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Showing 1 to 20 of 33 for “"oxyanions"”.
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Gas Chromatographic Determination of Inorganic Oxyanions in the Environment
Made available in DSpace on 2014-12-10T23:02:15Z (GMT). No. of bitstreams: 1 7514173.pdf: 3259775 bytes, checksum: ba3903c99d6193de1e1320b7dd2e8491 (MD5) Previous issue date: 1975
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The Influence of Oxyanions on the EDTA-Promoted Dissolution of Goethite
… silicate and oxide minerals. In natural systems oxyanions can compete with organic ligands for mineral surface sites thereby affecting ligand-promoted dissolution rates. Oxyanions can either enhance or inhibit dissolution depending upon pH. It has been suggested that the type of surface complex …
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Formation and transformation kinetics of iron oxy-hydroxides and effects of adsorbed oxyanions
… environmental contaminants and nutrients (e.g., oxyanions) through adsorption. Ferrihydrite is metastable and eventually transforms to hematite (Hm), goethite (Gt), and lepidocrocite (Lp). Although the Fh formation and transformation and oxyanion adsorption on its surface have been separately …
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Distortions in the tetrahedral oxyanions of crystalline substances, with crystal structure refinements of slawsonite and celsian
… parameters currently in use. Among tetrahedral oxyanions of non-transition elements, ELDP values of those exhibiting small bond-length distortions (e.g., LiO₄⁷⁻ and Ga₄⁵⁻) increase with the number of shared edges. For the oxyanions that show small edge-length distortions (e.g., Po₄³⁻ and SO₄²⁻) …
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On Competitive Adsorption of Oxyanions by Soils (Freundlich Equation, Enthalphy of Adsorption, Selectivity Coefficient, Anion Mixtures, Anion)
The adsorption behavior of anionic mixtures (binary-solute combinations of arsenate, molybdate, and phosphate) by three soil samples (Cecil clay, EPA-14, and Catlin silt loam) was investigated using batch equilibrium techniques. The adsorption of arsenate and molybdate by all three soils was …
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High-Resolution Multinuclear Magnetic Resonance of Inorganic Solids. Oxygen-17 Nuclear Magnetic Resonance Studies of Inorganic Oxides, Oxyanions, and Silicates
… have been obtained for a variety of oxides, oxyanions, carbonyls and for crystals and glasses in the system CaO-MgO-SiO(,2) using magic-angle sample spinning (MASS) and variable-angle sample spinning (VASS) techniques. The results (obtained by observation of the 1/2, - 1/2 central spin …
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Genetic relatedness of the family Rhodospirillaceae: Genome plasticity, chromosome heterogeneity, and chalcogenic oxyanion reductase activity in Rhodobacter sphaeroides
… at least fifteen other chalcogenic oxides and oxyanions has been demonstrated in the facultative photoheterotrophic bacterium, Rhodobacter (Rba.) sphaeroides. Detailed analyses have shown that HLR to at least one class of these oxyanions, the ""tellurite class"" (e.g., $\rm TeO\sb4\sp{2-},\ …
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Development of a sustainable water treatment technology for oxyanions using palladium-based catalysts: catalyst design, reaction mechanisms, and life cycle assessment
… when consumed even at low concentrations. These oxyanions are not removed via conventional drinking water treatment processes, and require specialized treatment. One emerging technology for destroying oxyanion water contaminants is catalytic reduction using supported Pd-based catalysts and an …
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Oxyanion reduction in a non-heme iron system
… of nitrite. Herein, the reduction of other oxyanions, the halogen and selenium oxyanions and chromate, to furnish the iron(III)-oxo complex was explored. In Chapter 2, the reduction of the halogen oxyanions to form the iron(III)-oxo complex and an iron(II)-halide complex is detailed. The …
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Application of phosphate and surfactant-modified zeolite for remediation/attenuation of trace elements in soil and coal fly ash
… (Pi) adsorption on ferric hydroxide. Both oxyanions showed similar adsorptions during single-ion adsorption experiments; however, As(V) was preferentially adsorbed during competitive adsorption experiments. Similarly, more As(V) was adsorbed when it was loaded in sequence in Pi-equilibrated …
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Selenium Stable Isotope Ratios in Wetlands: Insights Into Biogeochemical Cycling and How a Diffusive Barrier Affects the Measured Fractionation Factor
… isotope and concentration survey of dissolved Se oxyanions and reduced Se in a wetland/lake setting. Overall, no strong isotopic contrast was observed, with the mean values of Se oxyanions and major reduced reservoirs in plants and sediments of delta80/76SeSRM = 1.84‰ to 2.65‰. These …
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Development of sustainable Pd-based catalysts for removal of persistent contaminants from drinking water
… and a suite of persistent contaminants including oxyanions, N-nitrosoamines, and halogenated compounds are amenable to catalytic reduction. The primary goal of this study is to develop novel Pd-based catalysts with enhanced performance (i.e., activity, selectivity, and sustainability) to remove …
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Biotransformation and distribution of selenium in cultures of a salt-marsh yeast
… resulting from its ability to reduce selenium oxyanions to elemental selenium.
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Use of electrokinetic and reactive barriers to treat heavy metals-contaminated soils
… contaminated soil promoting the desorption of oxyanions under the influence of the alkalinity produced at the cathode and, in turn, enhancing their electromigration towards the anodic zone and the TRM RB; -- hydrogen ions generated at the anode during the EK process should provide the acidity …
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Evaluation of Leachate Chemistry from Coal Refuse Blended and Layered with Fly Ash
… and a suite of elements with a focus on the oxyanions of As, Cr, Mo, and Se. A sequential extraction procedure revealed a significant portion of the elements in the residual fraction for the refuse/spoil substrates and in metal-oxide bound fractions for the ashes prior to leaching, and a …
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The Determination of Trace Metals by High Performance Liquid Chromatography with Photometric Detection
… and the analysis of alloys. The separation of oxyanions is discussed with detection by a pyrocatechol violet ternary complex. The possibility of fluorescent metal detection with 8-hydroxyquinoline-5-sulphonic acid and photometric detection with a water soluble derivative of dithizone is shown.
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Small-scale heterogeneity in sediments : experimental and modelling investigations
… 2) an experimental study of analysis of oxyanions in sediment at high resolution that applied a newly developed preparation method for a combined AgI/FeOOH binding phase, to investigating processes occurring at a sulphidic microniche within a freshwater sediment; 3) analysis of the …
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Tellurium, antimony, and selenium isotopes as indicators of elemental mobility
… O2 levels at the Great Oxidation Event. For the oxyanions of the toxic metalloids, Sb and Te, one of the largest immobilizing processes is adsorption. Given the importance of this pathway, potential isotope effects induced by adsorption should be studied, as significant contribution from this …
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Trace element distributions in ridge flank sediments from the east Pacific Rise, and their use as proxies of past ocean conditions
… of the sediments under glacial conditions.<br/>Oxyanions coprecipitated with Fe and Mn (hydr)oxides from the hydrothermal plume (P, V, U) are<br/>partitioned during Fe-oxide alteration. V is preferentially incorporated into goethite and residual<br/>phases, locking the plume derived V within the …
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Hydroxy and amidinium containing acyclic and interlocked anion receptors
… containing [2]catenanes can associate with oxyanions with moderate affinity even in aqueous media, though it appears that these interactions are hindered by the lack of preorganisation within the system. Chapter Four reports the synthesis of two cationic hydroxy containing [2]rotaxanes and …
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