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This paper presents the results of our recent investigation focused on the preparation and possible photocatalytic application of iron doped TiO2 coatings formed by plasma electrolytic oxidation of high purity titanium in electrolyte containing FeSO4. The morphology, phase and elemental composition, and absorption band of the coatings were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The photocatalytic activity of coatings was evaluated by measuring the degradation of methyl orange under simulated sunlight conditions. It was found that the addition of iron precursor to electrolyte solution improves the photocatalytic properties of obtained coatings with respect to pure TiO2 coating. The incorporation of iron in TiO2 lattice was identified as the main factor affecting the increase of photocatalytic activity. The highest photocatalytic activity was observed when coatings were processed for 2 min with addition of 1 g/L FeSO4 to electrolyte. [ABSTRACT FROM AUTHOR]

In this study, WO3 doped TiO2 powders were synthesized via sol-gel method combined with a hydrothermal process. The effect of sintering temperature on mesoporous structure and catalytic activities of these powders were investigated. The physical analysis via X-ray diffraction indicates that prepared samples are a mixture of anatase and rutile TiO2 phases. X-ray peak analysis is used to evaluate the crystallite size and lattice strain by the Williamson-Hall analysis. Considering all the reflections of the anatase phase the lattice strain ranging from c = 9.505 to c = 9.548 is calculated, suggesting that microstrain decreases when calcination temperature increases. N2 adsorption-desorption analysis shows that the surface area and pore volume decrease with increasing temperature and that WOx-TiO2 powders primarily consist of mesopores. Sintering temperature induced a change in textural properties causing a systematic shift towards larger mesopores. Simultaneously, photoactivity in decolorization of methyl orange increases with increasing calcination temperature up to 700°C, followed by significant decrease with its further increase. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172022, Grant no. 172026, Grant no. 172015, Grant no. 172018, Grant no. 172001 and Grant no. III 45001]

Ethylene oxide (EtO) is an organic compound, which is used as starting material in the production of polymers and as sterilizing agent for thermolabile materials. Although ethylene oxide is not common as an organic pollutant, its removal from numerous emission sources (e.g. ethylene oxide production plants or food and pharmaceutical sterilizing units) is of the crucial importance because of its mutagenic, teratogenic and cancerogenic effect on human health. The objective of this paper is the experimental investigation of ethylene oxide (EtO) absorption in diluted aqueous solution of sulfuric acid in order to evaluate the applicability of this procedure as well as to obtain project parameters for industrial plant realization. It was found that absorption is suitable as the fist step in the purification treatment of high EtO concentrations in the emission gases. According to the literature data, the basic parameter that defines the scrubber efficiency is the contact time, i.e. the ratio of packing height in scrubber and velocity of gas mixture. To investigate the characteristics of wet treatment in a broad range of contact time, part of experimental studies were conducted in the system with two and with three scrubbers in series. The obtained experimental results show that the high degree of EtO removal can be achieved (>98%) when the contact time is sufficiently long (about 25 s). The process is effective until the concentration of formed glycol in the solution reaches value of about 20%. The process is safe and there is no danger of ignition and explosion of air and EtO mixture, although at the entrance to the scrubber EtO concentrations are significantly above the lower explosive limit.

The dynamics of ethylene oxide sorption and desorption on Al2O3 sorbent were investigated. The investigations of ethylene oxide sorption on Al2O3 show that significant sorption appeared above 125°C. The removal of sorbed ethylene oxide from Al2O3 was achieved by continuous increasing of the temperature up to 450°C in air stream. The analysis of desorbed products show that 90% of adsorbed ethylene oxide is converted to CO2 and the rest consists of the three derivatives of ethylene oxide. The exact composition of desorbed organic products will be determined in further investigation. The desorption temperature profiles point out the presence of two exothermic picks, as was confirmed by detection of CO2 and derivates of ethylene oxide at these temperatures. Investigation of textural characteristics and thermal stability of Al2O3 sorbent show that there are no changes of any characteristics of Al2O3 in sorption/desorption operating temperatures regimes. Only at 700°C the specific surface area of Al2O3 decreases of about 10%. This indicates that the investigated Al2O3 is convenient material for removal of ethylene oxide by sorption.

