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1.
A. V. Vorontsov D. V. Kozlov P. G. Smirniotis V. N. Parmon 《Kinetics and Catalysis》2005,46(3):422-436
The results of studies on the TiO2 photocatalytic oxidation of model air pollutants are summarized. The kinetics of photocatalytic oxidation of CO and the vapors of a number of simple organic substances was studied in detail. It was found that, in the course of reaction, all of the test substances underwent complete mineralization. Gaseous substrates were converted with the participation of several types of reaction centers. The photocatalytic oxidation of sulfur- and phosphorus-containing substances resulted in gradual deactivation of the photocatalyst; however, its activity can be restored by washing the photocatalyst with water. It was found that, along with oxidation, the steps of hydrolysis play an important role in the photocatalytic degradation of air pollutants, such as dimethyl methylphosphonate and 2-chloroethyl sulfide.__________Translated from Kinetika i Kataliz, Vol. 46, No. 3, 2005, pp. 450–465.Original Russian Text Copyright © 2005 by Vorontsov, Kozlov, Smirniotis, Parmon. 相似文献
2.
Highly photoactive bi-phase nanocrystalline TiO2 photocatalyst was prepared by a solvent evaporation-induced crystallization (SEIC) method, and calcined at different temperatures.
The obtained TiO2 photocatalyst was characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas.
The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results show that solvent
evaporation can promote the crystallization and phase transformation of TiO2 at 100°C. When calcination temperatures are below 600°C, the prepared TiO2 powders show bimodal pore size distributions in the mesoporous region. At 700°C, the pore size distributions exhibit monomodal
distribution of the inter-aggregated pores due to the collapse of the intra-aggregated pores. At 100°C, the obtained TiO2 photocatalyst by this method shows good photocatalytic activity, and at 400°C, its photocatalytic activity exceeds that of
Degussa P25. This may be attributed to the fact that the prepared TiO2 photocatalyst has higher specific surface areas, smaller crystallite size and bimodal pore size distribution. 相似文献
3.
J. A. León-Ramos D. Kibanova P. Santiago-Jacinto Y. Mar-Santiago M. Trejo-Valdez 《Journal of Sol-Gel Science and Technology》2011,57(1):43-50
Crystalline anatase phase TiO2 with photocatalytic properties was obtained through a sol–gel low-temperature hydrothermal process. TiO2 samples doped with tungsten oxide were also obtained by using this synthetic approach. The photocatalytic oxidation of methylene
blue in water was monitored to study the influence of the tungsten doping degree on the photocatalytic degradation performance
of TiO2. The degradation rate constant was further increased by adjusting the tungsten doping degree of hydrothermal TiO2. Also, a much faster photodegradation of methylene blue was achieved using tungsten doped samples baked at 450°C. The results
were compared with those obtained with Degussa P25 used as photocatalyst. The structure and optical properties of tungsten-doped
TiO2 were studied by SEM, X-ray diffraction, UV–vis and DRIFT spectroscopy techniques. 相似文献
4.
The photocatalytic activity of TiO2 nanofibers immobilized on quartz substrates was investigated by evaluating the decomposition of organic pollutants. TiO2 nanofibers were synthesized by electrospinning the Ti-precursor/polymer mixture solution, followed by hot-pressing for enhancing
the adhesion of TiO2-nanofiber films to the substrates. TiO2 started to crystalize in the anatase form at 500 °C and reached the optimal photocatalytic anatase/rutile phase ratio of
70:30 at a calcination temperature of 600 °C. The TiO2-nanofiber film was demonstrated to be an efficient photocatalyst by ranitidine decomposition under UV illumination and was
proven to have a comparable photocatalytic activity with the well-known Degussa P25 nanoparticulate photocatalyst and excellent
recyclability during 10 cycles of photocatalytic operation, indicating no loss of TiO2 nanofibers during photocatalytic operations. 相似文献
5.
