase in the analyzed ranges was attributed to the formation of alcohols, aliphatic ketones and to the increase in the number of (C=C) that resulted from hydrogen abstraction during chains - scission.展开更多
Atorvastatin, widely prescribed hypolipidemic drug, undergoes rapid, probably self-sensitised, degradation (less than 20% left after 25-minute irradiation) if irradiated by wavelengths 300 - 350 nm in aqueous solution...Atorvastatin, widely prescribed hypolipidemic drug, undergoes rapid, probably self-sensitised, degradation (less than 20% left after 25-minute irradiation) if irradiated by wavelengths 300 - 350 nm in aqueous solution. When ferric ions are added to the reaction mixture, the degradation follows first order kinetics with a rate constant of 0.130 min<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>. Photochemical degradation may thus represent a significant way of environmental transformation of this pharmaceutical. Toxicity testing of atorvastatin and atorvastatin photoproducts performed on the water plant <em>Lemna minor</em> revealed that atorvastatin itself exhibited no observable toxic effect measured as leaf area growth inhibition, while the photoproducts showed a significant toxicity to the plant, which shows the extreme importance of investigating not only toxicity of drugs themselves on aquatic organisms but also effects of their transformation products.展开更多
La,Ce co-doped ZnO nanorods(ZnLC)were synthesized through a one-step solvothermal route.The photocatalysts were characterized by X-ray diffraction,Raman spectroscopy,field-emission scanning electron microscopy,energy ...La,Ce co-doped ZnO nanorods(ZnLC)were synthesized through a one-step solvothermal route.The photocatalysts were characterized by X-ray diffraction,Raman spectroscopy,field-emission scanning electron microscopy,energy dispersive X-ray,transmission electron microscopy,UV-vis diffuse reflectance spectroscopy and photo luminescence spectroscopy.The La and Ce doping enhanced the visible light absorption ability of ZnLC and a red shift was detected for ZnLC.Under simulated solar light irradiation,the ZnO doped with 3 at%La and 1 at%Ce(ZnLC1)degrades methylene blue(MB)more effectively than those of pure ZnO,La-doped ZnO(ZnL)and commercially available ZnO.The improved photocatalytic performance of ZnLC1 can be attributed to the high charge separation efficiency as demonstrated by the photoluminescence spectra.Additionally,the photocatalytic experiments reveal that several parameters have their own impact on the MB degradation.Using a variety of radical scavengers,it is discovered that superoxide anion radical plays a crucial role in the degradation of MB.The ZnLC1 is also reused several times without noticeable decrease of photoactivity,indicating that it has a substantial potential for environmental remediation applications.展开更多
Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health ...Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.展开更多
The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry.Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs,...The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry.Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs,2-hydroxyfluorene(2-OHFL)and 9-hydroxyfluorene(9-OHFL),which are newly recognized contaminants in the wider environment including colder regions.Interestingly,their photodegradation kinetics were clearly influenced by whether they reside in ice or water.Under the same simulated solar irradiation(λ>290 nm),OHFLs photodegraded faster in ice than in equivalent aqueous solutions and this was attributed to the specific concentration effect caused by freezing.Furthermore,the presence of dissolved constituents in ice also influenced photodegradation with 2-OHFL phototransforming the fastest in‘seawater’ice(k=(11.4±1.0)×10^(−2) min^(−1))followed by‘pure-water’ice((8.7±0.4)×10^(−2) min^(−1))and‘freshwater’ice((8.0±0.7)×10^(−2) min^(−1)).The presence of dissolved constituents(specifically Cl^(−),NO_(3)^(−),Fe(Ⅲ)and humic acid)influences the phototransformation kinetics,either enhancing or suppressing phototransformation,but this is based on the quantity of the constituent present in the matrixes,the specific OHFL isomer and the matrix type(e.g.,ice or aqueous solution).Careful derivation of key photointermediates was undertaken in both ice and water samples using tandem mass spectrometry.Ice phototransformation exhibited fewer by-products and‘simpler’pathways giving rise to a range of hydroxylated fluorenes and hydroxylated fluorenones in ice.These results are of importance when considering the fate of PAHs and OH-PAHs in cold regions and their persistence in sunlit ice.展开更多
Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation...Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozoneassisted catalytic oxidation(OZCO) and photocatalytic oxidation(PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary,we propose the challenges of VUV photodegradation and perspectives for its future development.展开更多
基金Ho Chi Minh City University of Technology (HCMUT),VNU-HCM for supporting this study。
文摘In this study,three-dimensional porous magnesium ferrite/titanium dioxide/reduced graphene oxide(Mg Fe_2O_(4)-GM/TiO_(2)/rGO(MGTG))was successfully synthesized via green and hydrothermal-supported co-precipitation methods using the extract of Garcinia mangostana(G.mangostana)as a reducing agent.The characterization results indicate the successful formation of the nano/micro Mg Fe_(2)O_(4)(MFO)and TiO_(2) on the structure of the reduced graphene oxide(rGO),which can also act as efficient support,alleviating the agglomeration of the nano/micro MFO and TiO_(2).The synergic effects of the adsorption and photodegradation activity of the material were investigated according to the removal of crystal violet(CV)under ultraviolet light.The effects of catalyst dosage,CV concentration,and p H on the CV removal efficiency of the MGTG were also investigated.According to the results,the CV photodegradation of the MGTG-200 corresponded to the pseudo-first-order kinetic model.The reusability of the material after 10 cycles also showed a removal efficiency of 92%.This happened because the materials can easily be recollected using external magnets.In addition,according to the effects of different free radicals·O_(2)^(-),h^(+),and·OH on the photodegradation process,the photocatalysis mechanism of the MGTG was also thoroughly suggested.The antibacterial efficiency of the MGTG was also evaluated according to the inhibition of the Gram-positive bacteria strain Staphylococcus aureus(S.aureus).Concurrently,the antibacterial mechanism of the fabricated material was also proposed.These results confirm that the prepared material can be potentially employed in a wide range of applications,including wastewater treatment and antibacterial activity.
文摘Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein the impurity level observed around 0.1% well below the threshold 0.5%. The approach to identify anonymous species was adopted as first to generate the impurity in sample, isolate, enrich and was subjected to LC-MS/MS and NMR for spectral studies. Based on the spectral data the anonymous species were identified as a “Lumibudesonide’’ ((5aR,5bS,5cS,6S,7aS,7bS,10aR,11aS,11bS)-6-hydroxy-7b-(2-hydroxyacetyl)-5b,7a-dimethyl-9-propyl 1,5a,5b,5c,6,7,7a,7b,10a,11,11a,11b dodecahydrocyclopenta[2'',3'']cyclopropa [1'',2'':3', 4']benzo [1',2':4,5]indeno [1,2-d][1,3]dioxol-5(2H)-one), which is observed in photolysis of Budesonide.
文摘The emerging contaminants(ECs)are organic compounds including pharmaceuticals.These products are consumed in large quantities,favoring their continuous entrance to the environment and affecting the health of living beings.Diclofenac is a non-steroidal anti-inflammatory drug with analgesic properties of prolonged release.It is the commonest postoperative analgesic,and it is highly consumed without prescription.In recent years,the capability of microalgae to remove pharmaceuticals in water has been tested as a promising tool.In this work,the removal efficiency of diclofenac(16µg/mL)by the microalga Nannochloropsis oculata CCAP 186/7 was evaluated.The major nutrient concentrations in Bold’s Basal Medium were modified(nitrogen and carbon:50 and 100%of their original concentration)to know their effect in the removal of diclofenac.Drug degradation by light was also evaluated.The maximum removal capacity of diclofenac in the medium was 68.8%.The percentage of diclofenac adsorbed on the cell wall was between 6 and 12.7%.Around 23.6%of diclofenac was degraded by light after 18 days.N.oculata did not show growth inhibition due to the presence of diclofenac.The results obtained point to the promissory application of N.oculata as a bioremediation system for diclofenac removal.