The removal of volatile organic compounds (VOCs) from numerous emission sources is of crucial importance due to more rigorous demands on air quality. Different technologies can be used to treat the VOCs from effluent gases: absorption, physical adsorption, open flame combustion, thermal and catalytic incineration. Their appropriateness for the specific process depends on several factors such as efficiency, energy consumption, secondary pollution, capital investments etc. The distinctive features of the catalytic combustion are high efficiency and selectivity toward be­nign products, low energy consumption and absence of secondary polluti­on. The supported noble catalysts are widely used for catalytic incineration due to their low ignition temperatures and high thermal and chemical stability. In our combined system adsorption and desorption are applied in the spouted bed with draft tube (SBDT) unit. The annular zone, loaded with sorbent, was divided in adsorption and desorption section. Draft tube enabled sorbent recirculation between sections. Combustion of desorbed gases to CO2 and water vapor are realized in additive catalytic reactor. This integrated device provided low concentrations VOCs removal with reduced energy consumption. Experiments were conducted on a pilot unit of 220 m3/h nominal capacity. The sorbent was activated carbon, type K81/B - Trayal Corporation, Krusevac. A sphere shaped commercial Pt/Al2O3 catalyst with "egg-shell" macro-distribution was used for the investigation of xylene deep oxidation. Within this paper the investigations of removal of xylene vapors, a typical pollutant in production of liquid pesticides, in combined adsorber/desorber/catalytic reactor system is presented.

This article shows the changes in the populations of Croatian and Serbian ethnic affiliation in Croatia based on population censuses of 1991 and 2001. In the last intercensal period (1991-2001), methodological definitions of resident population changed significantly, Croatia's administrative-territorial borders changed and a war occurred (1991-1995), all of which influenced the demographical situation of Croatia. It is of special importance that the term 'ethnic affiliation' is significantly unstable and unpredictable and highly influenced by both subjective and external influences, which make its analysis even more difficult. By establishing a connection between the old (1991) and the new (2001) names of settlements, the authors demonstrated the changes in the share of ethnic Croats and Serbs in the total population of towns and municipalities in Croatia in the observed intercensal period. Both the demographic and the ethnic profile of Croatia changed in the period of 1991-2001. The total population of Croatia, as well as the population of ethnic Serbs, decreased in this period, while the population of ethnic Croats increased. Since Croatia had a negative natural increase in the observed period, this increase is attributed to migrations and changes in declarations of ethnic affiliation. While the share of ethnic Serbs decreased significantly (from 12,2% in 1991 to 4,5% in 2001), their territorial distribution remained practically the same. .

A prototype of a solid fuel thermo-accumulating furnace has been developed. In order to achieve a higher combustion efficiency, a Pt/Al2O3 catalyst in the form of 3 ± 0.3 mm spheres was applied, which enabled further combustion of flue gases within the furnace. Experimental investigation of the influence of the catalyst on the conversion of CO has been done for different operation regimes and positions of the catalyst. Paper presents selected results regarding CO emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position to CO emission reduction. The microstructure of the catalyst beads, characterized by selective chemisorption of CO, has shown the decrease of the number of Pt sites as a consequence of blockage by coke deposits formed during the combustion of solid fuel. .

The removal of ethylene oxide (EtO) in a combined system adsorber desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the "hot" section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator while the "cold" section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two sections by use of a draft tube riser. The Computational Fluid Dynamics (CFD) program package FLUENT was used for simulations of the operation of the combined system. In addition, a one-dimensional numerical model for the operation of the packed bed reactor was compared with the corresponding FLUENT calculations. The results of the FLUENT simulations are in very good agreement with the experimental observations, as well as with the results of the one-dimensional numerical simulations.

We have measured highly visible Aharonov-Bohm (AB) oscillations in a ring structure defined by local anodic oxidation on a p-type GaAs heterostructure with strong spin-orbit interactions. Clear beating patterns observed in the raw data can be interpreted in terms of a spin geometric phase. Besides h/e oscillations, we resolve the contributions from the second harmonic of AB oscillations and also find a beating in these h/2e oscillations. A resistance minimum at B=0 T, present in all gate configurations, is the signature of destructive interference of the spins propagating along time-reversed paths.