The kaolinite/TiO₂ composite was prepared using thermal hydrolysis of kaolinite/titanyl sulphate suspension and characterized by XRFS, XRPD, SEM and N₂ physical adsorption. Its photocatalytic ...properties were evaluated by photocatalytic reduction of CO₂ by water and compared with commercial TiO₂ photocatalyst Degussa P25. Results showed that the yields of CO₂ photocatalytic reduction products methane and methanol were higher over a kaolinite/TiO₂ composite than over commercial TiO₂ (Degussa P25) in spite of smaller proportion of TiO₂ in the composite. Introducing of TiO₂ nanoparticles into the kaolinite structure caused a decrease of anatase crystallite size. Kaolinite can also change acidobasic properties of catalyst surface, inhibit the recombination of electron–hole pairs and prevent the formation of TiO₂ aggregates in suspension. These facts can contribute to the observed higher photocatalytic efficiency of kaolinite/TiO₂ compared to the commercial TiO₂ photocatalyst.
piNAV L1 is a GPS L1 receiver for position determination of the small satellites at LEO orbits. The receiver was tested by the ReGen software GPS simulator for static and dynamic scenarios. The ...typical horizontal position error for static scenario is 2.5 m (95%). The position errors for dynamic scenarios are affected by the dynamic stress errors.
In the present study, the coupling of adsorption capacity and photocatalytic efficiency of two different industrially produced titania catalysts was investigated and compared. The azo dye Reactive ...Red 195 was selected as a model compound. The tested catalysts, PK-10 and PK-180, exhibited different adsorption capacities due to their significant difference in their specific surface, but both have proven to be effective photocatalysts for photodegradation of the studied dye. PK-10 exhibited strong adsorption of the studied dye due to its high specific surface area, while the second studied catalyst, PK-180, demonstrated negligible adsorption of Reactive Red 195. The effect of the pH, the concentration of the catalyst and the initial concentration of the dye appear to affect the photocatalytic rate. The effect of the presence of humic acids and inorganic ions was also examined, while the contribution of various reactive species was indirectly evaluated through the addition of various scavengers. To evaluate the extent of mineralisation of the studied dye, total organic carbon (TOC) measurements during the experiment were also conducted. Besides total colour removal, evident reduction of TOC was also achieved using both catalysts.
Preparation of nanocomposite kaolinite/TiO2, using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. A variable (kaolin)/(titanyl sulfate) ratio has been used in order to achieve ...the desired TiO2 content in prepared nanocomposites. Calcination of the composites at 600A degree C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO2 composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO2 on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the Material Studio modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution.
Both science and policy require a practical, transmissible, and reproducible procedure for surveillance and monitoring of European habitats, which can produce statistics integrated at the landscape ...level. Over the last 30 years, landscape ecology has developed rapidly, and many studies now require spatial data on habitats. Without rigorous rules, changes from baseline records cannot be separated reliably from background noise. A procedure is described that satisfies these requirements and can provide consistent data for Europe, to support a range of policy initiatives and scientific projects. The methodology is based on classical plant life forms, used in biogeography since the nineteenth century, and on their statistical correlation with the primary environmental gradient. Further categories can therefore be identified for other continents to assist large scale comparisons and modelling. The model has been validated statistically and the recording procedure tested in the field throughout Europe. A total of 130 General Habitat Categories (GHCs) is defined. These are enhanced by recording environmental, site and management qualifiers to enable flexible database interrogation. The same categories are applied to areal, linear and point features to assist recording and subsequent interpretation at the landscape level. The distribution and change of landscape ecological parameters, such as connectivity and fragmentation, can then be derived and their significance interpreted.
The paper summarizes measurements and the Monte Carlo simulations performed to adapt the high purity germanium (HPGe) detectors of the system to the particular tasks of the decommissioning site. The ...work carried out for the installation and adaptation in CIEMAT of the prototype ‘SuperMum’, developed in the framework of the European MetroDecom II project for segregation and declassification of materials is described. The activities related to the validation of the prototype for the specific needs of a real Waste Management Unit are presented.
Monte Carlo models of the SuperMum have been developed at CIEMAT and CMI using different codes and adapted to the geometries used (big-bag containers with the material volume of up to 0.5 m3). Uncertainty budget reporting tailored for the possible deviations between Monte Carlo assumptions and real waste have been analyzed.
Data for several filling levels and activity distributions have been measured with reference sources and a good agreement has been obtained with calculated values.
•New concept of waste segregation and free release measurement systems was validated.•Accurate measurement is facilitated by new certified calibration/testing radionuclide standards.•Uncertainties associated to the measurement of real waste were determined.•Precise measurements reduce the quantity of waste sent to repositories.
The aim of this work is to demonstrate the capability of a Si(Li) detector for the measurement of β spectra, despite the energy absorption in air and in the Be window. A simple source holder fixes ...the source on the symmetry axis at 3mm from the detector window. The β-sources are produced by evaporation on a plastic backing plate. Absorbing materials between the source and the sensitive volume of the detector are 3mm of air, a Be window, 0.1μm Si and 20nm of gold. A model of the detector was created for β spectra simulation using the MCNP 4A code. Experimental spectra of 14C, 147Pm, 204Tl, 90Sr/90Y were compared with simulated spectra.
•Beta spectrometry by a Si(Li) detector.•Model by the MCNP method based on X-ray radiograph.•Comparison of the experimental and computed spectra.•Experimental determination of the endpoint for C-14, Pm-147, Tl-204, and Sr/Y-90.
Nowadays there are lots of methods using three-dimensional or quasi three-dimensional CFD analysis. Unfortunately, this approach is still very demanding, so that quick preliminary design algorithms ...have still its importance, even though simplified analytical model of radial compressor gives less accurate results. Obtained results can be used in later stages of the radial compressor (RC) design, such as definition of spatial impeller geometry and CFD computation. The article presents the influence of input parameters in the radial compressor design algorithm on the efficiency. The assembled mathematical model of RC is derived from the basic laws of continuum mechanics and can be used for a quick assessment of the preliminary design concept of the RC. A sensitivity analysis is performed on input parameters to select parameters that have the dominant effect on the monitored performance indicators. On the basis of the sensitivity analysis, a multicriteria optimization process was assembled to increase the performance parameters.
Comparison of fluorescence intensities of montmorillonite (SAz-1) fully saturated by methylene blue (curve 1) with charge-reduced montmorillonite (RC/SAz-1) loaded with a low amount of methylene blue ...(curve 2).
The intensity of fluorescence of montmorillonites fully saturated by methylene blue (MB) is very poor due to energy dissipation in MB aggregates. A series of reduced charge montmorillonites (RCM) were prepared from Na-homoionic SWy and Ca homoionic SAz with the aim to decrease the MB aggregation. Fine tuning MB adsorption degree by charge reduction and MB concentration enabled controlled production of different dye species from aggregates via dimers to monomers. It was shown that the intensity of the fluorescence of low-loaded MB–RCM complexes is enhanced by several orders of magnitude with respect to dye-saturated original montmorillonites. XRD analyses, molecular modeling, and diffuse reflectance spectroscopy revealed that low MB-loaded RCMs are very probably adsorbed mainly on the external montmorillonite surface as isolated dye molecules. Such a state cannot be achieved in the solid state without very careful tailoring of the host–guest interaction.
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