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Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple external gelation process, taking full advantage of the gelation features of titanium and silica, was developed to prepare TiO2-SiO2 mixed gel spheres suitable for strontium adsorption. The source solutions used for the process were prepared from different mixtures of 1M TiCl4 and 1M Na2SiO3 solutions and converted into droplets in a gelation column. The suitable spheres for strontium adsorption were obtained using a hexone (methyl isobutyl ketone) solution as the drop formation medium and ammonia as the gelling agent. The mixed oxide gels were identified and characterized by DTA/TGA, FTIR and XRD analysis. The parameters affecting the strontium adsorption, such as weight ratio of TiO2, pH, temperature, shaking time and selectivity towards competing ions were investigated. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin-Radushkevich equations. Thermodynamic parameters for the sorption system have been determined at four different temperatures. The value of DeltaH degrees =39.553 kJ/mol and DeltaG degrees =-16.687 kJ/mol at 296 K prove that the sorption of strontium on mixed oxide gel is an endothermic and a spontaneous process.
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PMID:Preparation of TiO2-SiO2 mixed gel spheres for strontium adsorption. 1581 74

The hybrid microspheres with polystyrene core coated by titania nanoparticles were prepared by miniemulsion polymerization, and the as-prepared samples were characterized by SEM, XRD, TG-DTA, XPS, and SPS techniques. TiO2 nanoparticles experienced two processes of phase transition, i.e., amorphous to anatase and anatase to rutile at the calcining temperature range from 400 to 1000 degrees C. The phase transformation temperature of TiO2 hybrid microspheres from anatase to rutile was increased by about 300 degrees C due to the blocking function of calcined polymer remainder. SPS results present that the band-gap of hybrid microspheres is 3.2-3.4 eV, which is larger than that of pure TiO2. The maximum intensity of the SPS signal is about 3 times larger for the hybrid material as compared to the pure TiO2. In addition, the photocatalytic degradation rate of TiO2 hybrid microspheres was 15% faster than that of pure TiO2 in the experiment of the photocatalytic degradation of methyl orange.
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PMID:Crystallization and photovoltaic properties of titania-coated polystyrene hybrid microspheres and their photocatalytic activity. 1685 28

The synthesis of TiO2 and Fe-TiO2 by sol-gel method is demonstrated and characterized. The characterization of TiO2 and Fe-TiO2 is performed with instruments, including TGA/DTA, FTIR, UV-Vis, N2 adsorption and SEM. Dichloromethane is used for the photocatalytic activity test. From the results of dichloromethane photocatalytic degradation, the calcined temperature of TiO2 and the presence of water vapor influence the photocatalytic activity. The optimum doping amount of iron ions is 0.005 mol%, and this can enhance the photocatalytic activity, while too great an amount will make the iron ions become recombination centers for the electron-hole pairs and reduce the photocatalytic activity. UV-Vis diffuse reflectance spectra of Fe-TiO2 show an increase in absorbency in the visible light region with the increase in iron ions doping concentration The intermediate of dichloromethane photodegradation includes CHCl3, CCl4, CH2Cl2 and COCl2. The presence of iron ions may reduce the adsorption of Cl element on the surface of the photocatalyst.
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PMID:Study on photocatalytic degradation of gaseous dichloromethane using pure and iron ion-doped TiO2 prepared by the sol-gel method. 1709 38

A new glass electrolyte formed by constant amounts of titanium oxide (TiO2) and various amount of phosphotungstic acid (PWA) doped P2O5-SiO2 is prepared using the sol-gel process. The structural formation is confirmed by Fourier infrared spectroscopy (FTIR) and from thermogravimetric and differential thermal analysis (TG/DTA) measurements, the glasses display good thermal stability. Further characterisation is undertaken by N2 adsorption/desorption measurements, proton conductivity and hydrogen permeability analyses and a H2/O2 fuel cell test is also performed. The glass materials with large pores and specific surface area are suitable for use as the electrolyte in H2/O2 fuel cells. The effect of TiO2 processing with constant amount of PWA in phosphosilicate glasses, is investigated and discussed. The hydrogen permeability is 1.57x10(-11) mol cm(-1) s(-1) Pa(-1) at 110 degrees C for 0.8 mm thick glass; a power density of 46.3 mW cm(-2) at 125 mA cm(-2) and a current density of 175 mA cm(-2) is obtained (T=28 degrees C, relative humidity).
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PMID:Development of new glass composite membranes and their properties for low temperature H2/O2 fuel cells. 1787 56

