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Preparation and properties of a new composite photocatalyst based on nanosized titanium dioxide 总被引:1,自引:0,他引:1
The use of photocatalysts supported on adsorbents is receiving substantial attention. Supporting TiO2 with zeolites is found to be one of the best solutions to increase the efficiency of TiO2-based photocatalysts. This work was focused on simple preparation of a TiO2/Na-ZSM-5 composite catalyst by the solid state dispersion (SSD) method and its modification with an organic photosensitizer
— polythiophene (PT). Using the XRD diffractometry, structure of the new composite catalyst was proved. Beside this composite
catalyst, mechanical mixtures of TiO2-based catalysts with Na-ZSM-5 zeolite were prepared. The efficiency of all five available photocatalysts (TiO2, TiO2-PT, mechanical mixture of TiO2 + Na-ZSM-5, mechanical mixture of TiO2-PT + Na-ZSM-5, and the modified SSD-PT composite) on photodegradation of 4-chlorophenol was compared. By measuring the formation
of chloride ions and decreasing the 4-chlorophenol concentration at two different initial concentrations of 4-chlorophenol
in the basic aqueous solution, the photoefficiency and adsorption properties of our photocatalysts were determined.
Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May
2008. 相似文献
3.
V. A. Matveev V. I. Zakharov D. B. Mayorov T. V. Kondratenko 《Russian Journal of Inorganic Chemistry》2011,56(3):338-340
The properties of silicon dioxide precipitates produced by acid processing of nepheline have been investigated. Regardless of the production method, silicon dioxide takes an intermediate position between commercial silica gel and white soot in terms of the structure and some physicochemical properties, this position determining possible applications of this product. 相似文献
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Khalameida S. Sydorchuk V. Levytska S. Shcherban N. 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2131-2142
Journal of Thermal Analysis and Calorimetry - The samples containing 1–10% tin dioxide supported onto silica gel have been synthesized via precipitation or thermolysis of tin tetrachloride.... 相似文献
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S. T. Cheng C. R. Chenthamarakshan N. R. de Tacconi K. Rajeshwar 《Research on Chemical Intermediates》2007,33(3-5):225-237
Chemical treatment followed by thermal annealing of titanium dioxide nanoparticle film surfaces with urea or ammonium acetate were found to exert a profound influence on their photoelectrochemical or photocatalytic activity. These films were dip-coated over conducting substrates, then dipped in urea or ammonium acetate aqueo us solutions, and finally baked at 300 or 500°C to yield two sets of chemically-treated TiO2 (CT-TiO2) films. The incident photon to electron conversion efficiency (IPCE) of the CT-TiO2 films in the near-UV region was significantly higher compared to the pristine (untreated) TiO2 samples baked similarly at 300 or 500°C. Higher photocurrents for formate photo-oxidation were also observed for the CT-TiO2 samples relative to their untreated TiO2 counterparts. All the CT-TiO2 films showed better photocatalytic activity toward Cr(VI) reduction with respect to their untreated TiO2 counterparts. The enhanced performance of the CT-TiO2 films was attributed to morphological changes as seen in scanning electron microscopy images. Possible reasons for the performance improvement in terms of better charge carrier separation properties of the CT-TiO2 films are finally discussed. 相似文献
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D. A. Zherebtsov A. M. Kolmogortsev V. V. Viktorov V. V. D’yachuk D. M. Galimov A. S. Serikov G. G. Mikhailov 《Russian Journal of Inorganic Chemistry》2010,55(12):1850-1856
Mesoporous TiO2 has been obtained by template synthesis. The introduction of a surfactant in the hydrolysis of tetrabutoxytitanium in aqueous ethanol allows the structure of the resulting material to be controlled. The amorphous TiO2 resulting from hydrolysis turns into anatase on being calcined at 300°C. As determined by X-ray diffraction, the anatase crystallite size is 70 nm in the presence of the highest surfactant concentration examined and 210 nm in the absence of a surfactant. Amorphous materials have been characterized by electron microscopy and differential thermal analysis. The ultimate benzene adsorption value has been determined for calcined mesoporous TiO2. 相似文献
7.
