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Summary  

The Am(III) adsorption isotherms on natural hematite, on a red earth and on three kinds of treated red earth samples were determined and compared. The treatment was performed to remove iron oxides, organic matter (OM) and both. The batch technique and aqueous Am(III) solutions with molarities less than 3 . 10-9 mol/l were used. A very high adsorbability of Am(III) on hematite was found, and in order to decrease the adsorption percentage, stable Eu3+ as a hold back carrier was added to the aqueous solution. All the isotherms were found to be linear. The strong effects of pH, ionic strength and fulvic acid (FA) on the Am(III) adsorption on natural hematite were demonstrated. A positive contribution of OM and an unexpectedly high negative influence of iron oxides on the Am(III) adsorption by the untreated red earth were found too. The average distribution coefficients of Am(III) adsorption on natural hematite, on red earth and on three kinds of treated red earth samples were determined, respectively, from these linear isotherms. The very high adsorbability of Am(III) on hematite and the very strong negative influence of iron oxides on the Am(III) adsorption on untreated red earth were distinctly demonstrated as well. It appears that the adsorbability of composed natural materials cannot be predicted from the adsorbabilities of each of the mineral components alone, due to possible interactions between the mineral components and the different characteristics of the composite.

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Knowledge of the distribution and sorption characteristics of trace metals in soils is essential because of their importance both from agricultural and environmental point of view. In this paper, an overview will be provided on the relationship between the behavior and sorption properties of Cu and Pb as well as major soil characteristics, based on the results obtained by several independent research projects carried out on this field at the Institute for Geological and Geochemical Research over the last 15 years. These projects were accomplished using methods with different approaches, e.g. studying metal characteristics by total metal content, selective chemical extractions and batch sorption experiments.Our results show that both metals can be found in soils, primarily in the form of phases highly resistant to weathering. However, if they are mobilized, they are easily and strongly immobilized by soils rich in organic matter, with higher affinity for Cu than for Pb. In acid soils, on the other hand, the leaching of Cu is expected to be higher from such horizons when compared to Pb, especially when iron oxides, which immobilize Pb preferentially, are also present in these horizons. In mineral horizons the close association of Pb and iron oxides can be still expected, whereas Cu prefers to be bound both by clay minerals and iron oxides. In alkaline soils, however, precipitation of both metals as carbonates is a general feature. Our results obtained through different approaches presented in this paper were found to be effectively complementary to each other, providing a much deeper insight into soil-metal interaction than when they are used independently.

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Abstract  

Mössbauer spectroscopy, X-ray diffractometry and microprobe analysis were used to study electrodeposited Fe−Ni−Cr (40–50% Fe, 40–47% Ni, 3–5% Cr) alloys isothermally aged at 500°C from 5 minutes to 100 hours in an inert argon gas atmosphere. The main phase of the as-deposited samples exhibits ferromagnetic microcrystalline behavior, whereas the thermally prepared samples of same composition are always paramagnetic. The dominant effect of ageing is an oxidation process which resulted in the formation of hematite and magnetite iron oxides in considerable amounts and which are attributable to the presence of oxygen inclusions in the as-electrodeposited samples.

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Several ornaments named tezcacuitlapilli (coccyx-mirrors) are described and chemical analyses of raw materials (slate and pigments) were carried out by neutron activation, X-ray diffraction, scanning electron microscopy and radiography. Elemental and statistical analyses revealed that three different kinds of slate were used in their manufacture. The white pigment contains gypsum while ochre, yellow and red pigments contain iron oxide. These ornaments were identified as coming from the Cave of the Sun Pyramid of Teotihuacan. An attempt was undertaken to reconstruct the contexts of their manufacture and symbolic interpretation.

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In the present study, ethylbenzene dehydrogenation to styrene monomer over a potassium-promoted iron oxide catalyst in radial fixed bed reactor was simulated. The pseudo-heterogeneous model was employed to predict ethylbenzene conversion and selectivity of styrene monomer, toluene, and benzene. The simulation results showed that deactivation of catalysts causes reduction in the reaction zone; therefore, the ethylbenzene conversion decreases. It is proposed that, for compensating the conversion reduction, the feed temperature is increased 1 °C per 5 cm of deactivated length. Simulation results are in good agreement with the experimental data obtained from real plant.

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Abstract  

As evident from archaeological excavation, ochre was widely used for ceremonial, mortuary, and other purposes around the world. However, the ancient meaning and procurement practices of ochre are not well understood. This study examines the variation in the major, minor and trace element patterns of ochre from iron oxide sources in southeastern Missouri to better understand the differences that may occur within and between sources. Samples were analyzed by instrumental neutron activation analysis (INAA), X-ray fluorescence spectroscopy (XRF), and the data were interpreted by Pearson’s linear correlation and multivariate analysis. The data indicate geochemical trends in ochre that satisfy the provenance postulate.

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Abstract  

The Mössbauer parameters were determined on a series of catalyst mixtures of iron and zinc oxides with variable quantities of zinc. From these results, a change in the crystal structure of the iron oxide when introducing zinc into the samples was observed. The corundum structure of the -Fe2O3 phase was transformed into the spinel type of zinc ferrite when zinc oxide was present in any quantity. By means of these parameters a strong electronic interaction between the zinc ferrite and the zinc oxide present in excess was evident. The catalysts were analyzed using X-ray fluorescence /XRF/ and X-ray diffraction /XRD/.

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Abstract  

Reactions in aqueous-alcoholic solution between diphenyl-4-amine barium sulphonate (Ba-DAS—anionic surfactant) and the hydrated sulphates of Fe(III) and Fe(II) ions and their use to ovtain iron oxides are described here. The formation of Fe(II) complexes was reached by using an excess of Ba-DAS, in absence of light under inert atmosphere. The complexes achieved Fe2[(C12H10NO3S)4]·9H2O and Fe3[(C12H10NO3S)6]·12H2O were characterized by TG/DTG and IR, UV-VIS and 57Fe-Mössbauer analyses.

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Abstract  

Depth profiles potassium and its isotope ratio (40K/K) were investigated in several forest soils from different geological and climatic backgrounds. The ratio was found not to be constant (0.0117%) but varied appreciably from 0.0085% to 0.0167% among different soils. Possible factors affecting variability of 40K/K values were considered by a multivariate factor analysis which suggested that aqueous parameters like humidity and pH might be a controlling factor in the surface soils. The amount (and probably chemical forms) of iron oxide may be another one influencing 40K/K values in mineral components at deeper portions.

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Abstract  

For an investigation of the ancient iron manufacturing technique, a modern simulation experiment was carried out. The smelting furnaces were built with clay. Charcoal and raw materials were installed from the top of the furnace. Magnetite was used as the raw material. In the furnace, iron oxide was reduced to metallic iron. The reduction reaction was mainly controlled by temperature and oxygen fugacity in the furnace. In order to investigate the possibility for the estimation of these parameters, 57Fe Mössbauer spectra were recorded of the furnace wall at room temperature.

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