基金Sponsored by the Key Project of National Science Foundation of China (Grant NO.50638020)the National High Technology Research and Development Program of China (Grant No.2007AA06A411)the State Key Laboratory of Urban Water Resource & Environment (Grant No.2009TS04)
文摘The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the photodegradation behaviors of EE2 in the UV/H2O2 process.The results indicated that the addition of coexisting substances can influence the photodegradation behaviors of EE2 and it also follows the first-order kinetics.The acidic (pH 2-4) and alkaline (pH 10-12) medium benefit the photodegradation of EE2,but the photodegradation rate constant of EE2 keeps almost constant in the pH value of 4-10.The addition of anions,such as HCO3-,Cl-and NO3-,can inhibit the photodegradation of EE2,and the rate constant has a negative linear relationship with the concentration of the anions.However,the reduction degrees vary with the anions kinds,and the inhibition effect of the three anions is in the order of HCO3->NO3->Cl-.Addition of 5 mg/L methanol and bisphenol A can reduce the photodegradation rate constant of EE2by 84.31% and 72%,respectively.By comparison,the retardant effect of methanol is much more evident.In the studied concentrations range,the photodegradation rate constant of EE2 is the unary quadratic function of the organic compounds concentrations.
文摘The photodegradation of irradiated thin films of poly (para-methylstyrene) with 265 nm radiations in the presence of airand as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR Spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on stability of poly (para-methylstyrene) towards irradiations was also investigated. Blending with phthalate plasticizers was found to cause a higher efficiency of photodegradation than that obtained in doping with terephthalate plasticizers. The intensity of absorption was also found to increase with time of irradiation and in change in the shape of the spectra at longer wavelength, thus indicating a possibility of photodegradation of polymer chains. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, shows a predominant absorption associated with carbonyl compounds with 1740 cm-1. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, have provided an evidence for the photodegradation as well as photo-oxidation of polymeric chains. The presence of the plasticizer in the polymer backbone was found to accelerate the photodegradation of polymeric chains.
基金supported by the National Natural Science Foundation of China(Nos.40976041 and 20775074)
文摘The relationship between chemical structures and photodegradation activity of 12 PAHs is studied using DFT and HF methods, and stepwise multiple linear regression analysis method. The equilibrium geometries and vibration frequency have been investigated by considering Solvent effects using a selfconsistent reaction field based on the polarizable continuum model. With DFT and HF methods, different quantum chemical structural descriptors are obtained by quantum chemical calculation and the results with DFT method are better for QSAR model. It is concluded that the photodegradation activity is closely related to its molecular structure. In the regression analysis, the main factors affecting photodegradation rate include the energy of the highest occupied orbital EHOMO and the number of six-carbon benzene ring N1, and the QSAR model successfully established is logkb = 6.046 + 54.830EHOMO + 0.272N1. Statistical evaluation of the developed QSAR shows that the relationships are statistically significant and the model has good predictive ability. EHOMO is the most important factor influcing the photodegradation of PAHs, because the higher EHOMO is, the more easily electron will be excited and the more easily molecular will be degraded. Comparison of the photodegradation of PAHs with their biodegradation shows that the committed step of biodegradation is that the effects of microorganisms make the chemical bond break, while in the committed step of photodegradation PAHs eject electrons.
文摘The biodegradation behavior in vitro and in vivo of polycaprolactone-poly (ethylene glycol) block copolymer (PCE) was reported in detail. In this paper, photodegradation test of PCE was performed by exposure to UV light The mechanical properties and the inherent viscosity of PCE samples which are subjected to photodegradation were determined. The experimental results indicated that poly (ethylene glycol) (PEO) segment in PCE copolymer is photosensitive. The photodegra-dation rate of the PCE was increased with increasing poly (ethylene glycol) content.
文摘Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants.These two models were designated for(1)contaminants with high photolytic rates or high photolytic quantum yields,whose photodegradation is unlikely to be enhanced by aquatic photosensitisers;and(2)contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis.The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples,simulated solar experiments in the laboratory,and transfer of the laboratory results to realise water treatment using the prediction models.Although similar models have been widely used for laboratory studies,this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters.
基金the Zhoushan Science and Technology Project(2020C21023)Zhoushan Free Trade Zone International Cooperation(2019010301)Putu District of Zhoushan Environmental Special Supporting Project(PT2020e001).
