Academic literature on the topic 'Zn solid phase speciation'
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Journal articles on the topic "Zn solid phase speciation"
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Barrett, J. E. S., K. G. Taylor, K. A. Hudson-Edwards, and J. M. Charnock. "Solid-phase speciation of Zn in road dust sediment." Mineralogical Magazine 75, no. 5 (October 2011): 2611–29. http://dx.doi.org/10.1180/minmag.2011.075.5.2611.
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AbstractX-ray absorption spectroscopy, scanning electron microscopy (SEM) and X-ray diffractometry (XRD) have been used to study the solid-phase speciation of Zn in urban road dust sediments (RDS) in Manchester, UK. X-ray absorption near-edge structure (XANES) analysis using linear combination modelling suggest that the soluble species Zn(NO3)2·6H2O and ZnCl2 represent 70—83%, and Zn-sorbed goethite 17—30%, of the Zn species present. The presence of goethite is not corroborated by extended X-ray absorption fine structure (EXAFS) modelled first shell scattering Zn—O distances of 2.01—2.03 Å, but this may be due to distortion of the Zn octahedra on the goethite surface, or the existence of Zn-sorbed species with other metal hydrous oxides, as inferred by the EXAFS-modelled second shell Fe and Al scatterers. Analysis by EXAFS also suggests that metallic Zn-Cu-Sn-Pb and Zn-silicate phases are present in the RDS, and this is corroborated by SEM and XRD. Other phases suggested by EXAFS include ZnO, franklinite, Zn-sorbed birnessite and zinc formate. Differences between the XANES and other results suggest that model compounds such as Zn-bearing phyllosilicates and metallic Zn phases may have been missing from the XANES fitting. Long-term low-level exposure to the RDS Zn phases identified may lead to an increased risk of cardiovascular or pulmonary diseases.
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Lipatnikova, O. A., T. N. Lubkova, and N. A. Korobova. "Trace element speciation in water and bottom sediments of the Pirogov water reservoir." Moscow University Bulletin. Series 4. Geology, no. 6 (December 28, 2020): 59–68. http://dx.doi.org/10.33623/0579-9406-2020-6-59-68.
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The composition and speciation of trace elements (Cu, Pb, Zn, Cd, Ni, Co, Mn, Fe, Ba, and Sr) in surface water and bottom sediments of the Pirogov water reservoir have been studied. It was found that the metal content in surface water does not exceed the maximum permissible concentration (MPC) for fishery water reservoir excluded Zn (2–9 MPC) and Cu (up to 2 MPC). According to results of thermodynamic calculations, the predominant metal speciation in water is the free ion (Sr, Ba, Zn, Ni, Co, Cd), fulvate (Cu) and carbonate (Pb) complex. The interstitial water is characterized by an increase in the content of sulfate complex of trace elements in loams, the solid phase of which is also characterized by slightly anomalous contents of Zn, Cd, Co, and Ni. According to data of sequential selective procedure, metals are predominantly immobilized in solid phase of bottom sediments in the crystal structure of silicates or bounded to iron and manganese oxides. Only for Cd and Mn exchangeable and bound to carbonates fractions are characterized by considerable relative contents.
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Morrison, G. M. P., D. M. Revitt, and J. B. Ellis. "Metal Speciation in Separate Stormwater Systems." Water Science and Technology 22, no. 10-11 (October 1, 1990): 53–60. http://dx.doi.org/10.2166/wst.1990.0288.
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Biogeochemical processes, affecting metal speciation in a gullypot system and at stormwater outfalls, are investigated. Ionic Pb and Cu species released from road sediments by add rain are scavenged by dissolved organic material and suspended solids as a result of a rise in pH through the road/gullypot system. Cadmium and Zn tend to remain in the dissolved phase. Bacterial activity and add dissolution produce increases in dissolved metal in the gullypot liquor and it is these metals which contribute to the early storm profile. Metals in basal gullypot sediments are readily mobilised during high volume/intensity storms. The resulting stormwater contains dissolved ionic forms of Cd and Zn, while Pb is mostly adsorbed to suspended solid surfaces. Copper also binds to solids, although approximately 50% is transported by dissolved organic material (molecular weight ≈ 1000-5000). For the separation of directly toxic metal species, anodic stripping voltammetry at polymer coated electrodes is preferred. Lead and Cu are present as iron/humic colloids and organic complexes respectively, which are not directly toxic to algae. Cadmium is predominantly ionic and inorganically complexed and therefore directly toxic. It is recommended that the highly toxic lipid soluble metal species should be analysed in stormwater.
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Ray, Prasenjit, and Siba Prasad Datta. "Solid phase speciation of Zn and Cd in zinc smelter effluent-irrigated soils." Chemical Speciation & Bioavailability 29, no. 1 (November 4, 2016): 6–14. http://dx.doi.org/10.1080/09542299.2016.1247656.
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Degtiareva, Antonina, and Maria Elektorowicz. "A Computer Simulation of Water Quality Change Due to Dredging of Heavy Metals Contaminated Sediments in the Old Harbour of Montreal." Water Quality Research Journal 36, no. 1 (February 1, 2001): 1–19. http://dx.doi.org/10.2166/wqrj.2001.001.
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Abstract Aquatic sediments accumulate heavy metals that are discharged into the environment. This study investigates possible water quality changes due to release of heavy metals such as Cd, Ni, Zn and Pb into the water column during dredging of anoxic sediments in the Old Harbour of Montreal. An environmental impact assessment of the sediment removal requires estimating the speciation of heavy metals in the water column with and without the solid phase. Chemical equilibria in the St. Lawrence River water are calculated using the program EQUILIB from the software FACT. Results show that the water is oversaturated with respect to CaMg(CO3)2 and Fe(OH)3. It is speculated that (ZnO)(Fe2O3) and (NiO)(Fe2O3) control the solubility of Zn and Ni in the water. The speciation of heavy metals in pore water of anoxic sediments is calculated, taking into account that the corresponding sulfides are solid phases and control their solubility. The impact of various scenarios on the area of concern is reviewed from an ecotoxicological perspective. Dredging might change the redox and acid-base conditions in the water column. Dredging can lead to an increase in the concentration of heavy metals in the water column and a change of metal speciation, but its impact will be less visible if the sediments contain high levels of calcium acting as a buffer.
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Jeyakumar, Paramsothy, Paripurnanda Loganathan, Sivalingam Sivakumaran, Christopher W. N. Anderson, and Ronald G. McLaren. "Copper and zinc spiking of biosolids: effect of incubation period on metal fractionation and speciation and microbial activity." Environmental Chemistry 5, no. 5 (2008): 347. http://dx.doi.org/10.1071/en08031.
