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11.
Takashi Yamamoto Atsushi Ohara Yukio Noma Katsushi Nishizawa Akio Yasuhara Shin-ichi Sakai 《Journal of Material Cycles and Waste Management》2007,9(2):188-193
The photodegradation of tetraphenyltin (TePT) contained in polychlorinated biphenyl (PCB)-based transformer oil simulants
by ultraviolet (UV) irradiation in alkaline 2-propanol solutions was examined. In the absence of PCBs, the TePT level fell
to below 1% of the initial concentration within 30 min. In the absence of both PCBs and an alkali, the concentrations of tri-,
di-, and monophenyltins initially increased to a few milligrams per liter, and then reduced to below the detection limits
within 90 min. The addition of an alkali to the reaction solution slightly accelerated the photodecomposition of TePT. The
decomposition of other phenyltins (PTs) was also accelerated. When PCBs with concentrations of approximately 80 times the
initial TePT concentration were added, only a small fraction of the TePT decomposed within 100 min. Moreover, the levels of
PTs did not change during irradiation. TePT and other PTs did decompose when the level of PCBs was reduced to the same concentration
as that of TePT; however, the decomposition rates were slower than those in the absence of PCBs. In the actual treatment process,
TePT and other PTs in PCB-based transformer oil are decomposed by catalytic reduction, which is used after UV irradiation.
Therefore, in the actual treatment of PCB-based transformer oil wastes, pollution due to PTs can be prevented. 相似文献
12.
ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 Å and c= 10.014323 Å. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min-1 for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO42- and NO3-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography- mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. 相似文献
13.
M. Brigante M. DellaGreca L. Previtera M. Rubino F. Temussi 《Environmental Chemistry Letters》2005,2(4):195-198
The photolytic decomposition of hydrochlorothiazide in water was investigated. Irradiation of the drug was performed in pure water and sewage treatment plant water with a solar simulator and by direct sunlight. Here we show that three photoproducts were obtained. Two of them were formed in yields much higher than 10%. An environmental risk assessment of hydrochlorothiazide should take into account also these photoproducts in a complete analytical and ecotoxicological evaluation. 相似文献
14.
M. I. Silva H. D. Burrows S. J. Formosinho L. Alves A. Godinho M. J. Antunes D. Ferreira 《Environmental Chemistry Letters》2007,5(3):143-149
Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this
study, the lowest excited state (3MLCT) of Ru(bpy)32+ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light
and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted
chlorophenols has been followed in the presence of Ru(bpy)32+/S2O82− with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques.
Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl−, H+ and SO42− ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant
organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic
process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first
order behaviour. Further studies on this were made by following Cl− release with respect to the initial Ru(bpy)32+ and S2O82− concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied
at acidic and alkaline pH. 相似文献
15.
The aerobic visible-light-photosensitised irradiation of methanolic solutions of either of the phenolic-type contaminants model compounds (ArOH) p-phenylphenol (PP), p-nitrophenol (NP) and phenol (Ph), and for two additional phenolic derivatives, namely p-chlorophenol (ClP) and p-methoxyphenol (MeOP), used in some experiments, was carried out. Employing the natural pigment riboflavin (Rf) as a sensitiser, the degradation of both the ArOH and the very sensitiser was observed. A complex mechanism, common for all the ArOH studied, operates. It involves superoxide radical anion (O2√−) and singlet molecular oxygen (O2(1Δg)) reactions. Maintaining Rf in sensitising concentrations levels (≈0.02 mM), the mechanism is highly dependent on the concentration of the ArOH. Kinetic experiments of oxygen and substrate consumption, static fluorescence, laser flash photolysis and time-resolved phosophorescence detection of O2(1Δg) demonstrate that at ArOH concentrations in the order of 10 mM, no chemical transformation occurs due to the complete quenching of Rf singlet excited state. When ArOH is present in concentrations in the order of mM or lower, O2√− is generated from the corresponding Rf radical anion, which is produced by electron transfer reaction from the ArOH to triplet excited Rf. The determined reaction rate constants for this step show a fairly good correlation with the electron-donor capabilities for Ph, PP, NP, ClP and MeOP. In this context, the main oxidative species is O2√−, since O2(1Δg) is quenched in an exclusive physical fashion by the ArOH. The production of O2√− regenerates Rf impeding the total degradation of the sensitiser. This kinetic scheme could partially model the fate of ArOH in aquatic media containing natural photosensitisers, under environmental conditions. 相似文献
16.
