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Query: UMLS:C0205700 (ash)
 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The TEM-EDS bulk-tissue analysis procedure described involves: (1) low-temperature oxygen-plasma ashing of soft tissue specimens weighing greater than 20 micrograms in aluminum-foil crucibles; (2) the solubilization of the ash in 5 microliter 0.5N HNO3 containing a known quantity of cobalt as an internal, non-interfering reference element; (3) the spraying of the solubilized ash from glass microcapillary tubes onto thin carbon-collodion films mounted on titanium grids; (4) EDS analysis of individual microdroplets approximately 3 micron in diameter; (5) the quantitation of elemental concentrations from the element: cobalt intensity ratio by the "ratio model" technique. This technique was assessed and found to yield linear curves (greater than or equal to 0.999) for elements in 'artificial tissue' standards (concentration range = 5 - 340 mM kg-1 dry weight). The overall reproducibility of the technique is therefore quite good (e.g. error of 4.7% for P and K in 25 analyses) within the range of concentrations expected for most of the major biological elements encountered in vertebrate and invertebrate soft tissues. Absolute accuracy can be improved with quantitative procedures that account for peak-overlapping and escape peak contributions etc., so that the ultimate MDL for sodium may well be of the order of 1 mM kg-1 dry weight. The usefulness of the technique for the provision of basic biochemical information (especially in invertebrate systems which have received but meagre attention) is illustrated: (a) by comparing the calcium content of male and female blood-flukes (Schistosoma mansoni) in mixed-sex and unisexual laboratory infections; and (b) by determining the changes induced by daily injections of the drug Astiban on the element composition of female Schistosoma. We conclude that the technique can represent a useful multi-element detection facility which offers certain pertinent advantages over alternative microchemical techniques, such as atomic absorption spectrophotometry.
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PMID:The electron microprobe analysis of sprayed microdroplets of solubilized biological tissues: a useful preliminary to localization studies. 663 80

The effect of the emissions from large oil shale fuelled power plants and a cement factory in Estonia on the elemental concentration of atmospheric aerosols, deposition, elemental composition of mosses and ecological effects on mosses, lichens and pine trees in the eastern Gulf of Finland region has been studied. In addition to chemical analysis, fly ash, moss and aerosol samples were analysed by a scanning electron microscope with an energy dispersive X-ray spectrometer (SEM/EDS). The massive particulate calcium emissions, approximately 60 kton/year (1992), is clearly observed in the aerosols, deposition and mosses. The calcium deposition is largest next to the Russian border downwind from the power plants and in south-eastern part of Finland. This deposition has decreased due to the application of dust removal systems at the particulate emission sources. At the Virolahti EMEP station approximately 140 km north from the emission sources, elevated elemental atmospheric aerosol concentrations are observed for Al, Ca, Fe, K and Si and during episodes many trace elements, such as As, Br, Mo, Ni, Pb and V. The acidification of the soil is negligible because of the high content of basic cations in the deposition. Visible symptoms on pine trees are negligible. However, in moss samples close to the power plants, up to 25% of the leaf surface was covered by particles. Many epiphytic lichen species do not tolerate basic stemflow and on the other hand most species are also very sensitive for the SO2 content in air. Consequently a large lichen desert is found in an area of 2500 km2 in the vicinity of the power plants with only one out of the investigated 12 species growing.
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PMID:The effect of large anthropogenic particulate emissions on atmospheric aerosols, deposition and bioindicators in the eastern Gulf of Finland region. 1105 48

The purpose of this study is to test the effectiveness of mixing FeSO4 and Fe2(SO4)(3) solutions with municipal solid waste incineration (MSWI) ash at room temperature to prevent heavy metals in treated ash from being dissolved. After conducting toxicity characteristic leaching procedure (TCLP) tests nine times, the accumulation of extracted lead from treated scrubber ash was lower than regulated limits by the sixth test. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) studies of the ash revealed that the mixed solution reacted with the scrubber ash to form Ca4Fe9O17, which coated the surface of ash particles.
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PMID:Stabilization of heavy metals in municipal solid waste incineration ash using mixed ferrous/ferric sulfate solution. 1590 11