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Environmental context. Global sewage sludge (biosolids) production is increasing as a result of rapidly growing human population and ensuing industrial activities. Disposal of this waste is becoming a serious environmental issue because the high levels of heavy metals in biosolids can upset soil microbial activity and nutrient balance when the waste is added to forest or agricultural lands. In the present study, a biosolid matrix was spiked with copper and zinc as a model for an environmental scenario. The findings of the present study are applicable to environmental regulations that seek to protect agriculture land, human and animal health, and soil and drinking water quality, in scenarios where biosolids are applied to soil. Abstract. Biosolids were amended separately with three levels of copper and zinc sulfate, and anaerobically incubated for 117 days. Copper in the unamended-biosolids solid phase was mainly found in the organic and residual fractions (85–95%). Copper addition decreased the percentage of Cu in these fractions and increased the percentage of Cu in the oxide and specifically adsorbed fractions. Zinc in the solid phase was mainly associated with the oxide (35–65%), specifically adsorbed (25–30%), and the exchangeable fractions (10–40%). Relatively, all Cu in the solution phase was complexed with organic matter; Zn was present mainly as Zn2+ and as an electrically neutral ion pair, ZnSO40. Metals were almost completely incorporated into the biosolids matrix by Day 55. Dehydrogenase activity was reduced by 50% (EC50, effective concentration for 50% activity reduction) at the total solution-phase Cu and Zn concentrations of 0.1 and 20 mg L–1, respectively, and solid-phase exchangeable Cu and Zn concentrations of 410 and 670 mg kg–1, respectively.
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Hernandez-Soriano, M. C., and J. C. Jimenez-Lopez. "Linking dissolved organic matter composition to metal bioavailability in agricultural soils: effect of anionic surfactants." Biogeosciences Discussions 12, no. 7 (April 14, 2015): 5697–723. http://dx.doi.org/10.5194/bgd-12-5697-2015.
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Abstract. The bioavailability of metals in soil is only partially explained by their partition among the solid and aqueous phase and is more related to the characterization of their speciation in the soil solution. The organic ligands in solution that largely determine metal speciation involve complex mixtures and the characterization of fluorescence components of dissolved organic matter (DOM) can identify pools of molecules that participate in metal speciation, this being essential for risk assessment. The bioavailability of Cd, Cu, Pb and Zn in three agricultural soils was examined in the laboratory to recreate irrigation with greywater enriched in anionic surfactants (Aerosol 22 and Biopower). Field capacity and saturation regimes were considered for this study. Irrigation with aqueous solutions of the anionic surfactants increased total DOM concentrations and metals in the soil solution (Pb > Cu > Zn > Cd). Significant correlation (p < 0.05) between the readily available pool of metals with the concentration of DOM was determined for Cu (r = 0.67), Pb (r = 0.82) and Zn (r = 0.68). However, speciation analysis performed with the software WHAM indicated that mobilisation of DOM and metals into the soluble phase resulted in a low concentration of free ion activities and promoted the formation of metal-organo complexes. The characterization of fluorescence components revealed that DOM in soil solution from soils irrigated with Aerosol 22 was enriched in a reduced quinone-like and a humic-like component. Besides, fluorescence quenching provided further evidence of metal complexation with organic ligands in solution. Hence, metal mobilization in soil irrigated with surfactant enriched greywater occurs with solubilisation of high affinity organic ligands, which substantially decreases the potential risk of metal toxicity.
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Degtiareva, A., and M. Elektorowicz. "Change in the water quality of industrial channels due to resuspension of sediments contaminated with heavy metals." Water Supply 1, no. 2 (March 1, 2001): 27–35. http://dx.doi.org/10.2166/ws.2001.0018.
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Industrial channels were used extensively during the two previous centuries and have become heavily contaminated. This study investigates possible water quality changes in the Lachine Canal (Montreal) due to the release of heavy metals (Cd, Ni, Zn and Pb) into the water column during resuspension of anoxic sediments subjected to potential remediation. This release can be initiated by dredging activities for sediment removal. Equilibrium in the water from the Lachine Canal has been calculated using the program EQUILIB from the software FACT. The speciation of heavy metals in the water column was calculated with and without a solid phase before and after possible dredging. Speciation of heavy metals in pore water of anoxic sediments has been calculated, taking into account that corresponding sulfides are the solid phases controlling their solubility. The concentration of heavy metals under anoxic conditions considered could decrease by 8 orders of magnitude. The impact of various scenarios in the area of concern was reviewed from an ecotoxicological perspective. Dredging can possibly change the redox and acid–base conditions in the water column. The impact of dredging will be less if sediments contain calcium. Dredging can lead to an increase in the concentration of heavy metals in the water column and a change of metal speciation.
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Goen, Ho, and Qiao Liang. "Chromium speciation in municipal solid waste: effects of clay amendment and composting." Water Science and Technology 38, no. 2 (July 1, 1998): 17–23. http://dx.doi.org/10.2166/wst.1998.0093.
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The addition of clay in the form of bauxite refining residue (red mud) prior to composting has been suggested as a way to control heavy metal mobility in compost. Leachability and plant availability of metals in a mixture of grass clippings and sawdust spiked with metal solution was markedly reduced during the composting process. The fate of metals in municipal solid waste compost applied to land was examined by using a sequential step extraction to investigate metal speciation (into exchangeable and bound to carbonate forms, to Mn & Fe oxides, to organic matter and in residue phase) in red mud amended compost. The effects of red mud and the composting process on metal speciation in the compost for Cd, Cr, Cu, Ni, Pb and Zn were investigated, and a comparison of some effects with biosolids compost was made. Addition of red mud reduced the metal mobility and the potential hazard of releasing metals from compost through promoted precipitation, adsorption and complexation of free metal cations to red mud. Red mud however, was not able to desorb metals bound to organic matter. Since most of the metals in the municipal solid waste were not usually bound to organic matter, the addition of red mud prior to composting fixed the free metal ions before they bound to this fraction. Results for Cr speciation are reported in this paper.
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García-Meza, J. V., M. I. Contreras-Aganza, J. Castro-Larragoitia, and R. H. Lara. "Growth of Photosynthetic Biofilms and Fe, Pb, Cu, and Zn Speciation in Unsaturated Columns with Calcareous Mine Tailings from Arid Zones." Applied and Environmental Soil Science 2011 (2011): 1–9. http://dx.doi.org/10.1155/2011/732984.
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Mine tailing remediation aims to reduce the rate of sulfide mineral oxidation. Earlier studies showed that photosynthetic biofilms may act as a physical barrier against oxygen diffusion. Currently, a long-term assay (6 months) is required to evaluate the solid phase redistribution of the Pb, Fe, Cu, and Zn originally present in historic and calcareous mine tailing samples (in our case from a semiarid region in North-Central Mexico). The presence of biofilms may provide chemical gradients and physical conditions that shift the proportion of Fe, Cu, and Zn originally associated with oxides to carbonates and organic matter/sulfide fractions.
Dissertations / Theses on the topic "Zn solid phase speciation"
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Miller, Carrie Lynn. "The role of organic matter in the dissolved phase speciation and solid phase partitioning of mercury." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3357.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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King, Amanda Jane. "The speciation and geochemical reactivity of polycyclic aromatic hydrocarbons in marine water and sediments." Thesis, University of Sussex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273158.
