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The phase changes in the solid state in E AlMgSi alloy are discussed. The dissolution and precipitation processes are investigated by DTA, and the results can be applied to control the technological parameters of dissolution heat treatments.

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A pilot plant was developed for the reclamation and reuse of secondary effluent from a sewage treatment plant. The plant system consists of sand filtration, gamma-irradiation, ozonation and ion-exchange. Gamma-irradiation showed effective organic contaminant decomposition and this resulted in the reduction of 5-day biochemical oxygen demand (BOD5), color, chemical oxygen demand (CODCr) and total organic carbon (TOC). Ion-exchange significantly removed inorganic ions, and thus reduced total nitrogen (TN) and total phosphorus (TP). The average reduction in color, CODCr, BOD5, TOC, TN and TP, which was obtained after 12 operations, was 64, 52, 67, 61, 95 and 92%, respectively. Irrespective of applied radiation dose, the treated water fully satisfied the quality requirements of household water that can be used for all home uses except for drinking and human contact uses.

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The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has been studied using mainly57Fe Mössbauer spectroscopy. -Fe2O3 nanoparticles appear as the primary Fe3+ phase in Mössbauer spectra of olivine samples heated at 600-900 °C. These nanoparticles are thermally unstable and they are transformed to -Fe2O3 with the increase of heating time. Another transformation mechanism of iron related with the complete decomposition of olivine structure has been observed at temperatures of 1000 °C and higher. The mixed oxide MgFe2O4 with the spinel structure and enstatite MgSiO3 were identified as iron-bearing decomposition products.

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Mg-Al L(ayered) D(ouble) H(ydroxide) was prepared and its thermal behaviour was characterized by thermoanalytical methods (TG, DTG, DTA), 27Al M(agic) A(ngle) S(pinning) NMR spectroscopy, X-ray diffractometry (XRD) and S(canning) E(lectron) M(icroscopy). Heat treatment destroyed the layered structure, which could only be partially reconstituted by rehydration. On calcination mixed oxide with the predominance of basic sites were formed. Pillaring the LDH with Fe(CN)6 4- anions was also performed. The material was characterized by XRD and BET measurements. Heat stability of the pillared substance was investigated, too. Pillaring proved to be successful, however, decreased heat resistance was found in the intercalated material relative to the guest LDH.

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A rapid validated thin-layer chromatography (TLC)‒densitometric method has been developed for the simultaneous determination of 3 co-formulated drugs used for common cold and cough treatment. The studied drugs are paracetamol, pseudoephedrine, and chlorpheniramine maleate. The separation was achieved using silica gel 60 F254 plates and the developing system of methanol‒ toluene‒acetic acid (44:16:1, v/v). Densitometry scanning was performed at 254 nm. The method was validated as per the International Conference on Harmonization (ICH) guidelines and was successfully applied for the analysis of pharmaceutical preparation containing the cited ternary mixture without interference from excipients. There is no previously published TLC–densitometric method for the determination of the previously mentioned ternary mixture. The suggested method is rapid and of low cost, so it can be used for quality control analysis.

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The presence of toxic heavy elements such as arsenic, cadmium and mercury in industrial wastewater and waterways is a serious pollution problem. The treatment of such contaminated water by conventional techniques, which often includes an ion-exchange or similar step, is expensive. This paper examines the use of natural materials such as hair, and certain plants, which are inexpensive, for the absorption and hence the clean up of heavy elements from polluted water. Our results show that these natural materials concentrate the heavy elements, in certain cases, to the extent of up to 500 fold or even better. The contact time required is of the order of several hours. The capacities of absorption vary from about 1 g/kg to about 5 g/kg for mercury, and are lower for arsenic and cadmium. The results show that with hair, nearly 10,000 liters of mercury contaminated water, a typical daily output from a 100 ton chlor-alkali plant, can be treated with about 1/2 kg of hair valued at about 25 cents. This makes the process extremely cost-effective compared to the conventional processes now in use.

