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Abstract  

The adsorption behaviour of99Mo in the form of molybdate and of99mTc in the form of pertechnetate on hydrated titanium dioxide was investigated at different molarities of hydrochloric acid. The adsorption capacity of molybdate on hydrated TiO2 is higher than on Al2O3. A99mTc-generator is suggested. This generator is based on the adsorption of (99Mo) molybdate on hydrated TiO2, at acidities of 0.05–0.1M. HCl.99mTc is eluted with 0.9% NaCl. Radionuclidic, radiochemical and chemical purities of the eluates were checked. This generator seems to have a great potential as compared to the traditional alumina generators.

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. A DAMS , L. K. , L YON , D. Y. & A LVAREZ P. J. J. , 2006 . Comparative eco-toxicity of nanoscale TiO 2 , SiO 2 , and ZnO water suspensions . Water Research . 40 . 3527 – 3532

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Journal of Thermal Analysis and Calorimetry
Authors:
V. Yanishpolskii
,
A. Pavlenko
,
V. Tertykh
,
V. Il'in
,
R. Leboda
, and
J. Skubiszewska-Zieba

Abstract  

Mesoporous titanium-containing silicas with TiO2 contents from 1 up to 70 mol% were prepared. The obtained samples have been characterized by the powder X-ray diffraction data, the diffuse reflectance infrared Fourier transform method, and nitrogen adsorption at 77 K. Specific surface area, total pore volume, distribution pore volume on pore sizes were determined from nitrogen adsorption isotherm for synthesized titanosilicas.

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Abstract  

The changes of physico-chemical properties of mechanochemically pretreated (BaCO3 +TiO2 +PbO) powders were investigated. The values of apparent activation energy of BaTiO3 formation calculated by the Freeman and Carroll method decrease with milling time. The changes of precursors density may be interpreted as a consequence of mechanochemical reactions during milling.

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Abstract  

Results of Carr and Galwey [1] concerning copper malonate (CM) decomposition in vacuo at 510 K prompted present studies on the utility of CM as a low-temperature precursor of oxide-supported copper catalysts. CM deposited upon metal oxides has been converted to copper particles by vacuum thermal decomposition or reduction with aqueous hydrazine. Using the dehydrogenation of isopropanol to acetone as a catalytic probe reaction, comparisons are made between levels of catalytic activity and selectivity induced in TiO2, MgO and Ca(OH)2 supports by copper deposited thereon. Effects of particle size, prereduction temperature, and support reducibility are described and evidence is given for a strong metal support interaction (SMSI)-like inhibition of activity of Cu/TiO2 by prior high temperature reduction.

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Abstract  

Differential thermal analysis was carried out on the self-propagating high-temperature synthesis reaction 3TiO2+4Al+3C→3TiC+2Al2O3. The results allow the ignition temperature of the reaction to be estimated and the reaction mechanism to be identified. The ignition temperature was 900°C and the results suggest that the reaction proceeds by an initial reaction between titania and aluminium (3TiO2+4Al→3Ti+2Al2O3) and the titanium formed reacts with the carbon (Ti+C→TiC).

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Abstract  

The conditions to fabricate the bulk porous specimens have been studied on account of sodium borosilicate (NBS) glasses. Glass composition, heat treatment at phase separation and TiO2 addition have been considered in this study. Original glass samples of composition in mol%: sample A: 9.19 Na2O - 23.58 B2O3 - 67.23 SiO2, sample B: 9.29 Na2O - 3.17 TiO2 - 23.82 B2O3 - 63.72 SiO2 were prepared by melting reagent grade chemicals (Na2CO3, HBO3, SiO2 and AgNO3) in platinum crucibles at 1480C for 1 h in air. The melts were poured onto stainless steel plates and were annealed at 500C for 0.5 h after cooling. Thus, obtained samples were phase separated at 700C for 2, 15, 25 and 50 h to study their microstructure by scanning electron microscope (SEM). Besides the direct study of the microstructure by SEM, information on glass structural changes of samples are provided by measuring in situ changes by the optical transmittance thermal analysis. The isothermal measurements were carried out at 700, 720 and 740C. The temperature of phase separation, the leaching and nucleator addition (TiO2), significantly influence the microstructure of the resulting leached product. TiO2 additive seems to suppress crystallization of cristobalite: especially at the extended above heat treatment phase separation runs. The phase-separated domains of glasses containing above 80 moles of SiO2 are so small that it is very hard to observe them by SEM. The glass composition in our case was selected in a way to have relatively large phase separated areas easily observed by SEM at magnification 20 000. The influence of TiO2 is not too pronounced. It seems to suppress the cristobalite crystallization, especially of longer heating runs. The image analysis of leached glasses shows the prevailing content of the skeletal phase in a comparison to pores. The TiO2 content diminishes the content of the skeletal phase.

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Abstract  

The present work describes the application of radiotracer technique for studying uptake of arsenic on titanium hydroxide, commercial titanium dioxide (TiO2) powder (anatase) and synthesized mesoporous titania beads in acidic, neutral, and alkaline conditions. Sol–gel templating method was used to prepare titania–polysaccharide composites, with different polymer contents. Mesoporous titania was obtained by heat treatment of the composite beads in a controlled environment. The synthesis process was optimized, using thermogravimetry analysis. X-ray diffraction patterns confirmed the formation of anatase pure phase titania (TiO2) at 700 °C in different environments, and scanning electron microscopy studies confirmed uniform pore size distribution. The effect of surface area, polymer content and pH on uptake of arsenic(III) and (V) on the synthesized titania beads was also investigated. Arsenic(V) was found to be retained quantitatively on the titania beads synthesized from 0.8% polymer content titania–polymer composite precursor in neutral to alkaline conditions. Details of the results obtained are discussed.

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Abstract  

The crystallization kinetic of the basalt glass ceramic of the oxide composition, (%): SiO2 − 50.82; Al2O3 − 12.05; Fe2O3 − 9.28; CaO − 15.48; MgO − 11.08; Na2O+K2O − 1.14; TiO2 − 0.15, with addition of 10% TiO2 as nucleating agent has been studied using thermal analysis under non-isothermal conditions. In this order, the non-isothermal DTA curves were obtained at different heating rates between 4 and 20°C min−1 in the temperature range of 25–1000°C using a Derivatograph-C (MOM, Hungary). The kinetic parameters of the crystallization process were calculated on the basis of Ozawa-Flynn-Wall, Friedman, Budrugeac-Segal and non-parametric kinetic methods.

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Abstract  

Emanation thermal analysis (ETA) was used in the characterization of microstructure changes during heating ofprecursors for the titania based materials: hydrous titania, TiO2 nH2O (n=0.58) and hydrous titania containing 10% ruthenia,(TiO2)0.9(RuO2)0.1 nH2O (n=1.5). The precursors were heated at the constant rate 6 K min–1 in argon flow in the range 20–1000°C. ETA results were compared with the theoretical curves simulating the temperature dependences of radon release rate, E(T). Two mathematical models were used in the simulation. The models considered either subsequent or simultaneous solid state processes (i.e. dehydration, crystallization orphase transition, resp.) during thermal treatment of titania based materials. A good agreement was found between experimental and the simulated ETA curves. The results of ETA were confirmed by XRD patterns of intermediate products of thermal treatment of the precursors.

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