共查询到20条相似文献,搜索用时 15 毫秒
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Satyen Gautam Sanjay P Kamble Sudhir B Sawant Vishwas G Pangarkar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(3):359-364
The photocatalytic degradation of 3‐nitrobenzenesulfonic acid in the presence of solar radiation and artificial UV radiation with suspended TiO2 was studied in a batch and continuous annular reactor, respectively. The effects of catalyst loading, pH, presence of anions and cations and initial concentration on the rate of photocatalytic degradation were investigated. Concentration–time data were correlated with the rate equation d[Ct=0]/dt = krK[Ct=0]/(1 + K[Ct=0]). Studies were carried out to compare the photolytic, photochemical and photocatalytic methods of degradation. Copyright © 2005 Society of Chemical Industry 相似文献
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Hana Žabová Vladimír Církva 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(11):1624-1630
BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO2 in the form of thin films containing transition metal ions Mn+ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO2, and H2O, and decomposition of Rhodamine B on the thin films were investigated in detail. RESULTS: Polycrystalline thin doped TiO2 films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO2 films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO2 film, the UV/Vis spectra of V, Zr and Ag‐doped TiO2 showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min?1), which was higher than that on the pure TiO2 film by a factor of 1.7, was obtained with the Ag(3%)/TiO2 photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO2 was determined. CONCLUSIONS: Transition metal ion‐doped TiO2 thin films showed significant absorption in the visible region. The metal doped TiO2 photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry 相似文献
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Engineered TiO2 and SiO2‐TiO2 films on silica‐coated glass for increased thin film durability under abrasive conditions 下载免费PDF全文
Rosa Elena Ramírez‐García Jesús Alberto González‐Rodríguez Miguel Arroyo‐Ortega Sergio Alfonso Pérez‐García Liliana Licea‐Jiménez 《International Journal of Applied Ceramic Technology》2017,14(1):39-49
Thin films durability is critical to retain its performance in real life applications. For automotive glass, further factors such as haze appearance developed under abrasive conditions become relevant to ensure the driver's visibility. Macroscopic abrasion resistance tests of TiO2/SiO2 and SiO2–TiO2/SiO2 thin films on soda‐lime silica (SLS) glass were performed according to an American standard for safety grazing. The purpose of this, was to increase the top active film durability in a bilayer system by understanding how film thickness and top film composition influence abrasion performance. In order to achieve this understanding, three approaches were considered: (a) determination of the influence of TiO2 top film thickness, (b) replacement of the TiO2 top film by SiO2–TiO2 films, and (c) determination of the influence of SiO2–TiO2 film thickness. Results showed that thinner top TiO2 film thickness leads to SiO2/TiO2 bilayers with lower haze value and improved abrasion resistance. It was also found that SiO2 addition to TiO2 top film composition promotes the thin film adhesion and sample durability against abrasive wear. Friction coefficient and micro‐hardness measurements support the abrasion results. Factors contributing to the improvement of the lifetime performance of TiO2 and SiO2–TiO2 thin films were identified. 相似文献
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Characteristics of photocatalytic oxidation of gaseous 2‐propanol using thin‐film TiO2 photocatalyst
Chiu‐Ping Chang Jong‐Nan Chen Ming‐Chun Lu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(11):1293-1300
This work presents a photocatalysis‐based method to treat and purify air because of its broad applicability to common, oxidizable, air contaminants. The effect of oxygen content, temperature, water vapor, and 2‐propanol concentration on the TiO2 surface was investigated. The rate of 2‐propanol decomposition increased with increasing the oxygen content, but was reduced at temperatures higher than 100°C. When water vapor concentration was in the range of 10–355 mmol m?3, the rate of 2‐propanol decomposition was proportional to the water content. However, an opposite result was observed at a higher concentration of water vapor. 2‐Propanol was photooxidized to acetone, and eventually to carbon dioxide and water. The kinetic model of 2‐propanol photooxidation was successfully developed by the competitive Langmuir–Hinshelwood rate form, incorporating the inhibition effect coming from the formation of acetone. Copyright © 2004 Society of Chemical Industry 相似文献
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Poly(L ‐lactic acid)‐titanium dioxide nanocomposites (with various loadings of TiO2: 0.5, 1, 2, 5, and 10 wt %) were produced by solution casting method. The influence of TiO2 on thermal properties and crystallinity of PLA was investigated by DSC and FTIR spectroscopy. The TiO2 nano filler has no significant influence on the characteristic temperatures (Tg, Tc, and Tm), but has high impact on the crystallinity of these systems. The degree of crystallinity Xc significantly increases for PLA nanocomposites loaded with up to 5 wt % of TiO2, while for 10 wt % load of TiO2 it drops below Xc of the pure resin. The degradation of the prepared composites was evaluated hydrolytically in 1N NaOH, enzymatically in α‐amylase solutions, and under UV irradiation. The catalytic effect of TiO2 nano particles on the degradation processes under UV light exposure (λ = 365 nm) and hydrolytic degradation was confirmed with the increase of the filler content. The opposite effect was identified in enzymatic degradation experiments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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G. E. Imoberdorf G. Vella A. Sclafani L. Rizzuti O. M. Alfano A. E. Cassano 《American Institute of Chemical Engineers》2010,56(4):1030-1044