Anatase-type TiO2 single nanocrystals with boatlike, comblike, sheetlike, leaflike, quadrate, rhombic, and wirelike particle morphologies were prepared by hydrothermal treatment of a layered titanate nanosheet colloidal solution. The formation reactions and surface properties of the TiO2 nanocrystals were investigated using XRD, TEM, TG-DTA analyses, and measurements of BET specific surface area, photocatalytic activity, and ruthenium dye (N719) adsorption. The crystal morphology can be controlled by reaction temperature, pH value of reaction solution, and exfoliating agent. The titanate nanosheets were transformed to the TiO2 nanocrystals by two types of reactions. One is an in situ topotactic structural transformation reaction, and the other is a dissolution-deposition reaction on the surface. The anatase nanocrystals formed by the in situ topotactic structural transformation reaction retain the sheetlike particle morphology of the precursor, and they preferentially expose the (010) plane of anatase structure. The crystal surface of anatase nanocrystals prepared in this study showed higher photocatalytic activity and higher ruthenium dye adsorption capacity than did the Ishihara ST-01 sample, a standard anatase nanocrystal sample. The results indicated the (010) plane of the anatase structure has high photocatalytic activity and high ruthenium dye adsorption ability.
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PMID:Single nanocrystals of anatase-type TiO2 prepared from layered titanate nanosheets: formation mechanism and characterization of surface properties. 1793 63

In this work, Fe-doped mixed crystal TiO2 powder as sonocatalyst was prepared by the sol-gel method and heat treatment, and a novel method combined with ultrasonic irradiation was propounded to degrade the organic polluted water. First, the Fe-doped mixed crystal TiO2 powder was characterized by TG-DTA, XRD, and TEM techniques. Ultrasound was used as the irradiation source and the azo fuchsine was chose as the model compound. Then a series of degradation experiments was carried out in the presence of Fe-doped mixed crystal TiO2 powder. Also, the degradation process and some influencing factors, such as irradiation time, doping Fe3+ ion content, added amount of catalyst, and initial concentration of azo fuchsine solution, on the degradation were investigated by UV-vis spectra, ion chromatography, and HPLC. Through the degradation of azo fuchsine, it was found that the combination of ultrasonic irradiation and Fe-doped mixed crystal TiO2 powder can completely degrade the azo fuchsine in aqueous solution. Because of the good degradation efficiency, this method may be an advisable choice for the treatments of non- or low-transparent wastewaters in the future.
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PMID:Preparation of Fe-doped mixed crystal TiO2 catalyst and investigation of its sonocatalytic activity during degradation of azo fuchsine under ultrasonic irradiation. 1820 58

Nitrogen-doped nanosize TiO2 was prepared by sol-gel method with TBT and EDA as forerunner body, ethanol as solvent and glacial acetic acid as inhibitor. The crystalline structure and spectrum character were characterzed. According to the curves of differential thermal gravimetric analysis (TG/DTA), the crystal transformation temperature and the best calcining temperature of the obtained samples were determined. According to the ultraviolet-visible diffuse reflection spectrum (UV-Vis/ DRS), the spectral absorption characteristic of the obtained samples was characterized; According to the X-ray diffraction spectrum (XRD), the particle size and crystalline phase structure of the prepared samples were determined; and according to the X-ray photoelectron spectrum (XPS), the superficial composition of the prepared samples was analyzed. The relations between the red shift degree of absorption band and the proportion of EDA/TBT and calcining temperature were investigated in this experiment. The results indicate that the crystal phase of the obtained nitrogen-doped TiO2 is anatase, and the absorption band has a red shift obviously. Both the proportion of EDA/TBT and the calcining temperature have an evident effect on the spectral absorption of the prepared samples. When the mol proportion of EDA/TBT is 1 : 10 and the calcining temperature is 600 degrees C, the spectral absorption of the prepared samples is the strongest.
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PMID:[Preparation of N-doped nanosize TiO2 and spectral analysis]. 1847 25