The photooxidation of dye solutions containing Fe(III)-citrate complexes was studied. The photodegradation under near-UV light of the five dyes, C. I. reactive red 2, C. I. reactive blue 4, C. I. reactive black 8, C. I. basic red 13 and C. I. basic yellow 2, in aqueous solutions at pH2.0 containing Fe(III)-citrate complexes was found to follow pseudo-first order kinetics. The photodegradation rates of the dye, C. I. reactive red 2, decreased with increasing the initial dye concentration in range of 20 – 60 mg/L . A comparatively higher photodegradation efficiency of the dye was gained under the condition of pH2.0 and the Fe(III) to citrate ratio 1:2. 相似文献
17.
Mouheb Sboui Mohamed Faouzi Nsi Ali Rayes Meenakshisundaram Swaminathan Ammar Houas 《环境科学学报(英文版)》2017,29(10):3-13
A novel photocatalyst based on TiO_2–PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline(PANI)–modified TiO_2 on cork. The TiO_2–PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction(XRD),scanning electron micrograph(SEM), transmission electron microscopy(TEM), thermogravimetric analysis(TGA), Fourier transform infrared spectroscopy(FT-IR), UV–vis diffuse reflectance spectra(UV–vis DRS) and the Brunauer–Emmett–Teller(BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO_2–PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency. 相似文献
18.
Chenchen Li Lijie Yan Yiming Li Dan Zhang Mutai Bao Limei Dong 《Frontiers of Environmental Science & Engineering》2021,15(4):72
19.
Combined UV-biological degradation of PAHs 总被引:6,自引:0,他引:6
The UV-photolysis of PAHs was tested in silicone oil and tetradecane. In most cases, the degradation of a pollutant provided within a mixture was lower than when provided alone due to competitive effects. With the exception of anthracene, the larger pollutants (4- and 5-rings) were always degraded first, proving that UV-treatment preferentially acts on large PAHs and thereby provides a good complement to microbial degradation. UV-photolysis was also found to be suitable for treatment of soil extract from contaminated soils. The feasibility of UV-biological treatment was demonstrated for the removal of a mixture of phenanthrene and pyrene in silicone oil. UV-irradiation of the silicone oil led to 83% pyrene removal but no phenanthrene photodegradation. Subsequent treatment of the oil in a two-phases partitioning bioreactor (TPPB) system inoculated with Pseudomonas sp. was followed by complete phenanthrene biodegradation but no further pyrene removal. Totally, the combined process allowed 92% removal of the PAH mixture. Further work should focus on characterizing the photoproducts formed and studying the influence of the solvent on the photodegradation process. 相似文献
20.
Can Shen Xiangping Gu Bin Yang Dexian Zhang Zhilin Wang Zhengxiang Shu Jeffrey Dick Anhuai Lu 《环境科学学报(英文版)》2020,32(3):156-166
Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes. To develop value in the exploitation of sphalerite, samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions. The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight, Mn from 0.004% to 4.868%, Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%. As Fe became more abundant, the color of natural sphalerite darkened, becoming almost black; and higher Fe content was associated with stronger visible light absorption. Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content. Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity. Specifically, the degradation of Methyl Orange (30 mg/L) attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with 4.262% Fe and 1.576% Cd. Overall, the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes, while substitution by Cd was observed to have a greater effect on the photocatalytic properties. These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite. 相似文献