The radiation field of a packed‐bed photocatalytic reactor filled with quartz wool coated with titanium dioxide was modeled using the Monte Carlo technique and the following information: the radiation flux emitted by the lamps, the diameter size distribution of the quartz fiber cloth, the mass of quartz fibers and of TiO2 that was immobilized on the fiber surface as well as the refractive index, and the spectral absorption coefficient of the materials of the system. Modeling predictions were validated with radiometer measurements of the transmitted radiation through the reactor, the root mean square error being <9.7%. Finally, by means of a parametric study, the validated model was used to analyze the effect of the design variables, such as the radii of the quartz fibers, thickness of the TiO2 coatings, and amount of TiO2‐coated quartz wool, on the distribution and nonuniformity of the radiative energy distribution inside the reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2010 相似文献
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Vu Duc Chinh Le Xuan Hung Luca Di Palma Vu Thi Hong Hanh Giorgio Vilardi 《化学工程与技术》2019,42(2):308-315
A carbon nanotube (CNT)/gold nanoparticle (NP) nanocomposite was synthesized by simultaneously reducing the Au ions and depositing Au NPs on the surface of a CNT. The functional groups were investigated with Fourier transform infrared spectra. From the Raman spectra, the D‐band and G‐band of the CNT were identified. The deposition of nanometer‐sized Au NPs on the CNT sites was observed by transmission electron microscopy. The photodegradation of methylene blue (MB) in aqueous solutions was studied using various photocatalysts, including TiO2, TiO2‐SiO2, CNT/TiO2, CNT/TiO2‐SiO2, Au/TiO2, CNT‐Au/TiO2, and CNT‐Au/TiO2‐SiO2 composites. CNT addition leads to a synergic effect, improving the photoactivity of the catalysts. A possible physically based mechanism was proposed involving the reduction of electron‐hole recombination and fast electron‐transfer possibility. 相似文献
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KambalaV Subba Rao Basavaraju Srinivas Pierre Boule Machiraju Subrahmanyam 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(5):568-575
Regioselective photooxidative demethylation of methyl‐substituted N‐containing heterocyclic compounds is investigated in non‐aqueous (ethane nitrile) solutions containing semiconductor oxide (TiO2) as photocatalyst in the presence of molecular oxygen upon irradiation at room temperature conditions. A plausible electron transfer mechanism, in which an electron‐hole pair is generated on the surface of TiO2 by illumination, is proposed for the semiconductor‐mediated photocatalysis. Molecular orbital calculation by the AM 1 method has been performed for the electron densities of N‐atoms of heterocyclics in the present study. © 2002 Society of Chemical Industry 相似文献
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A new associating system has been elaborated from mixing a degradable polymer, poly(β‐malic acid‐co‐β‐ethyladamantyl malate), and a β‐cyclodextrin polymer in aqueous solution. Viscosity and dynamic light scattering measurements have been made on solutions of the single copolyester and of mixtures of both polymers. Studies on copolyesters with different percentages of hydrophobic groups (0–7.5%) show that a small proportion of the chains (less than 5% in weight) are aggregated in large structures (100 nm) which dominate the scattering intensity. The mixtures exhibit slow diffusive relaxation modes which correlate with a large viscosity enhancement at low concentration. These effects, which depend sensitively on pH, are attributed to the presence of polydisperse complexes of copolyester and β‐cyclodextrin polymer. The influence of pH, ionic strength, medium composition, and concentration were examined on the mixture of copolymers. It was found that the association properties are controlled by the net charge on the amphiphilic copolyester. © 2001 Society of Chemical Industry 相似文献
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Jun Wang Ronghe Li Zhaohong Zhang Xiangdong Zhang Wei Sun Hao Wang Rui Xu Zhiqiang Xing 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(6):588-597
A phase transformation of micron‐sized TiO2 powder from anatase to rutile was attempted by heat‐treatment in order to generate a new mixed crystal TiO2 with high associated photocatalytic activity. Heat‐treated micron‐sized TiO2 powders at different transition stages were characterized by X‐ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT‐IR) and transmission electron microscopy (TEM) methods. The tests of photocatalytic activity of the heat‐treated micron‐sized TiO2 powders were conducted by the photocatalytic degradation of Rhodamine B and Acid Red B under visible light irradiation. The results indicate that mixed crystal TiO2 photocatalyst heat‐treated at 400 °C for 60 min shows the highest photocatalytic activity. It can effectively decompose the Rhodamine B and Acid Red B in aqueous solution after 6 h visible light irradiation. A remarkable improvement in photocatalytic activity of TiO2 is caused by the formation of combined rutile–anatase phases and separation of photogenerated electron–hole pairs. Copyright © 2007 Society of Chemical Industry 相似文献