Hiroshi Taoda 《Research on Chemical Intermediates》2008,34(4):417-426
Recently, environmental disruption is proceeding on a global scale through the consumption of huge amounts of fossil fuels
and the emission of various chemical substances. However, these substances resist bio-treatment. TiO2 generates electrons and holes by irradiation with light. Most organic micro-pollutants, including dioxins, are decomposed
into carbon dioxide and water by the effect of the holes with high oxidative potential. By using such a photocatalytic reaction,
various applications are feasible for environmental cleanup. In general, TiO2 powder has been utilized as photocatalyst, although TiO2 powder photocatalyst has several disadvantages: (1) it is difficult to handle, (2) photocatalytic reaction is slow and it
takes a lot of time for treatment and (3) it is difficult to apply to plastics and textiles, because the photocatalyst decomposes
them. We have developed a photocatalyst suitable for practical use and have developed high-activity photocatalysts such as
TiO2 photocatalytic transparent film, photocatalytic silica-gel, apatite-coated TiO2 photocatalyst usable for plastics and textiles, photocatalytic paper, photocatalytic blue charcoal and photocatalytic oxygen
scavenger. The application of these high-activity photocatalysts has been studied in deodorization, anti-bacterial, self-cleaning,
anti-stain, water treatment, air purification such as photocatalytic decomposition of dioxins and VOC, and NO
x
removal. Now various photocatalytic articles using these new photocatalyst materials are on the market in Japan. Photocatalytic
technology can create many valuable products for environmental use all over the world. 相似文献
6.
C.-L. Zhang S.-J. Cui Y. Wang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(11):2306-2311
The photocatalytic degradation of pefloxacin was studied using modified TiO2 as a photocatalyst. The effect of various parameters such as the amount of the photocatalyst, the initial concentration of pefloxacin, initial pH value on the process were investigated, and the optimal conditions were determined. The optimal amount of the photocatalyst is 0.3 g/L. The photodegradation rate of pefloxacin decreases with the increase of initial concentration. Alkaline medium is favorable for the photocatalytic degradation process. The primary photo-degradation products were analyzed by HPLC-ESI-MS/MS and thus the process mechanism was discussed. 相似文献
7.
Jingfei Luan Hongling Cai Xiping Hao Jibiao Zhang Guoyou Luan Xiaoshan Wu Zhigang Zou 《Research on Chemical Intermediates》2007,33(6):487-500
Bi2FeVO7 was prepared by a solid-state reaction technique for the first time and the structural and photocatalytic properties of Bi2FeVO7 were studied. The results shows that this compound crystallized in the tetragonal crystal system with space group I4/mmm.
Moreover, the band gap of Bi2FeVO7 was estimated to be about 2.22(6) eV. For the photocatalytic water splitting reaction, H2 or O2 evolution was observed from pure water with Bi2FeVO7 as the photocatalyst by ultraviolet light irradiation. Degradation of aqueous methylene blue (MB) dye by photocatalytic way
over this compound was further studied under visible light irradiation. Bi2FeVO7 shows higher catalytic activity compared to TiO2 (P-25) for MB photocatalytic degradation under visible light irradiation. Complete removal of aqueous MB was realized after
visible light irradiation for 170 min with Bi2FeVO7 as the photocatalyst. The reduction of the total organic carbon (TOC) and the formation of inorganic products, SO
4
2−
and NO
3
−
revealed the continuous mineralization of aqueous MB during the photocatalytic course. 相似文献
8.
Paruchai Pongwan Khatcharin Wetchakun Sukon Phanichphant Natda Wetchakun 《Research on Chemical Intermediates》2016,42(4):2815-2830
Bare TiO2 and Cu-doped TiO2 nanoparticles with different nominal doping amounts of Cu ranging from of 0.5 to 5.0 mol% were synthesized using the modified sol–gel method. The samples were physically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller-specific surface area, UV–Vis diffuse reflectance spectroscopy, zeta potential, X-ray photoelectron spectroscopy, inductively coupled plasma, and photoluminescence techniques. The Cu-doped TiO2 exhibited good photocatalytic activity in mineralization of oxalic acid and formic acid under visible light irradiation. Photomineralization of oxalic and formic acids under visible light irradiation revealed greatly enhanced photoactivity exhibited by the 2.0 mol% Cu-doped TiO2 photocatalyst compared to bare TiO2 . The enhanced photocatalytic performance arises from copper ion doping in the TiO2 structure, leading to an extended photoresponsive range, enhanced photogenerated charge separation, and transportation efficiency. 相似文献
9.
In this work, a nitrogen-doped anatase TiO2 nanocrystal is prepared by a modified sol-gel preparation method using the nonionic surfactant (polyoxyethylene sorbitan monooleate) as a structural controller and a soft template. The as-prepared samples are characterized by X-ray diffraction, Raman spectroscopy, UVVis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy techniques. Then the photocatalytic activity of these samples is assessed by the photocatalytic oxidation of phenol under visible light irradiation. The phenol concentration is measured using a UV-Vis spectrometer. Experimental results show that N-doping leads to an excellent visible light photocatalytic activity of the TiO2 nanocatalyst. Furthermore, the formation energy and electronic structure of pure and N-doped anatase TiO2 are described by density functional theory (DFT) calculations. It is found that N-doping narrowed the band gap of bare TiO2, which leads to an excellent visible light photocatalytic activity of N–TiO2 nanocatalysts. Therefore, the prepared N–TiO2 photocatalyst is expected to find the use in organic pollutant degradation under solar light illumination. 相似文献
10.