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This report describes the environmental sample treatment techniques for14C measurement with liquid scintillation counter. The groundwater sample of about 80 liters was collected from well and inorganic carbon was removed by acidification and recirculated gas stripping with the extraction efficiency of more than 98%. The biological samples were freeze-dried and combusted to carbon dioxide in high pressure combustion unit with a combustion efficiency of nearly 99%. The14CO2 in the stack effluents was collected by an air bubbler with a collection efficiency of more than 99% for a sampling time of two weeks. Sampling of14C in reduced form also has been done by passing the gases through a tube furnace with Pt/Al and Pd/Al catalyst. Active and passive sampling methods for atmospheric14C measurements were compared in detail, and it could be concluded that the uncertainty associated with passive sampling method was quite acceptable for environmental monitoring. The CO2 trapped in NaOH was precipitated as BaCO3, and subsequently reconverted to CO2 for environmental samples and transferred to Carbo-Sorb ETM for liquid scintillation counting. In case higher precision is the deciding factor, benzene synthesis would be employed with home-made benzene synthesizer.

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Perovskite oxides of composition (Sr1-xCax)(Fe0.5Co0.5)O3- were investigated for CO2 absorption properties and were proved to be useful as materials for CO2 absorption in the temperature range from 550 to 850 °C. The absorption rate of CO2 increased with Ca doping. The mechanical treatment of perovskite oxides for several minutes, especially for the oxides containing a small amount of Ca, was found to be effective for activating the oxides for CO2 absorption and for reducing the starting temperature of CO2 absorption by about 80 °C. However, it was not less effective to treat the oxides for a long time. The site distortion due to Sr and Ca ions at site A and the mixed valence states at site B were confirmed to be effective for CO2 absorption at high temperatures. During the absorption of CO2, a spinel compound was formed according to the following reaction: 2(Sr,Ca)(Fe,Co)O2.5 + CO2 (Sr,Ca)CO3 + (Sr,Ca)(Fe,Co)2O4.

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Formation and filtration characteristics of solids generated in a high level liquid waste treatment process

II. Filtration characteristics of solids formed in simulated high level liquid waste

Journal of Radioanalytical and Nuclear Chemistry
Authors: Y. Kondo and M. Kubota

Abstract  

The filtration characteristics of solids generated in a simulated high level liquid waste (HLLW) were experimentally examined, when the simulated HLLW was processed according to the ordinary way of actual HLLW treatment process. The filtration characteristics of solids depended on the particle size. The phosphomolybdic acid, which was very fine particle with about 0.1 m diameter, made slurry a difficult-to-filter slurry, if the phosphomolybdic acid content (wt%) to the whole solids in a slurry exceeded 50 wt%. On the contrary, the zirconium compounds (zirconium molybdate and zirconium telluride) had positive effect on filtration characteristics because of their relatively large particle size of about 3 to 5 m. When the zirconium compounds content was above 50 wt%, slurry became a easy-to-filter slurry. A centrifugal sedimentation was discussed as a solid/liquid separation technique for very fine particles such as phosphomolybdic acid. The theoretical feed flow rate corresponded to 0.1 m diameter particles was about 20 l/h at the centrifugal acceleration of about 8000 G.

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Two kinds of feldspars, such as microcline and albite, were irradiated with g-rays of 250 Gy in 77 K and followed by ESR-measurements at 77 K. First ESR-spectra showed an Al-Oh+ center peak at a centeral part and hydrogen radical peaks having hyperfine (HF) splitting width of 50.2 mT. Second ESR-spectra measured after warming up to room temperature once showed eleven absorption peaks owing to an Al-Oh+-Al center, together with complete disappearance of H0-radicals. The Al-Oh+-Al signals in ESR-spectra showed similar dose response curves in both feldspars, giving almost linear relationships up to several hundred Gy and saturation behavior beyond 1 kGy. Thermal treatment of the feldspars induced an interesting appearance of two new hydrogen radicals in the ESR spectrum, which possess broader HF splitting in the ESR-spectra and relatively stable property at room temperature. The correlation of Al-Oh+-Al centers and the BTL intensities around 180 °C peak showed linear dependency. As a result, it is concluded that the Al-Oh+-Al centers should be main BTL-luminescence centers around the 180 °C peak in the feldspars.

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