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Bérillon, Laurent. "Mg- and Zn-Mediated Synthesis of Heterocycles in Solution and on the Solid Phase." Diss., lmu, 2000. http://nbn-resolving.de/urn:nbn:de:bvb:19-1954.
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Jonsson, Sofi. "Unraveling the importance of solid and adsorbed phase mercury speciation for methylmercury formation, evasion and bioaccumulation." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64286.
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Monomethylmercury, MeHg, is formed under anoxic conditions in waters, sediments and soils and then bioaccumulated and biomagnified in aquatic food webs, negatively effecting both human and wildlife health. It is generally accepted that precipitation of mercury, Hg, and adsorption of Hg to e.g. organic matter and mineral surfaces are important processes limiting the reactivity of Hg mobilized in the environment by natural and anthropogenic activities. However, knowledge concerning the role of different solid and adsorbed chemical forms of Hg for MeHg formation, evasion and bioaccumulation is missing. Such information is vital for the understanding of environmental processes controlling MeHg formation and bioaccumulation, as well as for predicting how changes in e.g. loading rates of atmospheric Hg and the outcome of climate change scenarios and anthropogenic land use could alter Hg concentrations in biota. In this thesis, a novel experimental approach, using isotopically enriched solid and adsorbed phases of inorganic Hg, HgII, as tracers, was developed. Using this approach, we successfully determined rates of MeHg formation from solid and adsorbed Hg species in sediment slurries and in mesocosm systems under conditions closely resembling those in field. We conclude that the solid/adsorbed phase speciation of HgII is a major controlling factor for MeHg net formation rates. Microcosm experiments revealed that newly formed MeHg was a major contributor to the evasion of MeHg from the water‒sediment system, emphasizing the importance of MeHg formation rate, rather than MeHg concentration, in the sediment for this process. From mesocosm systems, we provide experimental evidence, as well as quantitate data, for that terrestrial and atmospheric sources of HgII and MeHg are more available for methylation and bioaccumulation processes than HgII and MeHg stored and formed in sediments. This suggests that the contribution from terrestrial and atmospheric sources to the accumulation of Hg in fish may have been underestimated. As a consequence, in regions where climate change is expected to further increase land runoff, terrestrial MeHg sources may have even higher negative effects on biota than previously thought. Data and concepts presented in this thesis lay the basis for unprecedented in-depth modeling of processes in the Hg biogeochemical cycle that will improve our understanding and the predicting power on how aquatic ecosystems may respond to environmental changes or differences in loading rates for atmospheric Hg.Monometylkvicksilver, MeHg, bildas under anoxiska förhållanden i naturliga vatten, sediment och jordar och bioackumuleras och magnifieras därefter i den akvatiska näringskedjan med negativa effekter på djur och människor som följd. Det är generellt vedertaget att utfällning av Hg och adsorption av Hg till exempelvis organiskt material och mineralytor begränsar tillgängligheten för biogeokemiska reaktioner av Hg som mobiliserats i miljön via naturliga och antropogena processer. Kunskap om betydelsen av speciationen av Hg i fasta och adsorberade faser för bildning, avgång och bioackumulering av MeHg är dock bristfällig. Denna information är kritisk för att förstå vilka processer som kontrollerar bildning och bioackumulering av MeHg samt för att kunna prediktera hur olika ekosystem kan förväntas svara på exempelvis ändrad deposition av atmosfäriskt Hg eller hur klimatförändringar kan påverka koncentrationerna av Hg i fisk. I denna avhandling har en experimentell metod utvecklades, där isotopanrikade fasta och adsorberade kemiska former av oorganiska tvåvärt Hg, Hg II används som s.k. "tracers". Denna metod användes för att bestämma MeHg bildningshasigheter i homogeniserade sediment prover samt i mesokosmsystem där förhållandena efterliknar de som förväntas i naturliga ekosystem. Från dessa drar vi slutsatsen att speciationen av HgII i fast/adsorberad fas är en viktig kontrollerande faktor som begränsar nettobildningen av MeHg. Mikrokosmexperiment visade att i första hand nyligt bildad MeHg avgick till gasfas vilket understryker betydelsen av MeHg bildningshastighet, snarare än koncentration, i sedimentet för denna process. Från mesokosmexperimenten visar vi, med kvantitativa data, att terrestra och atmosfäriska källor av HgII och MeHg är mer tillgängliga för bildning och bioackumulering av MeHg än HgII och MeHg lagrat eller bildat i sedimenten. Orsaken till detta är framförallt skillnad i speciationen av Hg i fasta/adsorberade faser. Detta innebär att bidraget från MeHg från terrestra och atmosfäriska källor till koncentrationen av Hg i fisk kan ha underskattats, samt att de negativa effekterna på MeHg exponering i områden där exempelvis klimat-förändringar förväntas leda till ökad terrest avrinning kan bli mer allvarliga än vad som tidigare predikterats. Data som presenteras i denna avhandling möjliggör modellering av Hg’s biogeokemiska cykel på en ny detaljnivå samt möjliggör säkrare prediktioner av hur olika ekosystem kan förväntas svara mot miljöförändringar eller ändrad deposition av atmosfäriskt Hg.
Till Finansiärer skall också följande läggas till: Kempe stiftelsen (SMK-2942, SMK-2745, JCK-2413).
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CEYLAN, OZCAN. "ELECTROCHEMICALLY-AIDED CONTROL OF SOLID PHASE MICRO-EXTRACTION (EASPME) USING CONDUCTING POLYMER COATED FIBER." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069853643.
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Moberly, James Gill. "Influences of chemical speciation and solid phase partitioning on microbial toxicity single organism to in situ community response /." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/moberly/MoberlyJ0510.pdf.
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The waters and sediments of Lake Coeur d'Alene (LCDA) in northern Idaho have been contaminated by heavy metals because of decades of mining operations. Metal speciation is critical in assessing toxicity because it may vary considerably with pH and is dependent on other aqueous constituents. There has been little research on integrated investigations of the effects of heavy metal speciation on indigenous microbes from LCDA, especially large scale community analysis. The focus of this research in the LCDA system was to determine the effect of heavy metal speciation on toxicity, first in a defined single organism system, followed by in situ studies. Combined results of thermodynamic modeling, statistical analysis, and batch culture studies using Arthrobacter sp. JM018 suggest that the toxic species is not solely limited to the free ion, but also includes ZnHPOâ‚„â°(aq). Cellular uptake of ZnHPOâ‚„â°(aq) through the inorganic phosphate transporter (pit family), which requires a neutral metal phosphate complex for phosphate transport, may explain the observed toxicity. These findings show the important role of "minor" Zn species in organism toxicity and have wider implications since the pit inorganic phosphate transport system is widely distributed in bacteria, archaea, and eukaryotes. Using a multivariate statistical approach, correlations between the microbial community (via 16S rDNA microarray) in sediment cores and operationally defined heavy metal phases (via continuous sequential extractions) were explored. Candidate phyla NC10, OP8 and LD1PA were only present in metal contaminated cores and diversity doubled among Natronoanaerobium in metal contaminated cores which may suggest some increased fitness of these phyla in contaminated sediments. Correlations show decreases in diversity from presumed sulfate reducing lineages within most taxa from Desulfovibrionales and Bdellovibrionales and from metal reducing bacterial lineages Shewanellaceae, Geobacteraceae, and Rhodocyclaceae with increases in the ratio of more bioavailable Pb exchangeable/carbonate to less bioavailable Pb oxyhydroxide. This is the first time these techniques have been used in combination to describe a contaminated system.