Radina Kralchevska Maria Milanova Petya Kovacheva Jovo Kolev Georgi Avdeev Dimitar Todorovsky 《Central European Journal of Chemistry》2011,9(6):1027-1038
Microcomposites consisting of TiO2 (or Ce-doped TiO2) and ThO2 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of ThO2. X-ray diffraction study reveals the effects of ThO2 (compared to the ThO2-free TiO2, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The photocatalytic
tests in presence of the composites under UV irradiation reveal an increase of the Malachite Green degradation rate constant.
The effect depends on the Th relative content, temperature of annealing of the catalyst and addition of other doping agent.
The highest photocatalytic activity is observed for TiO2 obtained at 550°C and containing 1% ThO2. The composite exhibits activity in dark, also. The presence of Ce4+ ions is not an obligatory requirement for the realization of the ThO2 effect. The reported results suggest that the radioactivity of the Th and/or its decay products is one of the main factors
responsible for the increased photocatalytic activity of TiO2.
相似文献
11.
This review focuses on the heterogeneous photocatalytic treatment of organic dyes in air and water. Representative studies spanning approximately three decades are included in this review. These studies have mostly used titanium dioxide (TiO2) as the inorganic semiconductor photocatalyst of choice for decolorizing and decomposing the organic dye to mineralized products. Other semiconductors such as ZnO, CdS, WO3, and Fe2O3 have also been used, albeit to a much smaller extent. The topics covered include historical aspects, dark adsorption of the dye on the semiconductor surface and its role in the subsequent photoreaction, semiconductor preparation details, photoreactor configurations, photooxidation kinetics/mechanisms and comparison with other Advanced Oxidation Processes (e.g., UV/H2O2, ozonation, UV/O3, Fenton and photo-Fenton reactions), visible light-induced dye decomposition by sensitization mechanism, reaction intermediates and toxicity issues, and real-world process scenarios. 相似文献
12.
Wonyong Choi 《Catalysis Surveys from Asia》2006,10(1):16-28
Semiconductor photocatalysis is a process that harnesses light energy in chemical conversions. In particular, its applications to environmental remediation have been intensively investigated. The characteristics of TiO2, the most popular photocatalyst, is briefly described and selected studies on the degradation/conversion of various recalcitrant pollutants using pure and modified TiO2 photocatalysts, which were carried out in this group, are reviewed. Photocatalytic reactions are multi-phasic and take place at interfaces of not only water/TiO2 and air/TiO2 but also solid/TiO2. Examples of photocatalytic reactions of various organic and inorganic substrates that are converted through the photocatalytic oxidation or reduction are introduced. TiO2 has been modified in various ways to improve its photocatalytic activity. Surface modifications of TiO2 that include surface platinization, surface fluorination, and surface charge alteration are discussed and their applications to pollutants degradation are also described in detail. 相似文献
13.
Dong-liang Ji Jianzhong Zhu Min Ji Yang Leng 《Research on Chemical Intermediates》2016,42(6):5413-5429
Nano-TiO2 is frequently used as an optimal photocatalyst, since it is nontoxic, low cost, and environmentally friendly, especially for its photocatalytic oxidation action. However, its photocatalytic reducing action has not been widely researched. In this study, TiO2 doped with different concentrations of manganese was prepared by the sol–gel method and characterized using different techniques to analyze the surface structure, phase composition, and surface elements of the different materials. To investigate the photocatalytic activity, Mn–TiO2 was used for photocatalytic reduction of Cr(VI). Moreover, various organic pollutants were added to determine whether they enhanced the photocatalytic reduction of Cr(VI). The experiments indicated that the presence of Mn in TiO2 could enhance its photocatalytic reduction action, especially at 0.02 % molar ratio. Manganese ions doped in TiO2 behaved as electron accumulation sites. In addition, pH value, and photocatalyst dosage were investigated to analyze their effects on the photocatalytic reduction action. The results show that lower pH value improved the efficiency of photocatalytic reduction; there were no significant changes in the photocatalytic reduction rate with dosage above 1.0 g/L. In the presence of different electron donors (organic pollutants as hole scavengers), the photocatalytic reduction of Cr(VI) was generally improved. In short, manganese-doped TiO2 exhibited improved photocatalytic reduction activity, especially in cooperation with various organics. 相似文献
14.
