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A synthesis of highly dispersed nanocrystalline materials based on titanium dioxide in aqueous media at neutral pH has been developed. The surface modification of TiO2 with tiron, ascorbic acid and rutin afforded colored, transpar...
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A synthesis of highly dispersed nanocrystalline materials based on titanium dioxide in aqueous media at neutral pH has been developed. The surface modification of TiO2 with tiron, ascorbic acid and rutin afforded colored, transparent, colloidal solutions. Stability of yellow-orange colloids at pH = 7 has been achieved. Photoactivity of materials has been assessed by photocurrent measurements. For all modified materials visible light induced photocurrents have been recorded. The photocurrents were significantly amplified in the presence of dissolved oxygen due to O2 reduction to superoxide. The studied materials have been used to prepare thin films on glass substrates applying spin coating technique. Fabrication of visible light responsive thin films, well bound to the substrate, involves synthesis of films of unmodified TiO2, followed by their sintering and impregnation with the solutions of modifiers. SEM images showed the formation of compact layers of titanium dioxide with particles of diameter within 15-30nm. The photocatalytic activity of synthesized films has been demonstrated in the reaction of terephthalic acid oxidation to 2-hydroxyterephthalic acid, proving photogeneration of hydroxyl radicals upon visible light irradiation (λ > 400 nm).
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The purpose of this work is to design and develop a series of stable and effective TiO2 photocatalysts prepared by a modified precipitation method. In order to improve the photo response of the TiO2 to the visible region, the effe...
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The purpose of this work is to design and develop a series of stable and effective TiO2 photocatalysts prepared by a modified precipitation method. In order to improve the photo response of the TiO2 to the visible region, the effect of addition of six successive transition metal elements of fourth period, namely chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) was studied. Two different types of dyes, methyl orange (MO, azo dye) and methylene blue (MB, thiazine dye group), were used to investigate the influence of structure of dyes on the photocatalytic degradation rates. The results showed that loading titania with 0.3 wt.% of different transition metal elements was found to have significant influences on the crystallographic structure, physical properties and optical absorption properties of titania based catalysts, as well as catalytic activity during dye degradation reactions. The optical reflection edge was obviously shifted to the visible light range with the transition metal additives. The band gap energies of the doped TiO2 samples were considerably narrower than that of plain TiO2. The different activity levels of the catalysts for both dyes clearly show that the photocatalytic activity of samples strongly depended on the metal dopant used. Among all the catalysts, Cu/TiO2 sample exhibited the highest photocatalytic activity under visible light for both of the dyes owing to the low band gap energy and delayed electron-hole recombination. (C) 2015 Elsevier B.V. All rights reserved.
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The making of TiO2/resin, TiO2/zeolite dan TiO2/activated carbon as photocatalyst that will characterize with X Ray Diffraction (XRD) and Band Gap Energy (Eg) has been done. The characterization aims to find out the formation and ...
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The making of TiO2/resin, TiO2/zeolite dan TiO2/activated carbon as photocatalyst that will characterize with X Ray Diffraction (XRD) and Band Gap Energy (Eg) has been done. The characterization aims to find out the formation and to determine the level of band Gap energy in each of photocatalyst where the higher band gap energy then photoreduction effectiveness will be higher. XRD and Band Gap Energy (Eg) characterization showed that the photocatalyst (TiO2/resin, TiO2/zeolite dan TiO2/activated carbon) has been formed while the results of the band gap energy of TiO2/zeolite, TiO2/resin and TiO2/activated carbon is 3.608 eV, 3.38 eV, and 3.48 eV. Based on the expected value Eg photocatalytic activity of TiO2/zeolite is higher than the other photocatalyst. Photocatalytic activity test carried out by reacting 50 mg each photocatalyst to reduce 50 ml of Hg (II) of 5 ppm is illuminated by sunlight as a light source with a variation of exposure time (1,2,3,4,5 and 6 hours). From the results indicate that the higher radiation exposure time the higher percentage Hg(II) reduced. In this research TiO2/zeolite has an optimum photocatalyst with exposure time 6 hours and 98,5% photoreduction affectivity. At this stage also studied the effect of the concentration of ions Hg (II) (0; 2.5; 5; 10; 20; and 25) with 6 hours of exposure time. The data obtained showed that the higher the initial concentration of ions Hg (II), the lower the Photoreduction effectiveness.
