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Journal of Radioanalytical and Nuclear Chemistry
Authors: Sharayu Kasar, Sumit Kumar, Aishwarya Kar, K. Krishnan, N. Kulkarni, and B. Tomar

Abstract  

Sorption of Eu(III), an analogue of trivalent actinides (Am, Cm), by amorphous titania as well as different crystalline phases of titania, namely anatase and rutile, have been studied as a function of pH, using 154Eu (half life = 8.8 yrs, Eγ = 123,247 keV) as a radiotracer. The objective of this study was to investigate the effect of the crystalline phase of the titania on their sorption behaviour towards the metal ion. Amorphous titania was prepared by organic route and was converted into anatase and rutile by heating at elevated temperatures based on the differential thermal analysis studies. Eu(III) sorption by all forms of titania rises sharply with the pH of the suspension, with the sorption edge shifting to higher value in the order; amorphous < anatase < rutile. However, the normalization of the sorption data to the surface area of the sorbents resulted in the overlapping of the sorption curves for amorphous and anatase phases, with the data being higher for rutle in the lower pH region, indicating the effect of the crystal phase on sorption behaviour of Eu(III).

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Anatase and rutile powders prepared by various methods were characterized by thermoanalytical studies up to 1400 °C using a simultaneous TG-DTG-DTA apparatus. Preparation techniques were developed for the manufacture of amorphous titania, pure anatase, stabilized anatase and pure rutile.

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Journal of Thermal Analysis and Calorimetry
Authors: János Madarász, Ana Brăileanu, Maria Crişan, Malina Răileanu, and György Pokol

Abstract  

Thermal decomposition of an amorphous precursor for S-doped titania (TiO2) nanopowders, prepared by controlled sol–gel hydrolysis–condensation of titanium(IV) tetraethoxide and thiourea in aqueous ethanol, has been studied up to 800 °C in flowing air. Simultaneous thermogravimetric and differential thermal analysis coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR) have been applied for analysis of released gases (EGA) and their evolution dynamics in order to explore and simulate thermal annealing processes of fabrication techniques of the aimed S:TiO2 photocatalysts with photocatalytic activities under visible light. The precursor sample prepared with thiourea, released first water endothermically from room temperature to 190 °C, carbonyl sulfide (COS) from 120 to 240 °C in two stages, ammonia (NH3) from 170 to 350 °C in three steps, and organic mater (probably ether and ethylene) between 140 and 230 °C. The evolution of CO2, H2O and SO2, as oxidation products, occurs between 180 and 240 °C, accompanied by exothermic DTA peaks at 190 and 235 °C. Some small mass gain occurs before the following exothermic heat effect at 500 °C, which is probably due to the simultaneous burning out of residual carbonaceous and sulphureous species, and transformation of amorphous titania into anatase. The oxidative process is accompanied by evolution of CO2 and SO2. Anatase, which formed also in the exothermic peak at 500 °C, mainly keeps its structure, since only 10% of rutile formation is detected below or at 800 °C by XRD. Meanwhile, from 500 °C, a final burning off organics is also indicated by continuous CO2 evolution and small exothermic effects.

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). References 1. Yanagisawa , K , Ovenstone , J . Crystallization of anatase from amorphous titania using the hydrothermal technique: effects of starting material and temperature . J Phys Chem B

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Journal of Thermal Analysis and Calorimetry
Authors: Mphilisi M. Mahlambi, Ajay K. Mishra, Shivani B. Mishra, Rui W. Krause, Bhekie B. Mamba, and Ashok M. Raichur

area; however, it has a low photoreactivity because of surface defects [ 32 ]. It was therefore no surprise that the amorphous titania exhibited a large surface area which decreased with an increase in calcination temperatures

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Reaction Kinetics, Mechanisms and Catalysis
Authors: Haiying Wang, Yucheng Yang, Jianhong Wei, Ling Le, Yang Liu, Chunxu Pan, Pengfei Fang, Rui Xiong, and Jing Shi

arrays and transform the amorphous titania to nanocrystalline anatase. Then some of them were annealed in ammonia atmosphere at 500 °C to obtain nitrogen doped TNT arrays. All the reagents of acetone (CH 3 COCH 3 ), ethanol (C 2 H 5 OH), ammonium fluoride

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. Yanagisawa , K , Ovenstone , J . Crystallization of anatase from amorphous titania using the hydrothermal technique: effects of starting material and temperature . J Phys Chem B . 1999 ; 103 : 7781 – 7787 . 10.1021/jp990521c

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