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Showing 1 to 20 of 81 for “"goethite"”.
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Competitive Adsorption of Arsenite and Silicic Acid on Goethite
… acid and arsenite alone and competitively on goethite over a broad pH range (3-11) at environmentally relevant concentrations was investigated utilizing pH adsorption data and zeta potential measurements. Both addition scenarios (Si before As(III) and As(III) before Si) were examined. The …
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Adsorption Properties of Roxarsone and Arsenate on Goethite and Kaolinite
… an organoarsenic poultry feed additive, to goethite and kaolinite in order to determine what role mineral surfaces play in controlling the mobility of roxarsone in watersheds where poultry litter is applied. Adsorption edge experiments for goethite and kaolinite showed a dependence on pH for …
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Interaction of aqueous U(VI) with goethite, montmorillonite, and UO2(s)
… models (SCMs) on adsorption of U(VI) onto goethite was analyzed for a broad range of input conditions. Individual models could fit the data for which they were parameterized, but they performed poorly when compared with experimental data covering a broader range of conditions. We developed …
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Interactions of arsenate, natural organic matter (NOM), and goethite (a-FEOOH)
Includes bibliographical references.
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The Influence of Oxyanions on the EDTA-Promoted Dissolution of Goethite
… phosphate on the EDTA-promoted dissolution of goethite and proposes a mechanism for the observed differences in dissolution rates over a pH range of 4 - 8. We propose that the surface complex formed by EDTA is the controlling factor for the observed dissolution rate, with mononuclear EDTA …
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Effect of adsorption of non-protolyzable anions on goethite (alpha-FeOOH) mobility
<P>THE PROCESSES OCCURRING AT THE SOLID-WATER INTERFACE ARE IMPORTANT CONTROLS ON THE MOBILITY OF MANY INORGANIC IONS IN THE ENVIRONMENT. ANION ADSORPTION ON IRON HYDROXIDE USUALLY DECREASES THE PARTICLE MOBILITY AND MAKES THE PARTICLE SURFACE LESS POSITIVE. HOWEVER, FOR SOME NON-PROTOLYZABLE …
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Desorption Kinetics of Lead from Goethite: Effect of Mixing and Sorption Period
… sorption period on the desorption of lead from goethite. Lead sorption was rapid and essentially complete in 1 h, with no change in the quantity of lead adsorbed over the 6 month sorption period. Desorption of lead was slower than the adsorption reaction and was best modeled by two first order …
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Multi-reactional kinetic modeling of phosphate sorption on goethite using artificial neural networks
… reactions on soil minerals, especially oxides. Goethite is one of the most important Fe oxides present in these soils, with sorption reactions occurring at the goethite-water interface defining P fate in such environment. As such, understanding the mechanisms controlling P sorption on these …
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The Influence of Residence Time and Organic Acids on the Desorption of Goethite
… acids on the desorption of Pb2+and Cd2+ from goethite. Adsorption experiments were conducted at pH 6.0. Lead adsorption was nearly completed after 4 hours, with very little additional sorption during a 20-week period. In contrast cadmium showed a continuous slight increase in the amount of …
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3D Printing of Specialty Devices for Geochemical Investigations: Real-Time Studies of Goethite and Schwertmannite Formation
… scattering (SAXS). Schwertmannite (pH 2.7) and goethite (6.2) are precipitated from solution using various setups and observed differences in growth rates are discussed. The data show the potential of 3D printing for enabling novel laboratory geochemical experiments.
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URANYL DEPOSITION IN UNCONFORMITY-RELATED DEPOSITS IN THE ATHABASCA BASIN: EVIDENCE FROM URANIUM SPECIATION IN HEMATITE AND GOETHITE
… U L3-edge XAS analyses show that uraniferous goethite associated with boltwoodite in late alteration assemblages of mineralized metapelites at the Eagle Point deposit is also dominated by the uranyl species, supporting its roles in late uranium remobilization.
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Degradation of groundwater contaminants by iron containing systems.
… study was to link changes in the mineralogy of goethite particles to changes in the reactivity of an Fe(II)-goethite system. The reactivity of Fe(II)-goethite and Fe(II)-goethite sand systems were quantified by monitoring the kinetics of trifluralin reduction. Changes in the goethite mineralogy …
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Role of Nanophase Oxides in Short-Term Atmospheric Corrosion of Structural Steels
… in particular chromium, in forming nanophase goethite was investigated. Crystallographic, magnetic and morphological properties of nanophase chromium substituted goethite have been characterized in order to understand the protective nature of chromium-substituted goethite in a naturally …
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Surface complexation modeling of Pb(II), Cd(II) and Se(IV) onto iron hydroxides in single and bisolute systems
… 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 characterize the mineral …
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Manganese mineralization hosted by the Rocky Gap Sandstone in Bland County, Virginia
… deeply as 4 km and heated to 150°C. Romanechite, goethite, and pyrolusite are the three most important oxides, and can coexist at 25°C and 1 bar. In polished section romanechite has three textures: (1) microcrystaline patches, (2) fibers. Pyrolusite occurs as occurs in three textures : botryoidal …
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Geochemical Conditions Affecting Uranium(VI) Fate And Transport In Soil And Groundwater In The Presence Of Phosphate
… the interactions among phosphate, U(VI), and goethite: alpha-FeOOH) were investigated in a year-long batch experimental study. Dissolved U(VI) and phosphate concentrations were interpreted within a reaction-based modeling framework. U(VI) uptake mechanism varied with the aqueous composition. …
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Degradation Of Selected Organic Agrochemicals In Artificial Soil Slurry Systems By Anodic Fenton Treatment
… humic acid, kaolin or montmorillonite clay, and goethite, on the degradation of different groups of agrochemicals, including carbaryl, mecoprop, paraquat, 4.6-odinitrocresol, p-nitrophenol and dinoseb, were studied. The results indicate that humic acid content is the key factor that slows down …
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Mineral-Microbe Interactions Probed in Force, Energy, and Distance Nanospace
… the case of Escherichia coli interactions with goethite, graphite, and muscovite, attractive and repulsive forces were detected at ranges up to 400 nanometers, the magnitude and sign depending on the ionic strength of the intervening solution and the mineral surface charge and hydrophobicity. …
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Boron chemistry in selected Virginia soils and hydroxy aluminum and iron systems
… forms. Boron adsorption on both gibbsite and goethite was pH and temperature dependent. At pH 6.5, boric acid was major species in the system and B was absorbed by the negatively charged surface of gibbsite and the positively charged surface of goethite. At pH 10, borate was primarily species …
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Trace Element Cycling during Iron(II)-activated Recrystallization of Iron(III) Oxide Minerals
… controls on net trace element release from goethite and hematite, 3) explore surface passivation and trace element release inhibition during Fe(II)-activated recrystallization of iron oxides containing insoluble elements, and 4) determine the fate of redox-sensitive metals that are …
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