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TiO2 quantum dot(QD)size nanoparticle colloids have shown tremendous photochromic response.Here we show that thethe photochromic responseTiO2 QDs can be further enhanced by doping.Our synthesis approach allows to reach high nomina...
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TiO2 quantum dot(QD)size nanoparticle colloids have shown tremendous photochromic response.Here we show that thethe photochromic responseTiO2 QDs can be further enhanced by doping.Our synthesis approach allows to reach high nominal doping level by substituting up to 20 %Ti in TiO2 without phase segregation simultaneously keeping particles in ultra-small.We compare the effectdifferent dopants(Nb~(5+),Hf~(4+)and Ta~(5+))on photochromic propertiesTiO2 QDs.We show all dopants in study enhance the response kinetics and total transmittance change.From all three dopants,Nb~(5+)provides strongest response and fastest coloration while Hf~(4+)doped TiO2 QDs exhibit fastest recovery when the UV light is of f.The presented insight in photochromic propertiesdoped TiO2 QDs will allow to develop photochromic devices and materials with better performance.
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The one dimension (1D) TiO2 nanotubes and nanorods were successfully prepared via a one-step hydrothermal method. The structure and properties of the catalysts were characterized by means of X-ray diffraction (XRD), field emission...
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The one dimension (1D) TiO2 nanotubes and nanorods were successfully prepared via a one-step hydrothermal method. The structure and properties of the catalysts were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), N-2 adsorption-desorption, UV-vis diffuse reflectance and photoluminescence (PL) spectroscopy. Meanwhile, the photoelectrochemical properties were recorded through Mott-Schottky, transient photo-current responses and electrochemical impedance spectroscopy curves (EIS). The results showed that 1D TiO2 nanostructures catalysts had a high specific surface area, enhanced visible light response and superior electron transport properties. The photocatalytic activities of catalysts for reduction CO2 were investigated under 9 h irradiation of a 300 W Xe arc lamp equipped with UV 420 nm bandpass filter. The maximum yields of CH4 over the TiO2 nanotubes (TNT) and TiO2 nanorods (TNR) were 19.16 mu mol/g.cat and 12.71 mu mol/g.cat, respectively, which were approximately 2.33 folds and 1.48 folds higher than TiO2 nanoparticles (TNP). The enhanced photocatalytic activity of TiO2 nanotubes and nanorods could be ascribed to the presence of oxygen vacancies and defects formed during the calcination process and its special structures, which accelerates the transfer of electrons. Besides, the better activity of TNT than TNR may be ascribed to its unique hollow tubular structure and larger surface area.
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This paper presents, for the first time, the synthesis, via aerosol-assisted (AA) CVD followed by annealing at 620 degrees C for 5 h, of pure Fe2TiO5 thin films on glass. The thin film is deposited from a one pot solution containi...
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This paper presents, for the first time, the synthesis, via aerosol-assisted (AA) CVD followed by annealing at 620 degrees C for 5 h, of pure Fe2TiO5 thin films on glass. The thin film is deposited from a one pot solution containing titanium isopropoxide and tris(acetylacetonato) iron in an ethyl acetate solvent. The film is characterized using a range of techniques including powder X-ray diffraction(XRD), wavelength dispersive X-ray (WDX) spectroscopy, X-ray photoelectron spectroscopy(XPS), scanning electron microscopy (SEM), and UV-vis spectroscopy. The photocatalytic activity of the film under UVA and visible light irradiation is also tested. The results show that Fe2TiO5 is able to degrade resazurin redox dye under UVA illumination at a rate much higher than Pilkington NSG Activ (TM), with a formal quantum efficiency (FQE) an order of magnitude superior.