A. N. Murashkevich O. A. Alisienok I. M. Zharskii E. V. Korobko N. A. Zhuravskii Z. A. Novikova 《Colloid Journal》2014,76(4):465-470
The properties of electrorheological fluids containing dispersed phase of titanium dioxide nanoparticles prepared via the sol-gel method and modified with metal oxides have been studied. Titanium dioxide has the anatase structure with crystallite sizes of 8–10 nm and a specific surface area of 90–140 m2/g. It has been found that the magnitude of the electrorheological response of the filler is determined by the specific surface area and the content of a modifying component. The strongest electrorheological response has been revealed for titanium dioxide modified with aluminum oxide at an Al content of 6.5–7.0 mol % relative to TiO2. 相似文献
8.
A. Yu. Vakhrushev V. V. Gorbunova T. B. Boitsova V. M. Stozharov 《Russian Journal of General Chemistry》2016,86(4):792-797
Phase composition and structure of mesostructured materials, titanium dioxide and titanium dioxide modified with silver nanoparticles, have been studied by X-ray diffraction analysis. Introduction of Ag(I) ions into the initial composition and variation of the annealing temperature over the 500–950°C range allows controlling the anatase to rutile crystal phase ratio in the samples. The photocatalytic activity of TiO2 and TiO2/Ag samples has been demonstrated using the methyl orange degradation reaction. The catalytic properties of the materials have been found to depend on the anatase to rutile phase ratio and on the presence of silver nanoparticles. 相似文献
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Hadi Fallah Moafi Abdollah Fallah Shojaie Mohammad Ali Zanjanchi 《Journal of Thermal Analysis and Calorimetry》2011,104(2):717-724
We have investigated the effect of titanium dioxide as a durable finish on the flammability and photocatalytic self-cleaning
of cellulosic fabric. Nano-sized titanium dioxide particles were successfully synthesized and deposited onto cellulosic fibers
with good compatibility, significant photocatalytic self-cleaning activity, and flame-retardancy properties using the sol–gel
process at low temperature. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under
ultraviolet–visible illumination, and also flame-retardancy effect was tested by flammability tester. The samples have been
characterized by several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance
spectroscopy, X-ray diffraction, and thermogravimetric analysis. The titanium dioxide nanoparticles with 10–20 nm in size
have been found to form a homogeneous thin film on the fiber surface which shows efficient photocatalytic and flame-retardancy
properties. This preparation technique can also be applied to new fabrics to create self-cleaning and flame-retardancy properties
in them. 相似文献
11.
Preparation and investigation of structural and photocatalytic properties of phosphate modified titanium dioxide 总被引:2,自引:0,他引:2
Lszl Krsi Imre Dkny 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):146-154
A series of high surface area titanium dioxide samples (P-TiO2) with varying phosphate content have been prepared by the sol–gel technique. The structural characterization of the samples included X-ray powder diffraction, diffuse reflectance infrared and UV–vis spectroscopy (DRIFT and UV–vis–DR), and nitrogen adsorption measurements. The structural properties of the P-TiO2 samples significantly changed with the phosphate content and calcination temperature. According to XRD data the presence of phosphate shifts the anatase rutile phase transition to higher temperatures, revealing that phosphate improves the thermal stability of the samples. The specific surface area and the semiconductor band gap energy increase with the phosphate content.
The photocatalytic activity of TiO2 and P-TiO2 was studied by phenol degradation in liquid phase. A small amount of phosphate of the catalysts increases the photocatalytic activity, but further increase of the P/Ti molar ratio (above 0.01), leads to a considerable loss in activity. The optimal calcination temperature of P-TiO2 was 300–500 °C. The phenol conversion rate is highest with catalysts calcined at 700 °C, but phenol does not degrade to carbon dioxide. 相似文献
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Nano-sized rod-like titanium dioxide (TiO2) filled rigid poly(vinyl chloride) (PVC) nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr (parts per hundreds of resin) could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness. 相似文献
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Titanium dioxide with a mesoporous structure, when photoactivated in water, demonstrates an unprecedented photocatalytic activity, driven strongly by an adsorption degree of molecules onto the catalyst surface, which promotes a preferential conversion of a well-adsorbed molecule. This catalyzes a selective transformation of a well-adsorbed molecule into a less-adsorbed molecule, so-labeled "stick-and-leave" transformation, which promotes a direct hydroxylation of benzene to phenol, one of the most difficult synthetic reactions, with very high selectivity (>80%) and using water as a source of oxidant. 相似文献
14.
