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, polyamidoamine (PAMAM)–Fe 2 O 3 nanocomposites have been developed for applications in nanomedicine [ 16 – 18 ]. Strable et al. [ 7 ] and Shi et al. [ 19 ] synthesized carboxyl-terminated PAMAM dendrimers–iron oxide nanocomposites by a template technique for

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Phase equilibria in subsolidus area in the ZnO-V2O5-Fe2O3 system have been investigated over the whole concentration range of the oxides. The components of this system form two compounds: Zn2FeV3O11 and Zn3Fe4(VO4)6. A solidus area projection onto the component concentration triangle plane of the ZnO-V2O5-Fe2O3 system has been constructed using DTA and XRD methods. 11 subsidiary subsystems can be distinguished in this system. Melting temperatures of mixtures of solid phases coexisting at equilibrium in each of subsidiary subsystems were determined.

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in a non-conducting polymer matrix [ 14 ]. Looking into the wide application of these, in this study, we have prepared polycarbonate nanocomposite films by dispersing CuO and γ-Fe 2 O 3 material in the polycarbonate matrix through solvent casting

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Introduction It is known that the components of the ternary systems MO–V 2 O 5 –Fe 2 O 3 as well as the compounds existing in their lateral systems catalyze a lot of chemical reactions [ 1 – 3 ]. Therefore, it can be expected

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Abstract  

Spindle-shaped α-FeOOH particles were synthesized using the chemical coprecipitation method in Fe(CO3)x(OH)2(−x) suspensions system by adding metallic ions. The spindle-shaped γ-Fe2O3 particles were obtained by dehydration of α-FeOOH, and subsequent reduction and oxidation. Its thermal stability was investigated by differential thermal analysis (DTA). It was found that the transition temperature of γ-Fe2O3→α-Fe2O3 of samples doped with metallic ions is higher than that of the pure γ-Fe2O3 and increasing with increase of the size of the metallic ions, and γ-Fe2O3 by doping with two or more different metallic ions together has even higher thermal stability. The origin of the improved thermal stability was discussed. Additionally, the magnetic properties of γ-Fe2O3 were measured.

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A novel combustion method of employing poly(ethylene glycol) with the precursor in a fixed ratio for the synthesis of ultrafine γ-Fe2O3 through a self-propagating combustion synthesis is reported. Four different precursors viz. ferrous hydroxide, ferrous oxalate dihydrate, ferric 8-hydroxyquinoline and ferric acetylacetonate are employed in this study for the conversion of these precursors to ultrafine g-Fe2O3 particles. The as synthesized γ-Fe2O3 samples are characterized by XRD, SEM and thermal techniques. A case study for the synthesis of γ-Fe2O3 employing ferric acetyl acetonate as precursor is reported. The importance of employing thermal analysis techniques in understanding the combustion synthesis is envisaged.

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Radioactive as well as inactive cobalt precipitated from an aqueous solution onto the surface of -Fe2O3 was investigated by the Mössbauer spectroscopy of57Fe. The experiment performed with the57Co-doped sample showed that some of the cobalt atoms diffused into the -Fe2O3 lattice owing to 1 h of heat treatment carried out at 300 °C.

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Summary  

The adsorption of 99Tc on the adsorbers Fe, Fe2O3 and Fe3O4 was studied by batch experiments under aerobic and anoxic conditions. The effects of pH and CO3 2- concentration of the simulated ground water on the adsorption ratios were also investigated, and the valences of Tc in solution after the adsorption equilibrium were studied by solvent extraction. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 were determined. Experimental results have shown that the adsorption ratio of Tc on Fe decreases with the increase of pH in the range of 5-12 and increases with the decrease of the CO3 2- concentration in the range of 10-8M-10-2M. Under aerobic conditions, the adsorption ratios of 99Tc on Fe2O3 and Fe3O4 were not influenced by pH and CO3 2-concentration. When Fe was used as adsorbent, Tc existed mainly in the form of Tc(IV) after equilibrium and in the form of Tc(VII) when the adsorbent was Fe2O3 or Fe3O4 under aerobic conditions. The adsorption ratios of Tc on Fe, Fe2O3 and Fe3O4 decreased with the increase of pH in the range of 5-12 and increased with the decrease of the CO3 2- concentration in the range of 10-8M-10-2M under anoxic conditions. Tc existed mainly in the form of Tc(IV) after equilibrium when Fe, Fe2O3 and Fe3O4 was the adsorbent under anoxic conditions. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 are fairly in agreement with the Freundlich’s equation under both aerobic and anoxic conditions.

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X-ray, magnetic and differential thermal analysis and thermogravimetric (DTA-TG) measurements of Fe2O3 nanoparticles surrounded by amorphous SiO2were carried out. The mass loss above 370 K could be attributed to the dehydration. The broadened exothermic peak around 900 K was observed by the DTA analysis. Considering the results of the X-ray and magnetic analyses, this anomaly was interpreted as due to the g- to a-transition in the present Fe2O3nanoparticle system. The broadness of the peak and thus the gradual progress of the transformation would be attributed to the stress caused by the amorphous SiO2 network surrounding extremely small particles.

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Reaction Kinetics, Mechanisms and Catalysis
Authors: Dimitar Klissurski, Ivan Mitov, Krasimir Ivanov, Georgi Tyuliev, Dimitar Dimitrov, Kristina Chakarova, and Ivan Uzunov

Abstract  

The heterogeneous catalytic oxidation of methanol on Au/Fe2O3 catalysts in the temperature range 50–300 °C has been studied. A high activity of the catalyst with respect to the complete oxidation of methanol to carbon dioxide has been observed. The degree of conversion is higher than 50% at 100 °C and almost 100% at 150 °C.

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