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This study is carried out to investigate the effect of the cathodic contribution in the performance of electro-oxidation process for decolorization of the textile wastewater effluent pre-treated with a lab-scale moving bed-membran...
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This study is carried out to investigate the effect of the cathodic contribution in the performance of electro-oxidation process for decolorization of the textile wastewater effluent pre-treated with a lab-scale moving bed-membrane bioreactor. For this purpose, titanium dioxide (TiO2) was used as anode electrode and four different cathodic electrode materials: Graphite, TiO2, TiO(2-)coated Platine, and TiO(2-)coated ruthenium dioxide (RuO2) (namely RuO2) were tested and compared for their color removal efficiencies. Besides, the optimization parameters that affect color removal in correspondence to the electrode materials, such as applied current, electrolysis time, and pH were studied. In this context, the optimum parameters for each electrode material were selected, and the color removal percentages were found as 92.95%, 91.58%, 91.40%, and 89.17% for TiO2/Graphite, TiO2/Platine, TiO2/TiO2, and TiO2/RuO2, respectively. Finally, the operational cost for each of the tested cathodic electrode materials was calculated in each of the studied optimization parameters making it easier and practical for the selection and evaluation of the electrode materials by the readers. The correlation coefficients (R-2) were 81.2%, 87.1%, 86.7%, and 88.6% respectively as a result of the optimization study using the nonlinear regression modeling.
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In this study, TiO2, ZnO, TiO2/ZnO (Ti/Zn), and TiO2/ZnO/Sep (Ti/Zn/Sep) catalysts have been synthesized using sol-gel and chemical precipitation method. Their photocatalytic performances have been compared using Flumequine (FLQ) ...
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In this study, TiO2, ZnO, TiO2/ZnO (Ti/Zn), and TiO2/ZnO/Sep (Ti/Zn/Sep) catalysts have been synthesized using sol-gel and chemical precipitation method. Their photocatalytic performances have been compared using Flumequine (FLQ) antibiotic. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), N-2-adsorption, and the determination of a zero point charge has been used to characterize the synthesized catalysts. The degradation studies showed that the catalytic efficiency of Ti/Zn/Sep is higher than that for other catalysts. The operational parameters such as pH, initial FLQ concentration, and catalyst dosage were evaluated. UV-vis and high-resolution mass spectroscopy (HRMS) analyses were used to determine the degradation efficiency and products. ZnO played a major role in the FLQ degradation process, and sepiolite contributed to adsorption of FLQ on the catalyst surface enormously. The catalysts exhibited 11%, 23%, 63%, and 85% degradation efficiency for ZnO, TiO2, Ti/Zn, and Ti/Zn/Sep in the decomposition of FLQ, respectively.
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In this study, a comparison of the photocatalytic activity efficiency of the catalysts WO3/TiO2, Fe2O3/TiO2, and TiO2 in the degradation of the herbicide 2,4-D and its main by-product (2,4-dichlorophenol, 2,4-DCP), under natural s...
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In this study, a comparison of the photocatalytic activity efficiency of the catalysts WO3/TiO2, Fe2O3/TiO2, and TiO2 in the degradation of the herbicide 2,4-D and its main by-product (2,4-dichlorophenol, 2,4-DCP), under natural sunlight, visible, and UV light, was carried out. The catalysts were synthesized by the sol-gel method. All the catalysts showed anatase crystalline phase, and they exhibited similar values of band gap, specific surface area, and crystallite size; however, different photocatalytic activity was observed under the different light sources. Complete degradation of 2,4-D and near to 89% of mineralization using WO3/TiO2 and Fe2O3/TiO2 was achieved after 150 min under solar light, while using TiO2 sol-gel, lower degradation rate was obtained. By using artificial light (UV and visible lamp), the degradation and mineralization rates were lower than those obtained under natural sunlight. The produced 2,4-DCP intermediate was completely degraded after 240 min under sunlight only with the modified catalysts.
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