The present study focuses on the conversion of heavy metals involved in molten incineration fly ashes to metal sulfides which could be thereafter separated by flotation. The sulfidation treatment was carried out for five molten incineration fly ashes (Fly ash-A to Fly ash-E) by contacting each fly ash with Na(2)S solution for a period of 10 min to 6h. The initial molar ratio of S(2-) to Me(2+) was adjusted to 1.20. The conversion of heavy metals to metal sulfides was evaluated by measuring the S(2-) residual concentrations using an ion selective electrode. The formation of metal sulfides was studied by XRD and SEM-EDS analyses. In the case of Fly ash-A to Fly ash-D, more than 79% of heavy metals of zinc, lead and copper was converted to metal sulfides within the contacting period of 0.5h owing to a fast conversion of metal chlorides to metal sulfides. By contrast, the conversion of about 35% was achieved for Fly ash-E within the same contacting period, which was attributed to a high content of metal oxides. Further, the S(2-) to Me(2+) molar ratio was reduced to 1.00 to minimize Na(2)S consumption and the conversions obtained within the contacting period of 0.5h varied from 76% for Fly ash-D to 91% for Fly ash-C. Finally, soluble salts such as NaCl and KCl were removed during the sulfidation treatment, which brought about a significant enrichment in metals content by a factor varying from 1.5 for Fly ash-D to 4.9 for Fly ash-A.
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PMID:Sulfidation treatment of molten incineration fly ashes with Na2S for zinc, lead and copper resource recovery. 1725 81

The E.U. Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe, Mg, Cu)(Cr, Fe, Al)04(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations.
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PMID:Fate of Cu, Cr, and As during combustion of impregnated wood with and without peat additive. 1794 5

The P-retention in hydrated calcareous ash sediment from oil-shale burning thermal power plants in Estonia was studied. Batch experiments indicate good (up to 65 mg P g(-1)) P-binding capacity of the hydrated oil-shale ash sediment, with a removal effectiveness of 67-85%. The high phosphorus sorption potential of hydrated oil-shale ash is considered to be due to the high content of reactive Ca-minerals, of which ettringite Ca6Al2(SO4)3(OH)12.26H2O and portlandite Ca(OH)2 are the most important. The equilibrium dissolution of ettringite provides free calcium ions that act as stable nuclei for phosphate precipitation. The precipitation mechanism of phosphorus removal in hydrated ash plateau sediment is suggested by Ca-phosphate formation in batch experiments at different P-loadings. Treatment with a P-containing solution causes partial-to-complete dissolution of ettringite and portlandite, and precipitation of Ca-carbonate and Ca-phosphate phases, which was confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM)-EDS studies. Thus, the hydrated oil-shale ash sediment can be considered as a potential filtration material for P removal in constructed wetlands for wastewater treatment.
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PMID:Hydrated calcareous oil-shale ash as potential filter media for phosphorus removal in constructed wetlands. 1795 14

The effects of chlorides (including inorganic chloride NaCl and organic chloride PVC) on Cd emission in MSW (municipal solid waste) incineration was investigated using a simulated tubular furnace and the simulated MSW spiked with heavy metals. The concentrations of heavy metals were measured by ICP-AES after the digesting of samples including bottom ash, fly ash and flue gas according to related USEPA Methods. Heavy metal species in bottom ash and fly ash were identified by X-ray diffraction technique and the spectra of elements distributed and micrographs of bottom ash and fly ash were detected by energy dispersive X-ray system and scanning electron microscope, respectively. The results indicated that the emission of Cd tended to be enhanced with the increasing of chloride content, and 97% Cd partitioned in fly ash after spiked chlorides. However, the content effect of inorganic chloride NaCl and inorganic chloride PVC on Cd emission had no significant difference. The effect of PVC on Cd partitioning was affected by temperature, 80.51% Cd partitioned in fly ash at 550 degrees C and 97.91% Cd partitioned in fly ash at 850 degrees C, when temperature went above the melting point of CdCl2 (568 degrees C), the effect of temperature became less important. The effect of NaCl on Cd partitioning was not affected by temperature, 95.02% Cd partitioned in fly ash at 550 degrees C and 96.58% Cd partitioned at 1 000 degrees C when spiked NaCl. Residence time had no significant effect on Cd partitioning with spiked chlorides. The two different mechanisms of chlorides effects on Cd emission were identified by bottom ash and fly ash analysis using SEM/EDS and XRD technique.
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PMID:[Effects of chlorides on Cd partitioning and speciation in a simulated MSW incinerator]. 1862 22