In the paper, undoped and Pr2O3 doped TiO2 nanoparticles were prepared by a sol-gel process using Ti(OC4H9)4 as raw material and characterized by means of XRD TG-DTA, AFM, UV-Vis and FTIR. The photocatalytic activity of Pr2O3/TiO2 was evaluated by the photocatalytic degradation of acidic fuchsine. The factors affecting on photocatalytic activity of Pr2O3/TiO2, such as the content of doped Pr2O3, the calcined temperature and added amount of the catalyst etc. were discussed. It was shown that Pr doping hampers the transformation of TiO2 crystal phase from anatase to rutile, and with Pr2O3 doping the particle diameter of Pr2O3/TiO2 samples decreased, the specific surface area increased and the photocatalytic activity improved. When doping amount of Pr is 0.8%, added amount of the catalyst is 0.03 g and the calcination temperature is 500 degrees C, the degradation efficiency of acidic fuchsine reaches 97%. The photocatalytic degradation of acidic fuchsine by Pr2O3/TiO2 is a quasi-first order dynamic reaction.
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PMID:[Preparation and catalytic activity for degradation of acidic fuchsine of TiO2 photocatalyst]. 1861 30

TiO2 pillared montmorillonite composite photocatalyst was synthesized by acid-catalyzed sol method and characterized by IR, UV-Vis, TG/DTA, XRD, SEM etc. Spectral analyses have demonstrated that TiO2 pillared montmorillonite(Ti-MMT) has wider interlayer distance than Na substituted montmorillonite (Na-MMT) and higher optical absorption efficiency than nanoscale anatase TiO2. The photocatalytic degradation reaction of acidic fuchsine by sunlight was employed to evaluate the catalytic activity of the composite catalyst. It was found that, besides easy reclaimation, the photocatalytic activity of the catalyst was much higher than that of the pure nanosized anatase TiO2. When the addition amount of Ti-MMT is 0.2 g x (100 mL)(-1) and pH of acidic fuchsine solution is 3, the dye could be degraded thoroughly in 40 min and the degradation reaction obeys Langmuir- Hinshelwood equation.
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PMID:[Preparation of TiO2 pillared montmorillonite photocatalyst and its photocatalytic activity to degradation reaction of acidic fuchsine by sunlight]. 1872 Aug 15

A series of mesoporous titania materials modified with tungstophosphoric acid (TPA) were successfully synthesized by using urea as low-cost template via sol-gel reactions, followed by removing the urea by extraction with water. They were characterized by FT-IR, 31P MAS-NMR, XRD, DTA-TGA, DRS, TEM and BET. The samples presented mesopores with a diameter higher than 3.0 nm. The S(BET) of the solids decreases with the increase of the TPA content and with the increase of the calcination temperature. According to FT-IR and 31P MAS-NMR studies the main species present in the samples is [PW12O40]3- anions, which was partially transformed into [P2W21O71]6- and [PW11O39]7- anion during the synthesis and drying step. The XRD patterns of the modified samples only exhibited the characteristic peaks of anatase phase. The presence of TPA retarded the crystallization of the anatase phase and its transformation into rutile phase. The point of zero charge decreased in parallel with the increment of tungstophosphoric acid in the samples and with the increase of the calcination temperature. The band gap energy decreased as a result of the introduction of TPA into the TiO2 matrix, but remained practically constant with the increase of the calcination temperature.
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PMID:Direct modification with tungstophosphoric acid of mesoporous titania synthesized by urea-templated sol-gel reactions. 1879 Apr 94


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