Horst Böttcher Boris Mahltig Jamal Sarsour Thomas Stegmaier 《Journal of Sol-Gel Science and Technology》2010,55(2):177-185
The preparation of TiO2-coated polyester fabrics for purposes of photocatalytic water purification requires coating agents with crystalline TiO2 particles preferably in the anatase modification. The resulting coatings should exhibit a high water resistance and high
photocatalytic activity according to reaction with structurally different dyestuffs. For this, the synthesis of anatase sols
by hydrolysis of tetraisopropyltitanate in acidic medium under reflux was optimized. By precoating or addition of polymeric
epoxysilanes a good adhesion on the polyester support could be realized. The photocatalytic activity was tested with different
dyestuffs as: Methylene blue, Rhodamine B and the azo dyes AcidOrange 7 and C.I. Reactive red 158. The rate of photodestruction
depends strongly on the type of used dye and its structure. Surprisingly, no differences in photodegradation were found in
case of investigations with Rhodamine B, if the photoreaction is performed under exposure with UV or with visible light. A
possible explanation of the similar behavior of photoreaction under different light sources could be a photodestruction by
electron transfer from Rhodamine B to TiO2. Therefore, Rhodamine B seems to be generally not suitable for the evaluation of the photoactivity of TiO2 under irradiation with visible light. 相似文献
15.
Shuhua Yao Yaxing Zhang Zhongliang Shi Shaofeng Wang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(1):69-73
A series of nano-titania (TiO2) photocatalytic materials with a hollow fiber structure were successfully prepared using tetra-n-butyl titanate (Ti(OC4H9)4) as precursor and cotton fiber as the template. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and N2 adsorption-desorption measurements were employed to characterize the morphology, crystal structure, and surface structure of the samples. The photocatalytic activities of the samples were studied by phenol photodegradation in water under UV irradiation. The effect of calcination temperature, photocatalyst dosage, initial concentration of phenol and irradiation time on the photodegradation of phenol was studied. Results showed that the TiO2 fiber materials have hollow structures, indicating that these materials had a large specific surface area. The fiber structure material showed better photocatalytic properties for the degradation of phenol than pure TiO2 under UV light, and the sample calcined at 500°C exhibited the highest phenol photodegradation efficiency. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed, the photocatalytic activity of TiO2 fiber remained ca. 90% of photocatalytic activity of the fresh sample after being used four times. Moreover, TiO2 fiber was easily recovered by centrifugal separation from water. 相似文献
16.
Ming-Yue Ding De-Shui Meng Yan-Hong Tang Cheng-Bin Liu Sheng-Lian Luo 《Chemical Papers》2015,69(11):1411-1420
One-dimensional (1D) Ag/AgBr/TiO2 nanofibres (NFs) have been successfully fabricated by the one-pot electrospinning method. In comparison with bare TiO2 NFs and Ag/AgBr/PVP (polyvinylpyrrolidone) NFs, the 1D Ag/AgBr/TiO2 NFs photocatalyst exhibits much higher photocatalytic activity in the degradation of a commonly used dye, methylene blue (MB), under visible light. The photocatalytic removal efficiency of MB over Ag/AgBr/TiO2 NFs achieves almost 100 % in 20 min. The photocatalytic reaction follows the first-order kinetics and the rate constant (k) for the degradation of MB by Ag/AgBr/TiO2 NFs is 5.2 times and 6.6 times that of Ag/AgBr/PVP NFs and TiO2 NFs, respectively. The enhanced photocatalytic activity is ascribed to the stronger visible light absorption, more effective separation of photogenerated electron-hole pairs, and faster charge transfer in the long nanofibrous structure. The Ag/AgBr/TiO2 NFs maintain a highly stable photocatalytic activity due to its good structural stability and the self-stability system of Ag/AgBr. The mechanisms for photocatalysis associated with Ag/AgBr/TiO2 NFs are proposed. The degradation of MB in the presence of scavengers reveals that h+ and ?O 2 ? significantly contribute to the degradation of MB. 相似文献
17.