The waste low-calcium Czech brown coal fly ash represents a considerable environmental burden due to the quantities produced and the potentially high content of leachable heavy metals. The heterogeneous microstucture of the geopolymer M(n) [-(Si-O)(z)-Al-O](n).wH(2)O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ((29)Si, (27)Al, (23)Na), ESEM, EDS, and EBSD. The leaching of heavy metals and the evolution of compressive strength were also monitored. The analysis of raw fly ash identified a number of different morphologies, unequal distribution of elements, Fe-rich rim, high internal porosity, and minor crystalline phases of mullite and quartz. Microcalorimetry revealed exothermic reactions with dependence on the activator alkalinity. The activation energy of the geopolymerization process was determined as 86.2kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the (29)Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO(4) tetrahedra. The (23)Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H(2)O)(n) rather than Na(+), thus causing efflorescence in a moisture-gradient environment. As and Cr(6+) are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn(2+), Cu(2+), Cd(2+), and Cr(3+) are reported.
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PMID:Material and structural characterization of alkali activated low-calcium brown coal fly ash. 1930 4

In this paper, the effects of fluidization velocity, bed temperature and fuel feeding rate on the defluidization time and agglomerate fraction in the fluidized bed combustion of rice straw were studied. The fuel ash, necks in agglomerates and coating layers of bed particles were studied by means of the scanning electron microscope, coupled with energy-dispersive spectroscopy (SEM/EDS). Results showed that the stickiness of bed particles induced by coating layers is the direct reason for bed defluidization. The alkali metals such as K and Na mainly exist in the outer layer of rice straw particles. During combustion the high temperature can cause the alkali species melting and coating the surfaces of ash particles. Consequently, ash particles become sticky and tend to adhere to the surfaces of bed particles. The large-sized ash particles may act as the necks in the formation of agglomerates. The small-sized ash particles may contribute to the formation of coating layers.
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PMID:The role of ash particles in the bed agglomeration during the fluidized bed combustion of rice straw. 1966 17

Bottom ash from a municipal solid waste incinerator on a former contaminated site, the island of Sacca San Biagio (Lagoon of Venice), was examined in order to evaluate levels of pollutants and their potential mobility and availability. Heavy metal concentrations were determined and the actual contamination of the site was compared with national legislation on polluted sites. The site was mainly contaminated by zinc, copper and lead. Physico-chemical characterization of bottom ash was carried out by SEM (Scanning Electron Microscopy) with micro-analysis by EDS (Energy Dispersive X-ray Spectroscopy) and XRD (X-ray Diffractometry), for information on newly formed minerals. SEM-EDS analysis revealed the presence of particles, compounds and clusters containing heavy metals and, in particular, the presence of barium sulfate, which was assumed to be a site-specific compound. Similarities between bottom ash and atmospheric PM10 collected on the adjacent island of Sacca Fisola were studied and a risk of aerodispersion of the fine fraction of ash was assumed. Lastly, in order to evaluate the potentially available fraction of metals (non-residual fraction) and the directly exchangeable fraction, two single extraction procedures with HCl and citric acid were carried out, respectively. Results showed a relatively low concentration of readily phyto-available metals, as well as the high concentrations found for some heavy metals (Cu, Pb, Zn) in the potentially mobilizable fraction.
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PMID:Characterization of a former dump site in the Lagoon of Venice contaminated by municipal solid waste incinerator bottom ash, and estimation of possible environmental risk. 1969 69


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