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Reinoso-Maset, Estela. "Aqueous and solid phase interactions of radionuclides with organic complexing agents." Thesis, University of Plymouth, 2010. http://hdl.handle.net/10026.1/300.
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Characterising the geochemistry and speciation of major contaminant radionuclides is crucial in order to understand their behaviour and migration in complex environmental systems. Organic complexing agents used in nuclear decontamination have been found to enhance migration of radionuclides at contaminated sites; however, the mechanisms of the interactions in complex environments are poorly understood. In this work, radionuclide speciation and sorption behaviour were investigated in order to identify interactions between four key radionuclides with different oxidation states (Cs(I) and Sr(II) as important fission products; Th(IV) and U(VI) as representative actinides), three anthropogenic organic complexing agents with different denticities (EDTA, NTA and picolinic acid as common co-contaminants), and natural sand (as simple environmental solid phase). A UV spectrophotometric and an IC method were developed to monitor the behaviour of EDTA, NTA and picolinic acid in the later experiments. The optimised methods were simple, applied widely-available instrumentation and achieved the necessary analytical figures of merit to allow a compound specific determination over variable background levels of DOC and in the presence of natural cations, anions and radionuclides. The effect of the ligands on the solubility of the radionuclides was studied using a natural sand matrix and pure silica for comparison of anions, cations and organic carbon. In the silica system, the presence of EDTA, NTA and, to a lesser extent, picolinic acid, showed a clear net effect of increasing Th and U solubility. Conversely, in the sand system, the sorption of Th and U was kinetically controlled and radionuclide complexation by the ligands enhanced the rate of sorption, by a mechanism identified as metal exchange with matrix metals. Experiments in which excess EDTA, NTA and picolinic acid (40 – 100 fold excess) were pre-equilibrated with Th and U prior to contact with the sand, to allow a greater degree of radionuclide complex formation, resulted in enhanced rates of sorption. This confirmed that the radionuclide complexes interacted with the sand surface more readily than uncomplexed Th or U. Overall this shows that Th and U mobility would be lowered in this natural sand by the presence of organic co-contaminants. In contrast, the complexation of Sr with the complexing agents was rapid and the effect of the ligands was observed as a net increase on Sr solubility (EDTA, picolinic acid) or sorption (NTA). As expected, Cs did not interact with the ligands, and showed rapid sorption kinetics. Finally, ESI-MS was used to study competitive interactions in the aqueous Th-Mn-ligand ternary system. Quantification presented a challenge, however, the careful approach taken to determine the signal correction allowed the competitive interactions between Mn and Th for EDTA to be studied semi-quantitatively. In an EDTA limited system, Th displaced Mn from the EDTA complex, even in the presence of a higher Mn concentration, which was consistent with the higher stability constant of the Th-EDTA complex.
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Ambushe, AA, RI McCrindle, and CME McCrindle. "Speciation of chromium in cow’s milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)." The Royal Society of Chemistry, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001492.
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Chromium can act either as an essential micronutrient or a chemical carcinogen, depending on its
oxidation state. Of the two most stable chromium oxidation states, Cr(VI) is a known carcinogen, while
Cr(III) is an essential element. Determination of total Cr cannot therefore be used to evaluate food
safety of dairy products, as speciation is required for accurate assessment of potential toxicity. In this
study, total Cr was determined by DRC-ICP-MS after mineralisation of freeze-dried milk samples.
Chromabond NH2 ion-exchange columns were used to separate Cr(VI) from Cr(III). During the
separation process, Cr(VI) was selectively adsorbed onto the Chromabond NH2 column. The retained
Cr(VI) was subsequently eluted with two column volumes of 2 M HNO3 and diluted to a final volume
of 10 mL. After separation, the Cr(VI) was quantified by DRC-ICP-MS, using O2 as the reactive gas, to
alleviate polyatomic ion interference. An O2 gas flow rate of 0.85 ml/min and a high-pass rejection
parameter q (Rpq) ¼ 0.5, provided the best compromise signal-to-noise ratio. The method was
validated through determining the recovery in milk samples spiked with Cr(VI). The recoveries were
quantitative and ranged from 96.4 to 99.2%. A whole milk powder reference material (NIST SRM
8435) was used to evaluate the accuracy of the total Cr quantification method. The observed value
showed concordance with the certified value. The limits of detection (LOD) were 0.091 and 0.085 mg/L
for total Cr and Cr(VI), respectively. These findings are important for the determination of maximum
residue levels (MRLs) of Cr(VI) in dairy products.
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MacDonald, James Douglas. "The partitioning of Cd, Cu, Pb and Zn between the solid and solution phase of forest floor horizons in podzolic soils near metal smelters /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85575.
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The emission of trace metals (TMs) into boreal forest regions of the northern hemisphere is an important environmental issue due to their potential detrimental impacts on these sensitive ecosystems. One of the foremost factors controlling metal cycling is the chemistry of the overlying organic forest floor of the forest soil. In this thesis we examine the chemistry of forest floor horizons of podzolic soils. Our goal is to improve our ability to predict the partitioning of metals between the soil solid and solution phases.We developed a standard protocol to produce solutions that resemble lysimeter solutions from podzolic soils using air-dried samples. We hypothesized that the stabilization point of the electrical conductivity (EC) of the soil solution is indicative of the point in which soluble salts and organic material precipitated during sampling and storage are removed from the soil particle surfaces. Solutions produced by leaching the soils, once the EC of wash solutions had stabilized, were comparable to lysimeter solutions from the area where samples were collected with respect to the concentrations of divalent cations, pH, EC and dissolved organic carbon (DOC). The applicability of this procedure to trace metal partitioning in forest floors was explored. Laboratory extractions produced partition coefficients (log Kd) similar to observed lysimeter solutions ranging from 3.4 to 3.9 for Cd, 3.4 to 3.9 for Cu, 3.4 to 4.1 for Ni, 4.1 to 5.2 for Pb and 3.2 to 3.5 for Zn. According to a semi-mechanistic regression model based on observed lysimeter concentrations, the metal concentrations in solution were appropriate relative to known factors that influence metal partitioning in soils: pH, the concentrations of total metals and DOC.
