Search Results
Abstract
A radiochemical procedure for simultaneous determination of lead (203Pb), thallium (202TI) and cadmium (115Cd
115mIn) after fast neutron activation, based on ion-exchange separation from bromide medium and additional purification steps for Pb and Tl is described. Radioactive tracers210Pb and109Cd were used for determination of the chemical yields of Pb and Cd; for Tl it was determined gravimetrically. Two standard reference materials, BCR CRM No. 146 Sewage Sludge and NIST SRM 1633a Coal Fly Ash were analyzed and satisfactory agreement with certified values was obtained.
Abstract
We have examined the leachability of the toxic elements cadmium, arsenic, mercury, and selenium from solid wastes. The solid wastes studied are municipal incinerator ash, coal fly ash, hospital incinerator ash, raw sewage sludge, sewage incinerator bottom ash, and sewage incinerator lagoon ash (which is a combination of bottom and fly ashes). Cadmium displayed the greatest leachability in all waste types, with 76% leached from the municipal refuse incinerator ash. Although the sources of elements in the wastes are diverse, the leachability and hence the bioavailability in the incinerator ash appears mainly determined by the volatility of the element.
cement with different fine-grained additives such as waste materials (e.g. silica fume [ 1 , 2 ], fly ash [ 1 – 3 ], slag [ 4 ], spent aluminosilicate [ 5 ]) as well as other types of cements (e.g. Portland cement [ 6 , 7 ]) have been undertaken. In
Abstract
Oil shale ashes from the PAMA demonstration power plant in the Negev region of Israel are produced by fluidized bed combustion (700–850C) under short residence time. The FED is organic-rich calcareous raw material rich in carbonate rather than clays. Thus it is important to ascertain whether the calcite in the ashes is original natural calcite from the raw material or the product of recarbonation of lime. Three groups of ashes from the power plant, Ash Cooler (AC), Fly Ash (FAS) and Boiler Bank (BB) were examined using XRD, FT-IR, SEM and isotope analysis methods. The recarbonated calcite is distinguished from the natural original by smaller crystal size, lower degree of crystallinity and the presence of impurities. High negative δ13C values in oil shale ashes are explained by assuming recarbonation of lime with CO2 originating from the combustion of the organic matter of the raw oil shale. Fly Ash, FAS, and BB, produced from organically-rich FED, contain more recarbonated calcite than bottom ash, AC. This observation can be explained by the larger grains of the AC, which do not reach the highest temperature area, and thus most of the original calcite does not decompose.
Summary
A simple sample decomposition and laser fluorimetric determination of uranium at trace level is reported in certain refractory minerals, like ilmenite, rutile, zircon and monazite; environmental samples viz. soil and sediments; industrial waste materials, such as, coal fly ash and red mud. Ilmenite sample is decomposed by heating with ammonium fluoride. Rutile, zircon and monazite minerals are decomposed by fusion using a mixture of potassium bifluoride and sodium fluoride. Environmental and industrial waste materials are brought into solution by treating with a mixture of hydrofluoric and nitric acids. The laser induced fluorimetric determination of uranium is carried out directly in rutile, zircon and in monazite minerals and after separation in other samples. The determination limit was 1 μg . g-1 for ilmenite, soil, sediment, coal fly ash and red mud samples, and it is 5 μg . g-1 for rutile, zircon and monazite. The method is also developed for the optical fluorimetric determination of uranium (determination limit 10 μg . g-1) in ilmenite, rutile, zircon and monazite minerals. The methods are simple, accurate, and precise and they require small quantity of sample and can be applied for the routine analysis.
Abstract
Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylene
toluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.
calcium fly ash geopolymer concrete with alccofine , Advances in Concrete Construction , Vol. 5 , No. 1 , 2017 , pp. 17 – 29 . [2] Ondova M
Abstract
USGS BCR-1 and G-2, NBS 1633a Coal Fly-Ash and a 7-element synthetic standard for biological material have been analysed in this work by reactor NAA, using the k0-standardization method. The analyses were performed independently in the analytical laboratories of the Institute for Nuclear Sciences (INW), Gent, and the Central Research Institute for Physics (KFKI), Budapest. This procedure allowed not only a comparison with the specified data or with other published values, but enabled a check of the consistency of our own results obtained in largely different experimental circumstances. As concluded the k0-standardization method combines general versatility (with respect to irradiation and counting conditions) with good accuracy, while keeping the experimental work as simple as possible. Since the k0 method is a computer-oriented technique, a FORTRAN IV program was designed and applied on a VAX 11/780 machine.
Abstract
Concentrations of 35 elements in Chinese Standard Rocks (GSR-1 to GSR-3) and Soils (GSS-1 to GSS-8) have been measured with INAA using the SLOWPOKE reactor. At the same time, the U. S. NBS reference standards: SRM-1632a (Bituminous Coal), SRM-1633a (Coal Fly Ash) and SRM-1646 (Estuarine Sediment) were also analyzed in order to cross-check the accuracy of this method. The results obtained indicate that the reproducibility of the method is satisfactory for most of the elements, namely the precision in general, is better than ±10%. Comparison of our values for NBS SRM-1632a, 1633a and 1646 with the certified values of NBS or with values cited in the literature indicates good agreement. The results were found to be accurate within ±10% error of the established results.
Abstract
A review is presented on the use of neutron activation analysis (NAA) for the analyses of coal, oil shale, tar sands and petroleum. Fast NAA has been widely used for the determination of oxygen, and to a limited extent, of other elements such as nitrogen and silicon. Reactor NAA followed by instrumental counting, and in specific cases, after radiochemical separations is discussed. Thermal and epithermal neutrons are both used. Limited use of the252Cf source has been made in fuel analysis. A complementary technique to NAA is the photon-activation analysis with linear accelerator. It can determine over thirty elements, many of them not possible to do by NAA. Round-robin analyses of standard coal, fly ash, or oil shale samples indicate nuclear activation methods are comparable in accuracy and precision to X-ray fluorescence or atomic spectrometric methods for most elements.