文摘Semiconductor photocatalysis is a novel highly efficient and low-cost method for removing organic pollutants from wastewater.However,the photoreduction performance of semiconductors on organic pollutants is limited due to the weak absorption of visible light caused by its wide band gap and low carrier utilization rate resulting from severe electron-holes recombination.In the present study,flower-like NH_(2)-UiO-66(NU66)/ZnO nanocomposites were prepared using a facile method and exhibited high efficiency under visible light driven photocatalysts.The X-ray diffractometer(XRD),scanning electron microscope(SEM),transmitor electron microscope(TEM),and X-ray photoelectron spectroscopy(XPS)were used to characterize the prepared samples,indicating that NU66/ZnO was successfully synthesized.The photocatalytic activity of the prepared NU66/ZnO nanocomposites was determined by measuring the photodegradation of methylene blue(MB)and malachite green(MG)under visible-light irradiation.The optimal nanocomposite loading of 5%wt NU66 to NU66/ZnO demonstrated the highest photocatalytic activity for the degradation of MB.The photocatalytic activity of a 5%NU66/ZnO composite was approximately 95-fold and 19-fold higher than that of NU66 and ZnO samples,respectively.The enhanced activity of the 5%wt NU66/ZnO nanocomposite was further confirmed through photoelectrochemical analysis.The formation of type II heterojunctions between the counterparts significantly suppressed recombination of the photogenerated charge carriers.Photocatalytic degradation experiments with different quenchers indicated that the effect of superoxide anion radicals(•O_(2)^(−))had a greater effect than the other scavengers.Additionally,the improved photocatalytic mechanism underlying the activity of NU66/ZnO nanocomposites was also explored.These findings establish a basis for development of MOF based heterojunction for photocatalytic organic pollution remediation.
文摘Nutrient limitation in agriculture is a big problem in many tropical areas. Much research has focused on the optimal use of crop residues in agriculture. Recent work indicates that plant residue decomposition rates, including nutrient release rates can be increased by pre-exposure to sunlight. This has potential as a technology to manipulate nutrient release from residues to match crop demands. The possible development and use of this technology is discussed. There is some evidence that this could increase emissions of trace gases, but the increase is thought to be small. Research needs are discussed.
文摘Melanin, the main photoreceptor in living organics, is largely abundant in pigmented hair tissues. Its promising properties have been widely studied in order to fully explore the corresponding applications. However, the photodegradating and aggregating natures of melanin, to some extent, restrict the development of this eco-friendly biomaterial. This study is conducted to overcome both disadvantages by a mature method that coating the original melanin nanoparticles with silica as shells. The results revealed that the aggregation of the melanin/silica nanoparticles (MSNP) was decreased obviously by a 5 h coating and appeared a uniformly mono-dispersed solution. The MSNP that coated for 20 h provided an efficient protection on the photodegradation of the melanin with a 50% maintenance of the melanin content compared with 16% of original melanin and 2% of MSNP-5 h.
文摘Photodegradation has emerged as an environmentally friendly method of decomposing harmful dyes in wastewater. In this study, core-shell Fe3O4/SiO2/ TiO2 nanospheres with magnetic cores were obtained from synthesised magnetic Fe3O4 nanoparticles through the precipitation method, the surface of the magnetic Fe3O4 nanoparticles was coated with a silica (SiO2) layer by hydrolysis of tetramethoxysilane (TMOS) as a silica source, and finally, Fe3O4/SiO2 nanospheres were coated with titanium (TiO2) layer using tetrabutyltitanate (TBT) as a precursor through the sol-gel process. The morphology and structure of the prepared materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDAX), Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM). The photocatalytic activities of the prepared core-shell nanospheres were studied using binary azo dyes, namely methyl orange (anionic dye, MO) and methylene blue (cationic dye, MB) in aqueous solution under UV light irradiation (365 nm), and UV-Vis spectrophotometer was utilised to monitor the amount of each dye in the mixture. It was found that 90.2% and 100% of binary MO and MB were removed for 5 h, respectively. The results revealed that the efficiency of the photocatalytic degradation of the core-shell nanospheres was not degreased after five runs that can be used as recyclable photocatalysts. The results show that the performance of the prepared core-shell nanospheres was better than that of commercial TiO2 nanoparticles. Moreover, the magnetic separation properties of the core-shell Fe3O4/SiO2/TiO2 nanospheres can enable the prepared materials to have wider application prospects.