While chemical characteristics of soils have been consistently observed to play important roles in the partitioning and toxicity of metals we wished to place the importance of the chemical characteristics of soil on mobility and toxicity in context. We interpreted field data that had been collected from transects established with distance from two point source emitters in Rouyn PQ, and Sudbury ON. Canada find developed equations that predict dissolved metal concentrations from total metal concentrations, soil pH, soil organic matter (SOM), and DOC contents. We integrated these equations into a simple box model that calculates changes in the concentration of metals in the organic and upper mineral horizons and includes a loop for vegetative return of metals to the forest floor.
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Lopes, Aline Soriano. "Extração de especies organoestancias em sedimento por microextração em fase solida acoplada ao forno de grafite e determinação de estanho total por amostragem em suspensão." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248604.
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Orientadores: Marco Aurelio Zezzi Arruda, Fabio AugustoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Este trabalho de Tese visa acoplar a fibra, empregada em microextração em fase sólida (SPME, do inglês solid phase microextraction), ao espectrômetro de absorção atômica com forno de grafite (GF AAS, do inglês graphite furnace atomic absorption spectrometer), visando reter espécies organometálicas volatilizadas nas etapas de secagem e pirólise do GF AAS. O elemento escolhido para avaliar o acoplamento SPME-GF AAS foi o Sn. Primeiramente, a concentração total de Sn foi determinada, utilizando a amostragem em suspensão como estratégia, uma vez que na avaliação da distribuição dos compostos organoestânicos por SPME-GF AAS, a concentração total de Sn seria efetuada a partir de uma suspensão. Para a otimização do método foram avaliados os seguintes parâmetros: solução de preparo da suspensão, e efeito da temperatura de pirólise e atomização. A mistura contendo HF 10 % (v/v) e HNO3 1 % (v/v) foi escolhida para preparar a suspensão, a composição Mg(NO3)2 + NH4H2PO4 apresentou resultados apropriados para ser utilizada como modificador químico convencional, e 1000 e 2200 °C foram as temperaturas ótimas para a pirólise e a atomização, respectivamente. Devido ao efeito de matriz, foi utilizada a técnica de adição de analito para a quantificação de Sn em suspensões de sedimento marinho e de rio, em que os limites de detecção e quantificação calculados foram de 1,5-2,6 e 4,5- 7,6 µg g, respectivamente. Para avaliar o acoplamento SPME-GF AAS, visando à retenção das espécies organoestânicas (butiltricloroestanho, dibutildicloroestanho e tributilcloroestanho) foi utilizada, primeiramente, uma suspensão de sedimento. A suspensão foi sonicada e, em seguida, uma alíquota foi injetada no forno de grafite do GF AAS juntamente com o reagente de derivação (tetraetilborato de sódio - NaBEt4). A programação do forno de grafite foi aplicada e a fibra de SPME foi introduzida no atomizador. Após a retenção das espécies de interesse na fibra, a mesma foi conduzida ao cromatógrafo a gás (CG) para a separação e detecção dos analitos. Os parâmetros instrumentais do CG foram previamente estudados, visando a melhor separação das espécies de interesse. Esses estudos foram realizados utilizando o modo de extração por headspace e SPME (HS-SPME, do inglês headspace-solid phase microextraction). Em relação aos estudos envolvendo suspensões de sedimento no acoplamento proposto SPME-GF AAS, alguns parâmetros foram avaliados frente à retenção das espécies de interesse; entre eles pode-se citar o tipo de fibra, a concentração do reagente de derivação e o pH da reação. Melhores resultados foram observados para a fibra PDMS/DVB, utilizando uma concentração de 0,2 % (m/v) de NaBEt4 para a etilação das espécies de interesse, sendo a reação realizada em pH 5,0. Entretanto, baixa eficiência de retenção (< 20 %) das espécies de interesse em suspensão de sedimento, foi obtida utilizando-se o acoplamento SPME-GF AAS, quando comparada à extração por HS-SPME. Dessa forma, foi realizada uma extração das espécies de interesse das amostras de sedimento, utilizando a energia ultrassônica, anteriormente à sua aplicação no acoplamento proposto SPME-GF AAS. Nesta etapa do trabalho, a temperatura do forno de grafite e o tempo de exposição da fibra de SPME no forno de grafite foram otimizados, visando à máxima eficiência de retenção das espécies de interesse no acoplamento SPME-GF AAS. Os melhores resultados foram observados para temperaturas do forno de grafite de 90 °C, com 986 s de tempo de exposição da fibra no atomizador. Por fim, foram realizados experimentos visando determinar a concentração total de Sn, e reter suas espécies organometálicas simultaneamente, na fibra de SPME, utilizando o acoplamento SPME-GF AAS.
Abstract: The goal of this Thesis was coupling the solid phase microextraction (SPME) to graphite furnace atomic absorption spectrometer (GF AAS) for extracting the organometallic species volatilized in the drying and pyrolysis steps of the GF AAS. For evaluating the SPME-GF AAS coupling, Sn was then chosen. Firstly, the total Sn concentration using the slurry sampling strategy was determined, once in the evaluation of the organotin compounds by SPME-GF AAS, the total Sn concentration would be obtained from a slurry solution. Some parameters were evaluated, such as the nature of the solution to prepare the slurry, and pyrolysis and atomization temperatures effects. The mixture of 10 % (v/v) HF plus 1 % (v/v) HNO3 was chosen to prepare the sediment slurries, the Mg(NO3)2 plus NH4H2PO4 was appropriated as conventional chemical modifier, and the values of 1000 and 2000 °C was used as pyrolysis and atomization temperatures, respectively. The analyte addition was used in the Sn determination in sediment (marine and river) samples by slurry sampling due to matrix effects. The detection and quantification limits were calculated as 1.5-2.6 and 4.5-7.6 µg g, respectively. For evaluating the SPME-GF AAS coupling in the extraction of organotin species (butyltrichloride, dibutyldichloride, and tributylchloride), a sediment slurry was firstly used. For this task, the slurry was sonicated and an aliquot of this solution plus the derivatization reagent (sodium tetraethylborate ¿ NaBEt4) were introducted consecutively into the graphite furnace of the GF AAS. Then, the graphite furnace program was applied, and the SPME fiber was exposed into the furnace. After the extraction of organotin species by SPME-GF AAS, the analytes were separated and detected by gas chromatography (GC). Before this procedure, instrumental parameters of the GC were studied. For this task, it was used the conventional extraction by HSSPME (headspace-solid phase microextraction). Related to studies of SPME-GF AAS coupling, employing slurry sampling, some parameters, such as fiber coating, derivatization reagent concentration, pH of the reaction, among others, were evaluated. Satisfactory results were obtained using the PDMS/DVB fiber in the presence of 0.2 % (m/v) NaBEt4 and pH 5.0. However, low extraction efficiency (< 20 %) was obtained, using the SPME-GF AAS coupling for organotin species extraction from sediment slurries, when comparing to HS-SPME extractions. Then, the extraction of organotin species from sediment samples, using the ultrasonic energy was carried out, before the sample introduction into the SPME-GF AAS coupling. In this step, the graphite furnace temperature and the fiber exposure time in the atomizer were optimized. The better results were noted when 90 °C as the graphite furnace temperature was used, and 986 s was attributed as the fiber exposure time into the atomizer. Additionally, the determination of total Sn concentration, and the extraction of organotin species in the SPME fiber, using the SPME-GF AAS coupling, was simultaneously carried out.
