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Showing 1 to 20 of 43 for “"ferrihydrite"”.
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The Role of Iron in Nontronite and Ferrihydrite
… in determining the properties of nontronite and ferrihydrite was studied to better understand these minerals.
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Effects of phytic acid sorption on iron polymerization and at the ferrihydrite-water interface
… this study, sorption behavior of phytic acid in ferrihydrite was examined using experimental geochemistry, solution 31P nuclear magnetic resonance spectroscopy, X-ray diffraction and scanning electron microscopy. The results indicated inner-sphere surface complexation via P1,3 and P2 functional …
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Insights on the reactivity of environmental iron-containing nanoparticles.
… redox reactions and adsorption of trace species. Ferrihydrite (Fe5HO8*4H2O) is a metastable iron oxide that forms particles in the 3-10 nm size range and is believed to be a major player in the environment. The reactivity of ferrihydrite is influenced by the available surface area which is known …
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Interactions of molybdenum and vanadium with iron nanoparticles
… affects many different processes. Poorly ordered ferrihydrite nanoparticles characterised for their particle size (3-5nm), crystallinity, surface area (~200m2g-1) and surface charge (point of zero charge = 7.96) helped to understand better their adsorption and co-precipitation interactions …
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Surface complexation modeling of Pb(II), Cd(II) and Se(IV) onto iron hydroxides in single and bisolute systems
… (TLM) parameters for two iron (hydr)oxides, ferrihydrite (HFO) and goethite (α-FeOOH). To this end, spectroscopic data were used to guide the selection of surface complexation model reactions, and to the extent possible, theoretically based parameter estimation techniques were used to …
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Iron reduction mediated increases in carbon oxidation and phosphorus precipitation in on-site wastewater systems
… additional Fe2+ was present. Ferric citrate, ferrihydrite and ferrihydrite+AQDS completely removed (>95.5% or higher) of phosphate in the original wastewater sample. Ferric citrate and ferrihydrite+AQDS performed better (>97.5 or higher) when an extreme phosphate loading condition was …
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Influence of protozoan grazing on the marine geochemistry of particle reactive trace metals
… phases, specifically colloidal iron oxide (ferrihydrite). Several independent techniques were employed, including size fractionation ors9Fe-labeled colloids, competitive ligand exchange, and iron-limited diatoms as "probes" for bioavailable Fe. Experimental evidence strongly suggests that …
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Reactivity of Iron-Bearing Minerals Under Carbon Sequestration Conditions
… of H2S or SO2 contaminants with CO2. Both ferrihydrite and hematite nanoparticles were exposed to an aqueous Na2S solution in the presence of supercritical CO2 (scCO2) and were analyzed in situ by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). In situ …
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Decomposition of hydrogen peroxide and organic compounds in the presence of iron and iron oxides
… at pH 4 containing either dissolved Fe(III) or ferrihydrite. Combined with the results from experiments using a radical chain terminator, we concluded that a solution chain reaction was important only in the Fe(III) system. In the ferrihydrite system the amount of dissolved Fe was insufficient …
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Arsenic Adsorption on Iron Oxides in the Presence of Soluble Organic Carbon and the Influence of Arsenic on Radish and Lettuce Development
… 4: Adsorption of Arsenate and Arsenite on Ferrihydrite in the Presence and Absence of Dissolved Organic Carbon (DOC) The adsorption of As (V) and As (III) on synthetic 2-line ferrihydrite in the presence and absence of a peat humic acid (Hap), Suwannee River Fulvic Acid (FA) or citric acid …
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The mobility of metals in acid mine drainage from abandoned coal mines
… with minor amounts of goethite, lepidocrocite, ferrihydrite and gypsum, with ferrihydrite being the major component of only one precipitate sample. The presence of algae at one of the sampling sites appeared to act as a template for the precipitation of ferrihydrite in a low pH and high acidity …
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Cycling of Iron and Manganese (Oxyhydr)oxides in the Presence of Organic Matter
… We find that the poorly crystalline mineral ferrihydrite delays the onset of methanogenesis relative to controls while more well crystalline hematite and goethite do not. We also find that only ferrihydrite-amended microbial communities differ considerably from controls based on 16S-rRNA …
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Arsenic mobilization through bioreduction of iron oxide nanoparticles
… experiments containing an arsenic-bearing ferrihydrite and an Fe(III)-reducing microorganism, Geobacter metallireducens. Results show that arsenic mobility is strongly controlled by microbially-mediated disaggregation of arsenic-bearing iron nanoparticles. The most likely controlling …
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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
… redox status of the sediments. Amorphous ferrihydrite phases delivered to the sediment<br/>have undergone significant alteration to more stable crystalline forms. Under glacial conditions, the<br/>transformation of ferrihydrite appears to be impeded, which is inferred to be a function of a …
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The reactivity of ferric (hydr)oxides towards dissolved sulphide
… 3. Batch experiments with dissolved sulphide and ferrihydrite, lepidocrocite, and goethite were performed under well-defined conditions at pH 7 and at room temperature in a glove box with a special emphasis on the characterization of nanocrystalline products forming at different time steps over a …
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Diffusive gradients in thin films (DGT) as a technique to predict nutrient availability to plants
… in these environments. The MBL consisted of ferrihydrite and Chelex - 100 cation exchange resin combined together in a binding gel. Results from the MBL were comparable to experiments performed using individual Chelex gels and ferrihydrite gels that have been shown to work successfully for …
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Formation and transformation kinetics of iron oxy-hydroxides and effects of adsorbed oxyanions
Iron (Fe) oxy-hydroxides such as ferrihydrite (Fh) are ubiquitous in surface environments. Because of their high surface area and high reactive surface, they can immobilize environmental contaminants and nutrients (e.g., oxyanions) through adsorption. Ferrihydrite is metastable and eventually …
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Chemical bath deposition and electrodeposition of epitaxial semiconductor materials for application in photovoltaic devices
… transformation of electrodeposited magnetite and ferrihydrite into hematite"--Abstract, page iv.
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The biogeochemistry of marine particulate trace metals
… We demonstrate solubilization of minerals ferrihydrite and fayalite via transfer of isotopic label into suspended particles.
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Spectral Reflectance as an Indicator of Water Quality in Streams Impacted by Mine Drainage
… and goethite while near neutral watersformed ferrihydrite. The minerals comprising the sediments occurring at each pH mode are spectrally separable. Color indices and spectral angle mapping of the sediments correlated with stream water pH. Continuum removal analysis of mineral VNIRreflectance …
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