文摘Toxicity in reaction mixtures of atrazine irradiated on immobilized TiO2 at varying irradiation times was studied using an algal growth test on unicellular green alga Raphidocelis subcapitata and a cytotoxicity test with a RTgill-W1 cell line. The toxicity of atrazine samples to algae decreased exponentially with the time of irradiation on TiO2 up to 3 h for both IC50 and IC20 values calculated for growth rate inhibition and yield. A trend to increasing variability between replicates in atrazine samples irradiated on TiO2 for longer time periods was observed;the trend was particularly pronounced in samples irradiated for 3 and 5 hours, where the atrazine samples caused moderate stimulation in lower concentration treatments (up to 550 μg/l of the initial atrazine concentration). None of the atrazine samples showed significant cytotoxicity to the rainbow trout gill cell line (RTgill-W1).
文摘The effects of UV-irradiation on stability of pure and blended polystyrene films with phthalate and terephthalate plasticizers were studied in presence of air. UV-visible, fluorescence and FT-IR techniques were used to study the photodegradation of irradiated polystyrene films. Increase of irradiation times of polystyrene films caused an increase in the intensity of the main absorption band and the increase in the intensity of a new absorption band at longer wavelength, thus indicating a possibility of photo degradation of polystyrene chains. The influence of added plasticizers, dimethyl terephthalate, diethyl terephthalate, dioctyl terephthalate, dioctylphthalate, and dibutyl phthalate on photo-quenching of the polymer fluorescence band was also investigated, and found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of excimer and monomer fluorescence bands maxima was also found to decrease with a small red shift with the increase in irradiation times. These changes may be attributed to the formation of new photo-products resulted from the photodegradation of irradiated polymeric chains. The photo- quenching rate constant was found to increase with the increase of the molar mass and bulkiness of the used plasticizers and to increase with the increase in irradiation time. The rate constant of the photo quenching process was found to decrease with the increase in the percent of added plasticizers, indicating that the added plasticizers might act as UV-absorbers which inhibited the photodegradation process. The analysis of the FT-IR spectra of the irradiated and nonirradiated samples showed a noticeable formation of new broad band centered at 1727 cm-1, and its intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added plasticizer. In addition, the observed increase in the intensities of the carbonyl and hydroxyl absorption regions of the FT-IR spectra provided evidence for the photodegradation as well as photo-oxidation of polymeric chains.
文摘The photodegradation of thin films of poly (4-chlorostyrene) and poly (4-bromostyrene) with 265 nm radiation in the presence of oxygen and as a function of irradiation time has been studied mainly using fluorescence, FT-IR, and UV-VIS spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Phthalate and terephthalate-plasticizers were found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of absorption was also found to increase with irradiation time and in the intensity of a new absorption band at longer wavelength. The appearance of new fluorescence bands in the irradiated polymer films can well indicate a possibility of photodegradation of polymer films. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, providing evidence for the photodegradation as well as the photo-oxidation of polymeric chains. The increase in the analyzed ranges was attributed to the formation of alcohols, aliphatic ketones and to the increase in the number of (C=C) that resulted from hydrogen abstraction during chains - scission.
文摘Atorvastatin, widely prescribed hypolipidemic drug, undergoes rapid, probably self-sensitised, degradation (less than 20% left after 25-minute irradiation) if irradiated by wavelengths 300 - 350 nm in aqueous solution. When ferric ions are added to the reaction mixture, the degradation follows first order kinetics with a rate constant of 0.130 min<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>. Photochemical degradation may thus represent a significant way of environmental transformation of this pharmaceutical. Toxicity testing of atorvastatin and atorvastatin photoproducts performed on the water plant <em>Lemna minor</em> revealed that atorvastatin itself exhibited no observable toxic effect measured as leaf area growth inhibition, while the photoproducts showed a significant toxicity to the plant, which shows the extreme importance of investigating not only toxicity of drugs themselves on aquatic organisms but also effects of their transformation products.