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Jing Wang Guangfei Liu Hong Lu Ruofei Jin Jiti Zhou 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):970-974
BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor (AILR) in combination with the TiO2‐photocatalytic ozonation (TiO2/UV/O3) process was investigated for the degradaton of 1‐amino‐ 4‐bromoanthraquinone‐2‐ sulfonic acid (ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon (GAC) as biocarrier, could run steadily for 4 months at 1000 mg L?1 of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand (COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO2/UV/O3 process more significantly improved the mineralization rate of ABAS bio‐decolorization products with over 90% TOC removal efficiency, compared with O3, TiO2/UV and UV/O3 processes. Furthermore, the release efficiencies of Br? and SO42? could reach 84.5% and 80.2% during TiO2/UV/O3 treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO2/UV/O3 was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry 相似文献
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Jordi Palau Josep M. Penya‐Roja Carmen Gabaldón Francisco Javier Álvarez‐Hornos Feliu Sempere Vicente Martínez‐Soria 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(2):273-281
BACKGROUND: One of the most important industrial sources of volatile organic compounds (VOCs) is related to coating and painting applications. In this sense, photocatalytic oxidation can become an innovative and promising alternative for the remediation of air polluted by VOCs. In this study the UV photodegradation of m‐xylene, toluene and n‐butyl acetate, as representative compounds of paint solvents, was carried out in an annular reactor using a TiO2–glass wool supported catalyst. RESULTS The removal of each component and their mixture, simulating an industrial emission, was evaluated under different operational conditions. A maximum elimination capacity of 12, 18 and 80 mg C m?3 s?1 was reached for m‐xylene, toluene and n‐butyl acetate, respectively. A simple Langmuir–Hinshelwood kinetic model was used to match the experimental data. Photocatalytic oxidation was found to be more effective for all compounds when humidified air was used. CONCLUSIONS: No mass transfer limitation was found under the experimental conditions. n‐butyl acetate was the easiest to degrade and m‐xylene the most recalcitrant. In the abatement of the mixture, competitive adsorption between the pollutants was observed, with the degradation of toluene especially hindered. A nearly linear correlation was found between the UV light intensity and kinetic constants. Copyright © 2010 Society of Chemical Industry 相似文献
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A new type of photodegradable poly(vinyl chloride)‐bismuth oxyiodide/TiO2 (PVC‐BiOI/TiO2) nanocomposite film was prepared by embedding a nano‐TiO2 photocatalyst modified by BiOI into the commercial PVC plastic. The solid‐phase photocatalytic degradation behavior of the as‐prepared film was investigated in ambient air at room temperature under UV light irradiation, with the aid of UV‐Vis spectroscopy, weight loss monitoring, scanning electron microscopy, and FT‐IR spectroscopy. Compared to the PVC‐TiO2 nanocomposite film, the PVC‐BiOI nanocomposite film and the pure PVC film, the PVC‐BiOI/TiO2 nanocomposite film exhibited a higher photocatalytic degradation activity. The optimal mass ratio of BiOI to TiO2 was found to be 0.75 %. The weight loss rate of the PVC‐BiOI/TiO2 nanocomposite film reached 30.8 % after 336 h of irradiation, which is 1.5 times higher than that of the PVC‐TiO2 nanocomposite film under identical conditions. The solid‐phase photocatalytic degradation mechanism of the nanocomposite films was briefly discussed. 相似文献
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Weifeng Cao Benkun Qi Juan Zhao Changsheng Qiao Yi Su Yinhua Wan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):808-817
BACKGROUND: β‐poly(malic acid) (PMLA) can be used as a pro‐drug or for a drug‐delivery system. Effects of pH, dissolved oxygen concentration (DO) and stirring speed were investigated to improve PMLA production by A. pullulans ipe‐1. RESULTS: The strain produced a high PMLA concentration when pH and DO remained at about 6.0 and above 70%, respectively, and the yeast‐like cells were the main PMLA producers. To further promote PMLA production, the cultivation could be divided into three phases. In phase I, cell growth was accelerated by maintaining high DO (>70%) with a constant stirring speed of 800 rpm. In phase II, PMLA production was increased by controlling DO at 70% using the automatically controlled stirring speed. In phase III, PMLA production on per gram of glucose (Yp/s) was enhanced by keeping DO at 70%, and using a low stirring speed to decrease cell growth. Compared with batch cultures, a higher PMLA yield was obtained with this strategy, i.e. PMLA production and Yp/s increased by 15% and 18%, respectively. CONCLUSION: Control strategies for pH, DO and stirring speed provide a good reference for process development and optimization of PMLA production. © 2012 Society of Chemical Industry 相似文献