Doutorado
Quimica Analitica
Doutor em Ciências
Books on the topic "Zn solid phase speciation"
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Bos, Mark C. Part I: Development and application of an arsenic speciation technique using ion-exchange solid phase extraction coupled with GFAAS ; Part II : investigation of zinc amalgam as a reductant. 1996.
Find full textBook chapters on the topic "Zn solid phase speciation"
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Gómez, Denys Kristalia Villa. "Effect of pH on the Morphology, Mineralogy and Solid-Liquid Phase Separation of Cu and Zn Precipitates Produced with Biogenic Sulfide." In Simultaneous Sulfate Reduction and Metal Precipitation in an Inverse Fluidized Bed Reactor, 121–45. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003059318-6.
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Kashem, Abul, and Bal Singh. "Solid-Phase Speciation of Cd, Ni, and Zn in Contaminated and Noncontaminated Tropical Soils." In Trace Elements in Soil. CRC Press, 2001. http://dx.doi.org/10.1201/9781420032734.ch11.
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Wauters, J., M. J. Madruga, M. Vidal, and A. Cremers. "Solid phase speciation of radiocaesium in bottom sediments." In Freshwater and Estuarine Radioecology, Proceedings of an International Seminar, 165. Elsevier, 1997. http://dx.doi.org/10.1016/s0166-1116(09)70092-5.
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Skoko, Željko, and Stanko Popović. "Microstructure of Al-Cu, Al-Zn, Al-Ag-Zn, and Al-Zn-Mg Alloys." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000172.
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The precipitation phenomena and their connection with the microstructure of several Al alloys (Al-Cu, Al-Zn, Al-Ag-Zn, Al-Zn-Mg) are described with respect to the concentration and applied thermal treatment. The alloys were rapidly quenched or slowly cooled from a temperature higher than the solid solution temperature to room temperature. Both quenched-aged and slowly cooled alloys were heated from room temperature to the solid solution state and cooled back to room temperature, and their microstructure and precipitation phenomena were followed in situ by X-ray powder diffraction, e.g., anisotropy of thermal expansion, phase transitions, thermal hysteresis in phase transitions, change of precipitate shape, partial or complete dissolution of precipitates in the matrix, and formation of solid solution. It has been shown that the microstructure strongly depends on the previous thermal history of the alloys.
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Nieva, N., L. Borgnino, and M. García. "Solid-phase speciation of arsenic in abandoned mine wastes from the northern Puna of Argentina using X-ray absorption spectroscopy." In Arsenic in the Environment - Proceedings, 265–67. CRC Press, 2016. http://dx.doi.org/10.1201/b20466-129.
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Saxena, Pallavi, and Anand Yadav. "Effect of Transition Metal on Structural and Dielectric Properties of Mg0.5Tm0.5Fe2O4 (Tm = Zn and Cu) System." In Transition Metal Compounds - Synthesis, Properties, and Application. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96729.
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This study explored the structural and dielectric features of Mg0.5Tm0.5Fe2O4 (Tm = Zn and Cu) that were synthesized by the Solid-state reaction (SSR) method. The X-ray powder diffraction (XRD) analysis reveals that the prepared samples are single-phase cubic structure without any impurity. Rietveld-refined X-ray diffraction results reveal the formation of cubic structure and all the peaks of Mg0.5Zn0.5Fe2O4 and Mg0.5Cu0.5Fe2O4 are perfectly indexed in the cubic (Fd-3 m) structure. Dielectric constant and dielectric loss variation with frequency were also explored. Both decrease when the relevant alternating field is increasing and become constant at high frequencies which reflects the important role of interfacial polarization. Furthermore, the Mg0.5Cu0.5Fe2O4 having the smallest crystallite size (~ 44.73 nm) has a high dielectric constant (~ 4.41 × 104) value as compare to Mg0.5Zn0.5Fe2O4.
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Srinivasan, Sesha, Luis Rivera, Diego Escobar, and Elias Stefanakos. "Light Weight Complex Metal Hydrides for Reversible Hydrogen Storage." In Advanced Applications of Hydrogen and Engineering Systems in the Automotive Industry. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95808.
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We have investigated the complex metal hydrides involving light weight elements or compounds for the reversible hydrogen storage. The complex hydrides are prepared via an inexpensive solid state mechanochemical process under reactive atmosphere at ambient temperatures. The complex metal hydride, LiBH4 with different mole concentrations of ZnCl2 were characterized for the new phase formation and hydrogen decomposition characteristics of Zn(BH4)2. Furthermore, the complex metal hydride is destabilized using the addition of nano MgH2 for the reversible hydrogen storage characteristics. The structural, microstructural, surface, and other physicochemical behaviors of these lightweight complex metal hydrides have been studied via various metrological tools such as x-ray diffraction, Fourier transform infrared spectroscopy, thermal programed desorption, and PCT hydrogen absorption methods.
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Yuzevych, Volodymyr, and Bohdan Koman. "MATHEMATICAL AND COMPUTER MODELING OF INTERPHASE INTERACTION IN HETEROGENEOUS SOLID STRUCTURES." In Theoretical and practical aspects of the development of modern scientific research. Publishing House “Baltija Publishing”, 2022. http://dx.doi.org/10.30525/978-9934-26-195-4-14.
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The aim of this work was to develop a mathematical model and computer modelling of interphase interaction, mechanical stresses and adhesion mechanisms between mechanically inhomogeneous media (different phases). Methodology. For the system "metal – dielectric" we use a macroscopic approach, which corresponds to the ratio of non-equilibrium thermodynamics and physics of solid surfaces. Let’s consider the system of equations and boundary conditions for describing the change of energy parameters (σh, γ), which characterize the thermodynamic state of the system of contacting bodies. Method for calculating the main energy parameters (interfacial energy – γm, interfacial tension – σm, work of adhesion – Aadand energy of adhesive bonds – γad) in complex solid-state structures containing boundary phases is proposed. Based on the basic equations of nonequilibrium thermodynamics and surface physics a mathematical model of the interphase boundary is designed. A comparative analysis of the features of interphase interaction in the systems "metal-metal", "metal-semiconductor" and "metal-dielectric" on the example of interacting systems "Cu – Zn", "Cu – Si" and "Cu – quartz". It is established that the most sensitive parameter in the analysis of interphase interactions is the interphase energy γm.A model of mechanical stress formation in the "condensate-substrate" system is proposed. In particular, internal stresses in metal condensates are caused by changes in the value of interphase energy parameters (primarily interfacial tension) in the substrate-nanocondensate system and due to phase-forming processes accompanied by changes in surface energy in the condensate volume during its formation. The resulting internal stresses in metal condensates are an integral result of the action of statistically distributed on the plane of the film local stresses. Such phenomena are due to the anisotropy of the energy parameters of the interphase interaction in the condensate plane. Behavior analysis of energy and adhesion parameters can be used to predict the results of interphase interaction in order to select contact pairs to create thermodynamically stable structures with predicted values of energy parameters of interphase interaction, a certain type of chemical bond and a given level of mechanical stresses.