以乙酰丙酮稀土和乙酰丙酮铁配合物通过吸附法对纳米TiO2进行表面改性,以光催化降解甲基橙为探针反应,在紫外光照条件下考察了改性条件对纳米TiO2催化活性的影响,包括金属元素种类、配合物含量、吸附温度、溶剂用量、吸附时间等.研究表明,乙酰丙酮铁改性纳米TiO2最有效.当w[Fe(acac)3/TiO2]为0.25%,吸附温度为60℃,溶剂用量为乙醇/TiO2等于29 mL/g,吸附1.5 h时,改性后的纳米TiO2催化活性比改性前有了很大的提高.即使在普通白炽灯光照条件下,改性催化剂仍显示出很高的光催化活性,明显优于非改性的纯TiO2.改性纳米TiO2经过IR、XRD、UV-Vis、荧光、SEM-EDS和高倍光学显微镜等分析表征. 相似文献
15.
A. L. Volynskii D. A. Panchuk A. V. Bol’shakova L. M. Yarysheva N. F. Bakeev 《Colloid Journal》2011,73(5):587-604
Results of studies aimed at developing a new approach to measuring stress-strain properties of nanosized solids (strength,
yield stress, and the value of plastic deformation at uniaxial tension) are generalized. This approach is based on the analysis
of the parameters of microrelief arising upon the deformation of polymer films with thin coatings. It is demonstrated for
the first time that the stress-strain properties of aluminum coatings deposited onto Lavsan substrates depend on the level
of stresses in the substrate, the value of its deformation, and the thickness of the coating. The evolution of these parameters
is related to the strain hardening of metal and the effect of nanostructuring of crystalline materials in the range of small
thicknesses. When precious metal (Au, Pt) nanosized films are deposited onto polymers by ion-plasma sputtering, in the course
of metal deposition, polymer surface layers interact with cold plasma. Stress-strain properties of polymer surface layers
modified by plasma are quantitatively estimated for the first time. The model is proposed that makes it possible to take into
account the contribution of the properties of precious metal and plasma-modified polymer surface layer to the strength of
the coating. 相似文献
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A sonochemical-hydrothermal method for preparing fluorinated mesoporous TiO2 microspheres was developed. Formation of mesoporous TiO2 and doping of fluorine was achieved by sonication and then hydrothermal treatment of a solution containing titanium isopropoxide, template, and sodium fluoride. The as-synthesized TiO2 microspheres were characterized by X-ray diffraction (XRD), Fourier translation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, photoluminescence spectroscopy (PL), and BET surface areas. The P123 template was removed completely during the hydrothermal and washing steps, which was different from the conventional calcination treatment. The as- synthesized TiO2 microspheres had good crystallinity and high stability. Results from the photocatalytic degradation of methylene blue (MB) showed that fluorination could remarkably improve the photocatalytic activity of titanium dioxide. 相似文献
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《Journal of Molecular Catalysis #》1992,71(1):129-147
Titanium silicalites with different titanium contents were synthesized according to two hydrothermal procedures. The materials were subjected to physicochemical characterization and tested as catalysts for partial oxygenations by aqueous hydrogen peroxide. The role of isolated titanium, finely divided titanium dioxide and residual acidity in the catalytic behavior of titanium silicalites is discussed and a mechanistic model for the oxidation reactions is proposed. 相似文献
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Xiaogang Sun Jun Xing Jingping Qiu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(6):1151-1156
A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV–Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants. 相似文献
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The first step of the photocatalytic degradation of methylene blue (MB) on anatase is photocatalytic reduction with subsequent
decomposition of the dye itself and its leucobase. At low catalyst concentrations (≤2 g/L), the dye decomposition rate constant
increases with increasing anatase concentration. A plateau appears for anatase concentrations above 2 g/L. Under steady-state
conditions, the reaction kinetics is described by the Michaelis–Menten equation if the catalyst concentration is significantly
greater than the MB concentration, which permits us to determine the kinetic parameters of the degradation process. 相似文献