文摘La,Ce co-doped ZnO nanorods(ZnLC)were synthesized through a one-step solvothermal route.The photocatalysts were characterized by X-ray diffraction,Raman spectroscopy,field-emission scanning electron microscopy,energy dispersive X-ray,transmission electron microscopy,UV-vis diffuse reflectance spectroscopy and photo luminescence spectroscopy.The La and Ce doping enhanced the visible light absorption ability of ZnLC and a red shift was detected for ZnLC.Under simulated solar light irradiation,the ZnO doped with 3 at%La and 1 at%Ce(ZnLC1)degrades methylene blue(MB)more effectively than those of pure ZnO,La-doped ZnO(ZnL)and commercially available ZnO.The improved photocatalytic performance of ZnLC1 can be attributed to the high charge separation efficiency as demonstrated by the photoluminescence spectra.Additionally,the photocatalytic experiments reveal that several parameters have their own impact on the MB degradation.Using a variety of radical scavengers,it is discovered that superoxide anion radical plays a crucial role in the degradation of MB.The ZnLC1 is also reused several times without noticeable decrease of photoactivity,indicating that it has a substantial potential for environmental remediation applications.
基金supported by the National Natural Science Foundation of China (Nos.42177354 and 21777032)the National Key R&D Program of China (No.2019YFC0214402)the Guangdong Basic and Applied Basic Research oundation (No.2019B151502064)。
文摘Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.
基金supported by the National Natural Science Foundation of China (Nos. 21976045, 22076112)the CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation (No. 2020KFJJ03)+2 种基金the State Environmental Protection Key Laboratory of Coastal Ecosystem (No. 202102)the China Scholarship Council (CSC) Scholarship (Nos. 201704180014, 201704180009)the Chinese Arctic and Antarctic Administration
文摘The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry.Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs,2-hydroxyfluorene(2-OHFL)and 9-hydroxyfluorene(9-OHFL),which are newly recognized contaminants in the wider environment including colder regions.Interestingly,their photodegradation kinetics were clearly influenced by whether they reside in ice or water.Under the same simulated solar irradiation(λ>290 nm),OHFLs photodegraded faster in ice than in equivalent aqueous solutions and this was attributed to the specific concentration effect caused by freezing.Furthermore,the presence of dissolved constituents in ice also influenced photodegradation with 2-OHFL phototransforming the fastest in‘seawater’ice(k=(11.4±1.0)×10^(−2) min^(−1))followed by‘pure-water’ice((8.7±0.4)×10^(−2) min^(−1))and‘freshwater’ice((8.0±0.7)×10^(−2) min^(−1)).The presence of dissolved constituents(specifically Cl^(−),NO_(3)^(−),Fe(Ⅲ)and humic acid)influences the phototransformation kinetics,either enhancing or suppressing phototransformation,but this is based on the quantity of the constituent present in the matrixes,the specific OHFL isomer and the matrix type(e.g.,ice or aqueous solution).Careful derivation of key photointermediates was undertaken in both ice and water samples using tandem mass spectrometry.Ice phototransformation exhibited fewer by-products and‘simpler’pathways giving rise to a range of hydroxylated fluorenes and hydroxylated fluorenones in ice.These results are of importance when considering the fate of PAHs and OH-PAHs in cold regions and their persistence in sunlit ice.
文摘Volatile organic compounds(VOCs) have attracted much attention for decades as they are the precursors of photochemical smog and are harmful to the environment and human health. Vacuum ultraviolet(VUV) photodegradation is a simple and effective method to decompose VOCs (ranging from tens to hundreds of ppmV) without additional oxidants or catalysts in the air at atmospheric pressure. In this paper, we review the research progress of VOCs removal via VUV photodegradation. The fundamentals are outlined and the key operation factors for VOCs degradation, such as humidity, oxygen content, VOCs initial concentration, light intensity, and flow rate, are discussed. VUV photodegradation of VOCs mixture is elucidated. The application of VUV photodegradation in combination with ozoneassisted catalytic oxidation(OZCO) and photocatalytic oxidation(PCO) systems, and as the pre-treatment technique for biological purification are illustrated. Based on the summary,we propose the challenges of VUV photodegradation and perspectives for its future development.