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Kosuge, Koji. "Examples of the Practical Use of Non-Stoichiometric Compounds." In Chemistry of Non-stoichiometric Compounds. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780198555551.003.0006.
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In this chapter, we describe four kinds of non-stoichiometric compound, which are or will be in practical use, from the viewpoint of preparation methods or utility. As a first example, the solid electrolyte (ZrO2)0.85(CaO)0.15 is described, which are discussed in Sections 1.4.6–1.4.8 from the viewpoint of basic characteristics. The second example is the magnetic material Mn–Zn ferrite, for which the control of non-stoichiometry and the manufacturing process will be described. Then the metal hydrides or hydrogen absorbing alloys, which are one of the most promising materials for storing and transporting hydrogen in the solid state, are described, mainly focusing on the phase relation. Finally, we describe the relation between the control of composition and the growth of a single crystal of the semiconductive compound GaAs, which is expected to give electronic materials for 1C and LSI etc. Solid electrolytes, which show ionic conductivity in the solid state, are considered to be potential materials for practical use, some are already used as mentioned below. Solid electrolytes have characteristic functions, such as electromotive force, ion selective transmission, and ion omnipresence. Here we describe the practical use of calcia stabilized zirconia (CSZ), (ZrO2)0.85(CaO)0.15, the structure and basic properties of which are discussed in detail in Sections 1.4.5–1.4.8. The most simple practical application of CSZ is for the gauge of oxygen partial pressure, as mentioned in Sections 1.4.7 and 1.4.8. The oxygen partial pressure P2o2 in the closed system as shown in Fig. 3.1 can be measured, taking the air as the standard oxygen pressure P1o2. The electromotive force (EMF) of this concentration cell is expressed as . . . E = (RT/4F)ln(P1o2/ P2o2) . . . This principle is applied in the measurement of oxygen partial pressure in laboratory experiments and of the oxygen activity of slag in refineries. Based on the principle of coulometric titration (see Section 1.4.8), the oxygen partial pressure of a closed system can be kept constant by feedback of the EMF, in the oxygen pressure range 1 to 10−7 atm. By use of this closed system, investigations on redox reactions of metals and also enzyme reactions have been carried out.
Conference papers on the topic "Zn solid phase speciation"
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Basta, Nicholas, Brooke N. Stevens, Shane D. Whitacre, Kirk G. Scheckel, Aaron R. Betts, Karen Bradham, and Richard H. Anderson. "PREDICTING ARSENIC BIOAVAILABILITY IN CONTAMINATED SOILS BY USING IN VITRO GASTROINTESTINAL BIOACCESSIBILITY AND SOLID PHASE SPECIATION FOR SITE-SPECIFIC RISK ASSESSMENT." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-369208.
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Cai, Qinhong, Tsz-Wai Ng, Kin-Hang Wong, Po-Keung Wong, Ya Xiong, Yonghua Wang, and Ying Zhang. "Speciation of Cr(III) and Cr(VI) in the Presence of Chromium Azo Dye Acid Yellow 99 by Column Solid Phase Extraction." In 2012 International Conference on Biomedical Engineering and Biotechnology (iCBEB). IEEE, 2012. http://dx.doi.org/10.1109/icbeb.2012.360.
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Tolcher, Anthony, Hirva Mamdani, Pavani Chalasani, Funda Meric-Bernstam, Mihaela Gazdoiu, Lukas Makris, Philippe Pultar, and Dimitris Voliotis. "Abstract CT016: Clinical activity of single-agent ZN-c3, an oral WEE1 inhibitor, in a phase 1 dose-escalation trial in patients with advanced solid tumors." In Proceedings: AACR Annual Meeting 2021; April 10-15, 2021 and May 17-21, 2021; Philadelphia, PA. American Association for Cancer Research, 2021. http://dx.doi.org/10.1158/1538-7445.am2021-ct016.
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Reed, G. P., D. R. Dugwell, and R. Kandiyoti. "Modelling Trace Element Emissions in Co-Gasification of Sewage Sludge With Coal." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30672.
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Gasification has attracted considerable interest from water utilities as a sewage sludge disposal option, with the advantages of waste volume reduction, pathogen destruction and energy recovery. Co-gasification with coal in a larger plant (>10 MWt) employing a gas turbine for energy recovery may reduce the risk and cost of this option. However, controlling the release of trace elements such as Pb and Zn in the gas produced may be necessary to avoid corrosion, and to meet environmental requirements. A thermodynamic equilibrium model has been used to make predictions of the speciation of trace elements in the fuel gas from co-gasification of sewage sludge with coal. Experimental data from a pilot scale 2 MWt sewage sludge/coal co-gasification plant with a hot gas filter was used to test the validity of these predictions. No significant amount of Be, Co, Cu, V and Zn was predicted to be in the form of gaseous phase species, and this was confirmed by the experimental data. On the other hand, Hg and Se were predicted to be only present in gas phase species, and this was also confirmed experimentally. The elements As, B, Cd, Pb, Sb and Sn were all predicted to form a larger amount of gaseous species than was observed in the experimental measurements. Refinement of the predictions for As and B by inclusion of specific minor/trace element interactions with Ni and Ca respectively gave a better agreement with the experimental data. Whilst the experimentally-observed lowering of Pb emissions by reduction of the gas cleaning temperature from 580 °C to 450 °C was qualitatively predicted, the concentration of Pb in the fine dust removed by the hot gas filter indicates condensation at higher temperatures than predicted. The absence of thermodynamic data for the more complex minerals and adsorbed species that may be formed is thought to account for some of these differences.
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Wang, Pengtao, Hongwei Sun, Peter Y. Wong, Hiroki Fukuda, and Teiichi Ando. "Modeling of Droplet-Based Processing for the Production of High-Performance Particulate Materials Using Level Set Method." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68014.
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This research is focused on a numerical investigation of dynamic and thermal processes of single droplet in the uniform droplet spray (UDS) process. The level set method (LSM) is used to assist in tracking the liquid-gas and solid-liquid interfaces during droplet’s impingement and solidification. UDS process generates mono-size droplets of desired diameter, permits stringent control of the thermal state of the droplet, and produces deposits and materials with distinctly different microstructures including Icosahedral quasicrystalline phase (I-phase) in the Mg-Zn-Y system. The conservative level set function, combined with the Navier-Stokes and energy equations have been adopted to study the deformation and heat transfer of liquid metal droplet when impacting on the substrate under supercooling condition. The effects of surface tension and contact angle on droplet’s deformation are taken into consideration. The developed simulation technique is validated both analytically and experimentally. A rapid solidification model has been integrated with LSM to simulate the rapid solidification within the deformed Mg-Zn-Y droplet predicted in the former model. It is found that the initial temperature fields and latent heat releasing during solidification have significant impact on the solidification process.