Nan Wang Yaozhuo Xu Lihua Zhu Xiantao Shen Heqing Tang 《Journal of photochemistry and photobiology. A, Chemistry》2009,201(2-3):121-127
Photocatalytic reduction/oxidation and deactivation of TiO2 photocatalyst was investigated in the systems composed of Cr(VI) and salicylic acid. The selection of analysis method of Cr(IV) was very important to the monitoring of the photocatalytic process. It was found that as previously reported, serious deactivation of TiO2 catalyst in the simultaneous photo-reduction of Cr(VI) and oxidation of salicylic acid was incorrectly observed if the Cr(VI) level was analyzed by directly monitoring the absorbance at characteristic 348 nm band of Cr(VI), because it seriously suffers from the interferences of the intermediates generated from the degradation of salicylic acid. By using an appropriate method to determine the Cr(VI) concentration, it was observed that all the added Cr(VI) could be reduced, not showing marked deactivation of the photocatalyst. A long time photocatalytic reduction of Cr(VI) under UV illumination induced the deposition of Cr(III) species on the surface of TiO2 particles, which could cause a mild deactivation of the photocatalyst. However, the accompanied oxidation of salicylic acid was demonstrated to depress the deactivation effect of the deposited Cr(III) species on the photocatalytic activity of the TiO2 photocatalyst. 相似文献
18.
Jenia Georgieva 《Journal of Solid State Electrochemistry》2012,16(3):1111-1119
The application of electrochemically enhanced photocatalysis in air treatment using a Nafion-based photoelectrochemical cell
and TiO2/WO3 photoanodes for organic vapor photooxidation under both UV and visible light irradiation is briefly presented. In that direction,
the obtained results regarding the preparation and characterization of the TiO2/WO3 photoanodes with enhanced photocatalytic activity are reviewed. Particular emphasis is given in the comparison of the photocatalytic
behavior of bilayer TiO2/WO3 coatings, electrosynthesized on stainless steel mesh and powder C + mixed (WO3 + TiO2) photoanodes. The advantages of using a high surface area C + mixed (WO3 + TiO2) powder catalysts as photoanodes against their plain TiO2 + C and WO3 + C analogues are discussed. 相似文献
19.
A. V. Vorontsov E. A. Kozlova A. S. Besov D. V. Kozlov S. A. Kiselev A. S. Safatov 《Kinetics and Catalysis》2010,51(6):801-808
The results of many-year studies of the relationship between the physical properties and photocatalytic activity of TiO2 and Pt/TiO2 in photocatalytic purification and disinfection of air and water and water photodecomposition with oxygen evolution are presented.
Recommendations are given as to finding the optimal method for platinum supporting on TiO2 to achieve the highest possible catalytic activity. Multisite kinetic models of the gas-phase oxidation of simple organic
substances are considered. Methods for regenerating the photocatalyst after its deactivation in the oxidation of sulfur-containing
organic substances are suggested. New data are discussed on the acceleration of air purification by the combination of photocatalytic
oxidation with atmospheric electric discharges, the addition of gaseous hydrogen peroxide, and oxidation on photocatalysts
existing in the aerosol state. As compared to pure TiO2, platinated titanium dioxide has a higher capability for disinfection and complete mineralization of microorganisms. Two
promising methods for production of hydrogen from water using solar light are presented. 相似文献
20.
Hongliang Xu Shiping Sun Sanying Jiang Hailong Wang Rui Zhang Qinfu Liu 《Journal of Sol-Gel Science and Technology》2018,87(3):676-684
Kaolinite/TiO2 composites were prepared by using sol-gel method and raw kaolin, pretreated kaolinite and tetrabutyl titanate as the main raw materials. X-ray diffractometer, field-emission scanning electron microscope and infrared spectrometer analysis were carried out to characterize the phase composition and microstructure of the samples. The photocatalytic performance of the kaolinite/TiO2 composites were evaluated by degrading the methylene blue (MB) and phenol aqueous solution, respectively. The results show that intercalation and exfoliation reduced the size and thickness of kaolinite particles. Acid treatment improved the distribution and the loading quantity of TiO2 grains. When the kaolinite/TiO2 composites were calcined at 500?°C, the tetragonal structure of anatase particles of 30–100?nm in size were obtained, but the exfoliated kaolinite crystals were damaged. The degradation rate of MB increased gradually with the extension of photocatalytic reaction time and the enhancement of photocatalyst dosage. The adsorption performance of acid-treated kaolinite/TiO2 composite (AKT) was nearly the same as that of raw kaolin/TiO2 composite (RKT), but that of the exfoliated kaolinite/TiO2 composite (EKT) was the most excellent. The photocatalytic performance of AKT and EKT were better than that of RKT, and AKT exhibited the optimum property. Under a certain photocatalyst dosage and photocatalysis time, the absorption rate and the degradation rate decreased gradually with the enhancement of initial concentration of MB. Similar result was also acquired for the degradation of phenol. Both the acid treating and the exfoliating to kaolinite enhanced the photocatalytic performance of the kaolinite/TiO2 composite photocatalysts, but acid treatment may be more helpful to the preparation of high performance kaolinite/TiO2 composite photocatalyst. 相似文献