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Raengthon, Natthaphon, Jason Nikkel, Troy Ansell, and David P. Cann. "Dielectric and Piezoelectric Ceramics for High Temperature Applications." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50263.
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Perovskite materials have been widely embedded in many consumer and industrial electronics, both for capacitor applications in the case of dielectric materials, and for actuator, transducer and sensor applications in the case of piezoelectric materials. Functional devices used in high temperature environments, such as deep oil well instrumentation, geothermal exploration, and devices for aerospace applications require the persistence of materials’ properties at high temperatures. In this paper, high potential capacitor and piezoelectric ceramics for high temperature applications are presented. High dielectric constant (K) materials based on 0.8BaTiO3 – 0.2Bi(Zn1/2Ti1/2)O3 solid solutions have been shown to have superior properties for high temperature capacitor applications. Studies of the temperature dependence of the dielectric properties have shown that the composition with Ba vacancies exhibits a high relative permittivity (εr > 1150) and a low dielectric loss (tan δ < 0.05) that persist up to a temperature of 460 °C. This composition also shows a high resistivity in excess of 7.0 × 1010 Ω-cm which remains unchanged up to a temperature of 270 °C as well as a large RC time constant (RC > 20 s). In the case of high temperature piezoelectric ceramics, solid solutions of PbTiO3 – BiScO3 – Bi(M1/2Ti1/2)O3 ternary systems were studied, where M is Mg and Zn. The ratio of BiScO3 to Bi(M1/2Ti1/2)O3 was kept at 1:1, while the concentration of PbTiO3 was varied. X-ray diffraction patterns showed that tetragonal symmetry was observed in compositions which contain a high concentration of PbTiO3 (> 60 mol%). Evidence of a morphotropic phase boundary (MPB) was observed with compositions containing PbTiO3 in the range of 52–56 mol%. At 70 mol% PbTiO3 compositions, high Curie temperatures (TC) of 490 °C and 533 °C were observed for compositions containing Mg and Zn, respectively.
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Zhong, Zhaoping, Basheng Jin, Jixiang Lan, Changqing Dong, and Hongchang Zhou. "Experimental Study of Municipal Solid Waste (MSW) Incineration and Its Flue Gas Purification." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-011.
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This paper presents experimental study of fluidized absorption process for flue gas purification of co-combustion of municipal solid waste (MSW) and coal in a circulating fluidized bed Combustor (CFBC) test rig. The test rig is composed of a CFBC, coal/MSW feeding subsystem, ash cycle subsystem and flue gas purification subsystem. In the circulating fluidized bed, section area of fluidized bed is 230mm × 230mm and the freeboard is 460mm × 395mm. The total height of the test facility is 8m; height of bed and freeboard are 1.5m and 6m respectively. The preheated air enters the bed as primary air passing through distributor and provides oxygen for combustion. Six movable tubes immerged within the bed are used in adjusting the bed temperature. The cyclone separator is fixed up at the exit of chamber. The separated ashes return to chamber through the recycling feeder for decreasing the carbon content in fly ash and promoting the combustion efficiency. The flue gas from the exit of cyclone separator enters the air preheater to preheat the cold air at first, then enters the flue gas purification facility, finally be discharged into air by induced drafted fan passing through the stack. Coal is carried to a positive pressure feeding entrance by screw feeder and enters the bed. Secondary air is injected into a sealed end feeding pipe under MSW feeder, for enhancing the mixture in furnace, providing the oxygen for combustion and preventing from MSW remaining in the feeding pipe. The material of bed is silicon sand. Fluidized absorption facility for flue gas purification in MSW incineration is mainly composed of humidification system, absorption tower, flue gas reheater, fabric filter, slurry making pool, sediment pool and measurement subsystem. The temperature of flue gas from boiler by induced draft fan reduces to 120°C when flue gas enters the humidification region, which can increase the ability of acid gas absorption and prevent the slurry evaporation. When flue gas and limestone slurry enter the absorption tower, the three-phase material of gas, liquid and solid generates intense mixing and forms bubbling layer. The acid gases in flue gas are absorbed by limestone slurry, and a large amount of dusts are collected in reaction tank. Feeding oxidation air into slurry and agitating slurry simultaneously so as to promote the inner circulation of slurry and oxygenization of calcium sulphite. Flue gas passes through undulate demister which has high efficiency and low resistance, then enters fabric filter after reheating, finally be discharged into the stack by induced draft fan. The mixture of slurry and gypsum is emitted into the sediment pool through bottom and clear liquid in sediment pool returns to slurry making pool or absorption tower. The test results are as follows: the combustion efficiency is greater than 95%, the carbon content of fly ash is lower than 8%, and the loss of slag combustion is lower than 5%. When sorbent is limestone slurry, the concentration of slurry is 1%, the circulating ratio is 3, the jet rate is 5∼15m/s. The immerged depth of bubbling pipe under the slurry is 140mm. In the fluidized absorption facility for flue gas purification of MSW incineration, the desulfurization efficiency is >90%, the de-nitrification efficiency is 20∼30%, the de-chlorination efficiency is >80%, the removal efficiency of dust, heavy metal and dioxins are >99%, >98.6% and 99.35% respectively. After passing through fluidized absorption facility for flue gas purification of MSW incineration, when the concentration of O2 is 11%, the emission concentration of every components in flue gas are: SO2 is 20∼50mg/Nm3, NOx is 130∼270 mg/Nm3, HCl is 7∼12 mg/Nm3, HF is ∼8 mg/Nm3, CO2 is7∼8%, dust is 23∼67 mg/Nm3, Cr is 0.2172 mg/Nm3, Cu is 0.0454 mg/Nm3, Pb is 0.2963 mg/Nm3, Zn is 0.2074 mg/Nm3, Fe is 2.834 mg/Nm3, As is 1.112 × 10−3 mg/Nm3, Hg is 2.38 × 10−4 mg/Nm3 and dioxins is 0.1573 ng/Nm3. These emission concentrations are all lower than the Chinese emission standards. Some of them come close to the emission standards of developed country.
Reports on the topic "Zn solid phase speciation"
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Parsons, M. B. Analytical methods used to characterize the solid-phase speciation of metal(loid)s. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2011. http://dx.doi.org/10.4095/287945.
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Parsons, M. B. Analytical methods used to characterize the solid-phase speciation of metal(loid)s. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2011. http://dx.doi.org/10.4095/287964.
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Reimers, Clare E. Energy Harvesting, Electrode Processes and the Partitioning and Speciation of Solid Phase Iron and Sulfur in Marine Sediments. Fort Belvoir, VA: Defense Technical Information Center, July 2003. http://dx.doi.org/10.21236/ada416521.
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